Carrier PC 111 User Manual

48FK,JK034-104

48FM078-104

50FK,FY,JK,JY034-104

50FM,FS078-104

Variable-Air Volume Rooftop Units

Controls Operation,

and Troubleshooting

CONTENTS

Page

Control From Remote Building Management

SAFETY CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . 2

System (BMS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13

Rooftop Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

VAV Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Processor Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

• P1 — SUPPLY-AIR SET POINT

• OCCUPIED/UNOCCUPIED

• NIGHT SETBACK CONTROL

• UNIT SUPPLY AIR SET POINT ADJUSTMENT

• DEMAND UNIT (1-STAGE OR 2-STAGE)

• SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT

• EXTERNAL ALARM SIGNAL

• P2 — ECONOMIZER POSITION

• P3 — RESET LIMIT

• REMOTE ECONOMIZER CONTROL

Smoke Control Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . 21

• FIRE SHUTDOWN MODE

• P4 — DEMAND LIMIT

• P5 — ECONOMIZER MINIMUM POSITION

• P6 — WARM-UP SET POINT

• PRESSURIZATION MODE

• P7 — SASP RESET TEMPERATURE

• EVACUATION MODE

• PROCESSOR BOARD OUTPUTS

• CONFIGURATION HEADER AND DIP SWITCH

ASSEMBLY

Relay Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Display Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

• T1 — SUPPLY-AIR TEMPERATURE THERMISTOR

• T2 — RETURN-AIR TEMPERATURE THERMISTOR

• T3 — SATURATED CONDENSING TEMPERATURE,

CIRCUIT 1

• SMOKE PURGE MODE

• INSTALLATION

• CONFIGURATION

• OPERATING SEQUENCE

Air Pressure Tubing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

• INLET GUIDE VANES

• SUPPLY FAN VARIABLE FREQUENCY DRIVE

• MODULATING POWER EXHAUST

START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25-31

Initial Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Configuration Header . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

DIP Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Adjusting Set Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Potentiometers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Supply Fan Control with IGV Option . . . . . . . . . . . . 28

Supply Fan Control with VFD Option . . . . . . . . . . . . 28

Modulating Power Exhaust Option or

Accessory) (48FK,JK and 50FK,JK Units) . . . . . 30

High Capacity Power Exhaust

(48FM and 50FM,FS Units) . . . . . . . . . . . . . . . . . . . . 30

START UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31-34

Quick Test Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

• T4 — SATURATED CONDENSING TEMPERATURE,

CIRCUIT 2

• T10 — RESET TEMPERATURE

Compressor Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . 7

• CONTROL RELAY (CR)

Accessory Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

• P3 — RESET LIMIT

• P5 — ECONOMIZER MINIMUM POSITION

• P6 — MORNING WARM-UP TEMPERATURE

Single-Step Demand Unit. . . . . . . . . . . . . . . . . . . . . . . . . 7

Demand Limit Control Module (DLCM) . . . . . . . . . . . 7

Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

• ENTHALPY CONTROL

• DIFFERENTIAL ENTHALPY

OPERATING INFORMATION. . . . . . . . . . . . . . . . . . 34-44

Digital Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

• CODES 0 THROUGH 8, CAPACITY STEPS

• CODES 20 THROUGH 30 AND 88, OPERATIONAL

STATUS

Supply Fan Variable Frequency Drive (VFD). . . . . 12

High Capacity Modulating Power

Exhaust Variable Frequency Drive . . . . . . . . . . . . 12

Temperature Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

CONTROLS INSTALLATION. . . . . . . . . . . . . . . . . . 13-25

Control Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

• NIGHT SETBACK THERMOSTAT

• SPACE TEMPERATURE RESET ACCESSORY

(50DJ900021)

• CODES 51 THROUGH 87, DIAGNOSTIC

INFORMATION

Operating Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

• SIZE 034, 038 AND 048-088 UNITS

• SIZE 044 UNITS

• SIZE 104 UNITS

Space Temperature Reset . . . . . . . . . . . . . . . . . . . . . . 13

• INSTALLATION

Head Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Supply Fan Control with IGV . . . . . . . . . . . . . . . . . . . . 38

Supply Fan Control with VFD. . . . . . . . . . . . . . . . . . . . 38

Modulating Power Exhaust (48FK,JK and

50FK,JK Units Option or Accessory). . . . . . . . . . 38

High Capacity Modulating Power Exhaust

(48FM and 50FM,FS Units) . . . . . . . . . . . . . . . . . . . . 38

Unit Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

• CONFIGURATION

• OPERATING SEQUENCE

Demand Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

• SINGLE-STEP DEMAND LIMIT

• TWO-STEP DEMAND LIMIT

• INSTALLATION

• CONFIGURATION

• OPERATING SEQUENCE

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

PC 111 Catalog No. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg 1 3-00 Replaces: 48/50F,J-1T

Book 1

Tab 1a 1b

The VAV control system monitors and controls the follow-

ing functions of the rooftop unit:

Several status switches are also monitored. These switches

are connected to the processor at pin terminal connector J2. See

Fig. 3 and Table 2.

In addition to the unit status switch inputs, the processor

board also accepts inputs from several potentiometers. These

potentiometers control various operational characteristics of

the system. Inputs are received by the processor through pin

terminal connector J3. See Fig. 4.

•

supply-air temperature (unit capacity)

morning warm-up or electric heat (if equipped)

head pressure control, fan cycling

economizer position

diagnostic display

unit check-out (quick test)

supply air temperature reset (if equipped)

demand limiting (if equipped)

Table 1 — Pin Terminal Connector J1

Thermistor Inputs

Processor Board — The processor board, shown in

Fig. 1, contains the logic and the necessary hardware to drive

the outputs and the display board. The processor board is en-

closed by a sheet metal cover and a heater. The heater is con-

trolled by a thermostat to keep the processor temperature above

32 F (0° C). All electrical connections are made to the proces-

sor board through wire and ribbon cables.

CONNECTOR J1

TERMINAL NO.

TEMPERATURE

INPUT

Reset Temperature*

Saturated Condensing

Temp., Circuit 2

Saturated Condensing

Temp., Circuit 1

UNIT SIZE

034-104

1,2

T10

14,15

16,17

Several temperature inputs are connected to the processor.

There are either 4 or 5 thermistors (depending on the field-

installed accessories) which input temperature data into the

processor through pin terminal connector J1. See Table 1 and

Fig. 2.

18,19

20,21

Return-Air Temperature

Supply-AirTemperature

LEGEND

T — Thermistor

*If equipped with accessory temperature reset package.

NOTE: Terminal numbers 3-13 are not used on these units.

LEGEND

DIP

EPPOM — Erasable, Programmable Read-Only Memory

EXV — Electronic Expansion Valve

— Dual In-Line Package

*EPROM HT204485-1-XX where “XX” is the current revision

number.

NOTE: Processor Board is positioned in unit with J3 and J10

connections at the bottom.

Do not remove label covering EPROM. Removal causes pro-

gram to be erased.

Fig. 1 — Processor Board

LEGEND

—

Control Relay

Enthalpy Control

LEGEND

LPS — Low-Pressure Switch

—

Thermistor

Field Wiring

Accessory

Fig. 3 — Pin Terminal Connector J2

Status Switch Inputs

Fig. 2 — Pin Terminal Connector J1

Thermistor Inputs

Table 2 — Pin Terminal Connector J2

Status Switch Inputs

CONNECTOR J2

TERMINAL NO.

UNIT SIZE

034-104

STATUS SWITCH

Oil Pressure,

Circuit 2

Oil Pressure,

Circuit 1

Loss of Charge,

Circuit 2

1,2

Jumpered

LPS2

3,4

7,8

Loss of Charge,

Circuit 1

9,10

LPS1

Economizer

Changeover

Compressor Fault

Signal

Compressor Fault

Signal

13,14

15,20

15,24

LEGEND

CR2

CR1

LEGEND

— Input

Factory Wiring

Field Wiring

Accessory

CR — Control Relay

— Potentiometer

— Return

EC — Enthalpy Control

RNT

LPS — Low-Pressure Switch

— Switch

NOTE: Terminal numbers 5, 6, 11, 12, 16-19, and 21-23 are not used

on these units.

Fig. 4 — Pin Terminal Connector J3

Potentiometer Inputs

All of the potentiometers must be set before the unit is start-

ed in order for the unit to function properly. See Start Up, Po-

tentiometers section on page 27 for information on establishing

set points. Each of the potentiometers has a valid range that is

used by the control. The valid range is defined as the potenti-

ometer’s resistance value that the control will not consider to

be in error. This is usually between 10% and 90% of the poten-

tiometer’s total resistance. The control has been programmed

to accept an operational range for the potentiometer, which

may not be the same as the valid range.

CONFIGURATION HEADER AND DIP SWITCH ASSEM-

BLY — The processor board is programmed to control a vari-

ety of air conditioning units. To tailor the processor to the par-

ticular unit being controlled, 2 devices are used. One is the

configuration header, and the other is the DIP switch assembly.

The configuration header (part no. 30GB660001) is a series

of 8 small wires that are broken or unbroken in a pattern to in-

dicate several unique characteristics of the unit. The configura-

tion header is factory set and should not be changed. Changing

the factory setting may cause the unit to malfunction.

The DIP switches configure the unit for several field-in-

stalled options, as well as for several other options that may be

unique to the unit. The DIP switches are located under a plastic

enclosure which must be removed for access. The switches can

be field adjusted, but must be adjusted only when the unit con-

trol circuit breaker is off.

The potentiometer locations and functions are as follows:

P1 — SUPPLY-AIR SET POINT — This potentiometer is

located on the display board. The supply-air set point is the

cooling mode control temperature which the VAV control sys-

tem will attempt to maintain at Thermistor T1 by control of

economizer position and/or cycling unloaders and compres-

sors.

P2 — ECONOMIZER POSITION — Economizer feedback

potentiometer is located on the economizer motor. The micro-

processor is programmed to indicate an alarm if the travel dur-

ing initialization is less than 10% of the total potentiometer’s

resistance. An alarm condition will also be signaled if the

potentiometer fails during operation, indicating that the

damper blades are stuck. If either situation occurs, the proces-

sor will try to drive the economizer dampers closed.

P3 — RESET LIMIT — This potentiometer is located on the

accessory board (provided standard from the factory) in the

unit main control box and establishes the maximum amount of

reset that can be applied to the supply-air set point (P1). Reset

is limited by the P1 default of 70 F. This potentiometer is used

only when accessory, field-installed temperature reset is used.

If temperature reset is used, DIP (dual, in-line package) switch

2 must be in the ON position.

P4 — DEMAND LIMIT — This potentiometer is located near

TRAN4 in the unit control box. The demand limit potentiome-

ter is used only if accessory, field-installed demand limit is

used, and if DIP switch 5 is in the ON position. For single-step

demand limit, a field-installed 5 to 20 Kohm potentiometer and

switch must be used.

P5 — ECONOMIZER MINIMUM POSITION — This

potentiometer is on the accessory board (provided standard

from the factory) located in the unit main control box. This

potentiometer specifies the minimum opening position for the

optional economizer. If a fault condition is detected by the pro-

cessor, an alarm condition will be signaled and the economizer

dampers will close.

P6 — WARM-UP SET POINT — This potentiometer is on

the accessory board (provided standard from the factory)

located in the unit main control box. This potentiometer estab-

lishes the set point temperature for the Morning Warm-Up

function. When the temperature is reached, Morning Warm-Up

is terminated and VAV operation begins. DIP switch 4 must be

in the ON position if morning warm-up heat is to be used.

Relay Board — The relay board is used to control 24-v

and 115-v loads. See Fig. 5. The relay board is connected to the

processor board by a ribbon cable at pin J9. Electrical connec-

tions to the relay board are made through pins J5 (115 v) and J6

(24 v). The relay board has eight 24-v relays and five 115-v re-

lays. See Table 3.

Display Board — The display board is located in the

main unit control box and is connected to the J10 port of the

processor board through a ribbon cable. The display board con-

tains the supply-air set point potentiometer P1; a 2-digit, LED

display; and the display button (see Fig. 6). The LED display is

used to convey the operating information and operational error

codes.

Thermistors — The processor uses up to 5 thermistors to

sense the temperatures at various points in the system. See Ta-

ble 1 and Fig. 7-14. All the thermistors have identical tempera-

ture versus resistance and voltage drop characteristics, and are

monitored by the processor for a short or open circuit. The val-

id range for a thermistor is 362,640 to 219 ohms. Thermistor

details and locations are as follows:

T1 — SUPPLY-AIR TEMPERATURE THERMISTOR —

This thermistor is located in the unit supply fan discharge. It

provides information for the processor to stage the number of

capacity steps required to maintain a desired supply-air tem-

perature.

T2 — RETURN-AIR TEMPERATURE THERMISTOR —

This thermistor is located in the mixed-air portion of the unit

cabinet. The thermistor’s primary function is to provide morn-

ing warm-up information. This sensor will also provide differ-

ential information for the processor during cooling operation

(such as the rate of change for a capacity step).

T3 — SATURATED CONDENSING TEMPERATURE,

CIRCUIT 1 — This thermistor is located on the condenser coil

return bend. See Fig. 13 and 14. It controls the staging of the

unit condenser fans based on the condensing temperature of

the refrigerant at the designated position on the condenser coil.

P7 — SASP (SUPPLY AIR SET POINT) RESET TEMPER-

ATURE — This 10 Kohm potentiometer is used only if the

accessory, field-installed temperature reset package is installed.

This potentiometer determines the temperature at which reset

will begin. It is located on the accessory temperature reset

board. DIP switch 2 must be in the ON position to enable

SASP reset.

PROCESSOR BOARD OUTPUTS — The processor board

also controls outputs through the relay board. The relay board

plugs into the processor board using a ribbon cable.

T4 — SATURATED CONDENSING TEMPERATURE,

CIRCUIT 2 — This thermistor is located on the condenser coil

return bend. See Fig. 13 and 14. It controls the staging of the

unit condenser fans based on the condensing temperature of

the refrigerant at the designated position on the condenser coil.

T10 — RESET TEMPERATURE — This thermistor is used

only if the accessory temperature reset package is used. It pro-

vides occupied space temperature information to the processor,

which determines whether or not reset is required. The ther-

mistor is remotely mounted outside the unit in the conditioned

space.

In addition, the processor board controls the display board. The

display board is connected to the processor board by a ribbon

cable, and has an LED (light-emitting diode) display showing

the status of the unit and diagnostic information.

Table 3 — Output Pin and Terminal Assignments

OUTPUT PIN-

TERMINAL

NAME

RATING

DEVICE

CR1

Stage 1

J6-1

J6-2

Compressor Relay (K1)*

Stage 2

U2**

Compressor Relay (K2)*

Stage 3

J6-3

J6-4

J6-5

Not Used

CR2

Compressor Relay (K3)*

Compressor Relay (K4)†

Stage 5

Compressor Relay (K5)†

24 vac

Stage 6

Compressor Relay (K6)†

J6-6

Not Used

J6-7

J6-8

J5-1

J5-2

Economizer Open Relay (K7)

Economizer Close Relay (K8)

Supply Fan Relay (K9)

EOR

ECR

IFC

Morning Warm-Up Relay (K10)

HIR

Stage 1 Condenser

Fan Relay (K11)

J5-3

OFC2/OFC3††

115 vac

Stage 2 Condenser

Fan Relay (K12)

External Alarm Relay (K13)

J5-4

J5-5

OFC4||

ALM

LEGEND

*Circuit 1.

†Circuit 2.

ALM — Alarm

**U2 is not used on 044 units.

CR — Control Relay

††OFC2 on 034-048 units; OFC3 on 054-104 units.

ECR — Economizer Close Relay

EOR — Economizer Open Relay

HIR — Heat Interlock Relay

||Used on 054-104 units only.

IFC — Indoor (Evaporator) Fan Contactor

OFC — Outdoor (Condenser) Fan Contactor

— Unloader

LEGEND

CR — Control Relay

— Terminal Pin Connectors

— Relay

Fig. 5 — Relay Board

P1 SUPPLY AIR

SET POINT

POTENTIMETER

TWO-DIGIT

DISPLAY

BUTTON

P3 — RESET LIMIT — The processor board is programmed

for occupied space temperature reset. In order for reset to

work, the accessory temperature reset board must be used.

Potentiometer P3 is the maximum set point temperature to

which the supply air can be reset.

P5 — ECONOMIZER MINIMUM POSITION — This

potentiometer controls the set point for the minimum position

of the economizer.

P6 — MORNING WARM-UP TEMPERATURE — This

potentiometer controls the morning warm-up temperature set

point.

Single-Step Demand Limit — The single step de-

mand limit provides a means to limit the capacity of the VAV

unit using an external switch. Single step demand limit will

limit the compressor displacement based on the ratio of the

wiper arm to the full scale resistance. The exact percentage of

capacity reduction differs depending on the number of capacity

steps.

A 3-wire, 5 to 20 Kohm, field-supplied potentiometer (P4)

is required for this option. The potentiometer should be wired

to the processor J3 connections. In order to control the demand

limit, the wiper arm of the potentiometer should be switched

open and closed based on the demand limit requirement. The

control switch is also field-supplied and installed.

If the wiper arm wire is open, all capacity stages can be

used. When the wiper arm wire is closed, the capacity is re-

duced by the amount set on potentiometer P4.

Fig. 6 — Display/Set Point Board

Compressor Operation

CONTROL RELAY (CR) — This relay provides information

to the processor about compressor operation (one control relay

per compressor). The relay controls and protects the compres-

sor and also controls the crankcase heater.

Demand Limit Control Module (DLCM) — The

DLCM provides a 2-step demand limit control using an exter-

nal switch. The first step is between 50% and 100% of the

maximum compressor displacement. See Fig. 16. The second

step is between 0% and 49% of the maximum compressor dis-

placement. The exact percentage differs depending on the

number of capacity steps.

Two adjustable potentiometers are used to set the 2 demand

limit points. Potentiometer P1 is used to set a demand limit

between 50% and 100% of the unit capacity. Potentiometer P2

is used to set a demand limit between 0% and 49% of unit

capacity.

If no power is supplied to the demand limit control module,

all capacity stages can be used. When power is supplied to ter-

minal IN1 only, the first step of the demand limit control is en-

ergized and the capacity is reduced by the amount set on poten-

tiometer P1. When power is supplied to terminal IN2 only, or

to both IN1 and IN2, the capacity is reduced by the amount set

on potentiometer P2.

A control signal to check the safety statuses and to start the

compressor is sent from the relay board. This signal travels

through all of the safeties: the high-pressure switch, and the in-

ternal protector (where used) and on to the control relay coil.

Once the control relay coil has been energized, the control re-

lay completes a feedback circuit for the processor, informs the

processor of the status of the compressor safeties, energizes the

compressor contactor coil, and deenergizes the crankcase heat-

ers. A fault will be detected by the processor if the control relay

opens during operation or startup. The processor will lock the

compressor or the circuit off by deenergizing the appropriate

relay(s) on the relay board and energizing an alarm signal.

Accessory Board — The accessory board is standard

(factory supplied) in the VAV rooftop units. See Fig. 15. This

board is located in the control box of each unit. Each board has

a prewired connector supplied with it to connect directly to the

processor board. It has 3 potentiometers: P3, P5, and P6.

GAS SECTION

(48FK,JK ONLY)

HORIZONTAL SUPPLY SECTION

(50FY,JY ONLY) AND EXTENDED

PLENUM SECTION (50FKX,FKY,JKX,JKY)

Fig. 7 — Thermistor T1 Location, 48FK,JK, 50FY,JY and 50FKX,FKY,JKX,JKY 034-048 Units

FAN DISCHARGE/ELECTRIC HEAT SECTION

Fig. 8 — Thermistor T1 Location, 50FK,JK034-048 Units

HORIZONTAL SUPPLY SECTION (50FS,FY,JY)

AND EXTENDED

PLENUM SECTION (50FKX,FKY,FMX,FMY,JKX,JKY)

GAS SECTION

(48FK,FM,JK)

Fig. 9 — Thermistor T1 Location, 48FK,FM,JK, 50JY and

50JKX,JKY 054-074 Units and 50FKX,FKY,FMX,FMY and 50FS,FY054-104 Units

FAN DISCHARGE/ELECTRIC HEAT SECTION

Fig. 10 — Thermistor T1 Location, 50FK,JK054-074 Units

BAG

FILTERS

STANDARD

FILTERS

Fig. 11 — Thermistor T2 Location, Size 034-048 Units

Fig. 13 — Thermistor T3 and T4 Locations,

Size 034-048 Units

ENTHALPY CONTROL

48FK,JK and 50FK,FY,JK,JY Units — Outside air enthalpy

control is standard with the factory-installed economizer op-

tion. Enthalpy is sensed by a controller located behind the end

outside air hood. The control can be accessed by removing the

upper hood filter. See Fig. 17.

48FM and 50FM,FS Units — The control is located on the

metal upright between the two economizer hoods, on the right

hand side of the unit, and can be accessed by removing the fil-

ter on either economizer hood.

DIFFERENTIAL ENTHALPY — Added efficiencies in econ-

omizer control can be gained by installing a differential en-

thalpy sensor in the return air duct. When differential enthalpy

control is installed, the economizer control will use the air

stream with lower enthalpy (outside air or return air) to provide

for lower compressor operating costs during integrated econo-

mizer cycle operation. The differential enthalpy sensor is

installed in the return-air duct.

BAG FILTERS

(054-074 Only)

STANDARD FILTERS AND

PLEATED FILTERS

Fig. 12 — Thermistor T2 Location, Size 034-048 Units

Economizer — Economizer control is used to control the

outside and return air dampers of the unit, to satisfy space cool-

ing demand using all outside air (when permitted), and to satis-

fy cooling in conjunction with compressor operation (when

conditions permit). During Occupied periods without cooling

demand, the outside-air dampers will be at the user-configured

Minimum Damper Position (at P5 on accessory board). During

Unoccupied periods, the outside-air dampers will be closed.

The economizer is a standard feature on 48FM and

50FM,FS units and is available as a factory-installed option on

48FK,JK and 50FK,FY,JK,JY units.

The user can install an accessory differential enthalpy sen-

sor to enhance economizer control. Refer to the installation

section for field wiring of the sensor.

054 UNITS

064, 074, 078 UNITS

088, 104 UNITS

Fig. 14 — Thermistor T3 and T4 Locations, Size 054-104 Units

The unit is supplied with a pressure transducer capable of

measuring from 0.0 to 5.0 in. wg. The pressure transducer will

send a 4 to 20 mA signal to the VFD to modulate the speed of

the indoor fan motor to precisely control the fan to the desired

static pressure set point. The VFD is factory set at 2.5 in. wg

duct static pressure. Refer to the Operating Sequence section

for more information on the VFD.

The VFD has been programmed and wired at the factory for

this application. No further adjustments (except for Duct Static

Pressure Set Point) should be necessary at start-up. Factory

jumper wire configurations are shown in the Supply Fan Con-

trol with VFD Option section on page 28.

A separate service manual for the factory-installed VFD is

supplied with each unit. Refer to the VFD manual for more in-

formation on the VFD controls.

LEGEND

High Capacity Modulating Power Exhaust

Variable Frequency Drive (48FM and 50FM,FS

Units Only) — The power exhaust VFD (PE VFD) is used

to modulate the power exhaust fan motor no. 1 and stage the

power exhaust fan motor no. 2 in order to maintain building

static pressure. The PE VFD is located at the return air end of

the unit of the opposite side from the auxiliary control box and

can be accessed by opening the access door.

The unit is supplied with a pressure transducer capable of

measuring from –0.5 to +0.5 in. wg. The pressure transducer

will send a 4 to 20 mA signal to the PE VFD to modulate the

speed of the power exhaust motor no. 1 and also stage on/off

the power exhaust motor no. 2 to precisely maintain the desired

building pressure set point. The PE VFD is factory set at

0 in. wg. Refer to Operating Sequence section for more infor-

mation on the PE VFD.

ECON — Economizer

MIN

— Minimum

— Potentiometer

VAV — Variable-Air

Volume

Fig. 15 — Accessory Relay Board

(Standard; Factory Supplied)

The PE VFD has been programmed and wired at the factory

for this application. No further adjustments (except for Build-

ing Pressure Set Point) should be necessary at start-up. Factory

jumper wire configurations are shown in the Power Exhaust

Variable Frequency Drive section in the Troubleshooting sec-

tion on page 55.

LEGEND

— Integrated Circuit

— Input

— Potentiometer

RTN — Return

Fig. 16 — Two-Step Demand Limit Module

Fig. 18 — Variable Frequency Drive,

Sizes 034-048 and 078-104

Fig. 17 — Enthalpy Sensor Location

(48FK,JK and 50FK,FY,JK,JY Units Only)

Supply Fan Variable Frequency Drive

(VFD) — The optional VFD is used to modulate supply fan

airflow to maintain duct static pressure on VAV applications.

The VFD is located in the supply fan section (see Fig. 18 and

19), and can be accessed by opening the fan section access

door.

Fig. 19 — Variable Frequency Drive, Sizes 054-074

A separate service manual for the factory installed PE VFD

is supplied with each unit. Refer to PE VFD manual for more

information on the PE VFD.

control box. When unit goes into Heating mode, interlock relay

is energized providing switch closure or opening (depending

on how field power source is set up) to open the room termi-

nals. Field connections for interlock relays are terminals 3 and

4 (for normally open contacts) and terminals 3 and 7 (for nor-

mally closed contacts) on terminal block 3 (sizes 034-048) or

terminal block 4 (sizes 054-104). See Fig. 24. Note that a field-

supplied power source is required.

There are no required 115-volt field wiring connections,

therefore no provisions have been made in the unit for running

115-volt wiring. If any of the field-installed options requiring

115-volt connections are desired, the unit must be modified in

the field for 115-volt wiring.

NIGHT SETBACK THERMOSTAT — Wire field-supplied

thermostat (suitable for 24-v circuit) between terminals 1 and 2

on terminal block 3 (sizes 034-048) or terminal block 4

(sizes 054-104). This thermostat is used to bypass the time-

clock occupied/unoccupied switch and is used to operate unit

during unoccupied times at more economical temperatures.

(See Fig. 23.)

SPACE TEMPERATURE RESET ACCESSORY (50DJ900021)

— Consists of a thermistor (T10) and a reset board with a potenti-

ometer (P7) that is used to set space temperature at which reset

starts. Mount reset board in unit control box or other convenient

place. Wire thermistor in series with P7 and connect to terminals

12 and 15 on terminal block 3 (sizes 034-048) or terminal block 4

(sizes 054-104) in unit control box. If there is a long run to condi-

tioned space, it is necessary to splice additional wire to thermistor.

The reset board has 2 pressure connectors for field wiring. (See

Fig. 25.)

Temperature Reset — Accessory temperature reset al-

lows the unit to automatically adjust (‘‘reset’’) the supply-air

temperature set point to a higher value once most of the space

cooling load has been met. When the space conditions are sat-

isfied, the VAV terminals will close to the minimum position.

All VAV units will sense the decrease in actual supply-air tem-

perature and the unit controls respond by reducing capacity

stages to maintain user-established supply-air set point temper-

ature. When VAV units are also equipped with optional supply

duct pressure controls (either inlet guide vanes [IGV] or vari-

able frequency drive package), the unit also senses an increase

in duct static pressure and responds by closing IGV dampers or

slowing fan wheel speed to maintain user-configured set points

for supply duct pressure. Allowing the supply-air temperature

to be reset to a higher value maintains air circulation in the

space without costly overcooling.

The accessory package is required for temperature reset.

The accessory includes:

•

thermistor T10, to monitor space temperature

reset temperature potentiometer P7, to establish start

temperature for reset operation

reset limit potentiometer P3, to establish maximum level

of modified supply-air temperature

•

More than one space sensor may be used if an average

space temperature is desired for initiating temperature reset.

Refer to installation section for sensor part number and wiring

schematic.

Space Temperature Reset

INSTALLATION — Install the accessory temperature reset

package in accordance with instructions provided with the

accessory kit.

Mount the reset board in the unit control box (or other suit-

able location) per instructions.

Locate the thermistor T10 in a suitable location in the occu-

pied space per instructions.

Temperature reset will start when space temperature (at

T10) drops to the set point at P7. When Temperature Reset

is active, the LED (light-emitting diode) display will show

code 21 . Automatic adjustment of supply-air temperature set

point will end when modified SASP equals reset limit set point

at P3. (See formula for automatic modification of SASP in

Controls Installation, Space Temperature Reset section on this

page.)

Wire T10 to the reset board and to the unit control terminal

block per Fig. 25. Wire the other terminal on the reset board to

the unit control terminal block per Fig. 25.

If multiple sensors are required to average the space temper-

ature, see Fig. 26. Use only Carrier Part Number HH79NZ014

sensor, in arrangements of 4 or 9 sensors, with total wiring not

to exceed 1000 ft.

CONTROLS INSTALLATION

The VAV units may be used in applications with additional

control features, options, or accessories. Refer to the appropri-

ate accessory installation instructions for more information on

installing that accessory. Unit control box component arrange-

ment is shown in Fig. 20-22. Control options and accessories

available for VAV units are:

To enable reset function, change DIP (dual in-line package)

switch 2 to position ON. (Disconnect control power before

changing DIP switch positions; reconnect power after all

changes have been made.)

CONFIGURATION — Set points for reset operation are

established at potentiometers P7 and P3 (on the reset board).

Potentiometer P7 — Reset temperature set point (temperature

at which reset function will start). Maximum of 80 F, mini-

mum 0° F. Set below normal room cooling set point level to

sense overcooling in the occupied space.

NOTE: It is difficult to accurately set the P7 potentiometer to

the desired set point. Use the procedure below.

•

smoke control modes

differential enthalpy sensor

electric heaters (sizes 034-074 only)

modulating power exhaust

Motormaster^®I control

space temperature reset

night setback thermostat (field-supplied)

single step demand limit

two-step demand limit

inlet guide vanes

variable frequency drive

variable frequency drive remote display kit

Control Wiring — A switch or timeclock (field supplied)

must be wired in to control when unit will go into and out of

Occupied mode. Connect switch or timeclock between termi-

nals 1 and 2 on terminal block 3 (sizes 034-048) or terminal

block 4 (sizes 054-104) in unit control box. See Fig. 23. The

circuit potential is 24 v.

Variable air volume units equipped with warm-up heat re-

quire that room terminals be controlled to go fully open when

unit goes into the Heating mode. Heating interlock relay (HIR)

is provided for this function. The relay is located in the unit

Proper setting of the P7 potentiometer may be made on a re-

sistance basis. The microprocessor initiates reset when it de-

tects a resistance of the thermistor plus the potentiometer of

13,084 ohm. The potentiometer set point may be calculated us-

ing the following formula:

P7_R= 13,084 – T10_R

Where:

P7_R= the desired set point of the P7 potentiometer in ohms

T10_R= the resistance of the T10 thermistor for the desired

set point

Fig. 20 — Unit Control Box Arrangement, Sizes 034-048

034-048: TB3

054-104: TB4

034-048: TB3

054-104: TB4

OPERATING SEQUENCE — If space temperature is above

reset set point (T10 > P7), no reset will occur.

If space temperature is equal to or less that reset set point

(T10 < P7), the LED will display 20 and reset will begin.

Control will automatically adjust leaving air temperature by

the following formula:

OCCUPIED/UNOCCUPIED

SWITCH

MSP = SP + [(P3 - SP) / 3] x (P7 – T10)

where:

MSP = Modified Leaving-Air Set Point

SP = Supply-Air Set Point

NIGHT SETBACK THERMOSTAT

P3 = Maximum Supply-Air Temperature (reset limit)

P7 = Reset Initiation Temperature (reset set point)

T10 = Actual Space Temperature

NOTES:

1. Occ/Unocc switch closes when occupied.

2. Night setback thermostat closes when in night setback heating.

= Ratio for reset (F) (fixed parameter)

Fig. 23 — Occupied/Unoccupied Switch with

Night Setback Thermostat

Table 4 — Thermistor Resistance and Voltage

Drop Characteristics

TEMP

(F)

RESISTANCE

(Ohms)

VOLTAGE

DROP (v)

034-048: TB3

054-104: TB4

31.0

32.0

33.0

34.0

35.0

36.0

37.0

38.0

39.0

40.0

41.0

42.0

43.0

44.0

45.0

46.0

47.0

48.0

49.0

50.0

51.0

52.0

53.0

54.0

55.0

56.0

57.0

58.0

59.0

60.0

61.0

62.0

63.0

64.0

65.0

66.0

67.0

68.0

69.0

70.0

71.0

72.0

73.0

74.0

75.0

76.0

77.0

78.0

79.0

80.0

16813.8

16345.7

15892.2

15452.7

15026.7

14613.9

14213.6

13825.5

13449.2

13084.2

12730.1

12386.6

12053.3

11730.0

11416.1

11111.5

10815.8

10528.7

10250.0

9979.3

9716.5

9461.3

9213.4

8972.6

8738.6

8511.4

8290.6

8076.1

7867.7

7665.1

7468.3

7277.1

7091.2

6910.6

6735.1

6564.4

6398.6

6237.5

6080.8

5928.6

5780.6

5636.8

5497.0

5361.2

5229.1

5100.8

4976.0

4854.8

4736.9

4622.4

3.582

3.553

3.523

3.494

3.464

3.434

3.404

3.373

3.343

3.312

3.281

3.250

3.219

3.187

3.156

3.124

3.093

3.061

3.029

2.997

2.965

2.933

2.901

2.869

2.837

2.805

2.772

2.740

2.708

2.676

2.644

2.612

2.581

2.549

2.517

2.486

2.454

2.423

2.391

2.360

2.329

2.299

2.268

2.237

2.207

2.177

2.147

2.117

2.088

2.058

FIELD

SUPPLIED

POWER

SOURCE

N.O.

N.C.

SIGNAL

TO ROOM

TERMINALS

Fig. 24 — Heat Interlock Relay

034-048: TB3

054-104: TB4

T10

RESET

BOARD

Fig. 25 — Accessory Reset Board

EXAMPLE:

T10 desired set point is 70 F.

T10_Rfrom Table 4 for 70 F is 5929 ohms.

P7_R= 13,084 – 5929

P7_R= 7155 ohms

Using an ohmmeter, set the P7 potentiometer to 7155 ohms

to achieve a reset initiation set point of 70 F.

Potentiometer P3 — Reset limit set point (maximum tempera-

ture value for modified supply air set point). Maximum of 70 F,

minimum 40 F. Set between leaving air set point (P1) and 70 F

(maximum range permitted by control).

RED

BLK

RED

BLK

SIZES 034-048

TB3

RED

BLK

RED

BLK

TO ACCESSORY SPACE

TEMPERATURE RESET

CONTROL BOARD

SIZES 054-104

TB4

SENSOR 1

SENSOR 2

SENSOR 3

SENSOR 4

SPACE TEMPERATURE RESET — 4 SENSOR AVERAGING APPLICATION

SIZES 034-048

TB3

RED

BLK

RED

BLK

RED

BLK

TO ACCESSORY SPACE

TEMPERATURE RESET

CONTROL BOARD

SENSOR 1

SENSOR 3

SENSOR 2

SIZES 054-104

TB4

RED

BLK

RED

BLK

SENSOR 4

SENSOR 5

SENSOR 6

RED

BLK

RED

BLK

NOTE: Sensor part number is HH79NZ014.

SENSOR 7

SENSOR 8

SENSOR 9

SPACE TEMPERATURE RESET — 9 SENSOR AVERAGING APPLICATION

Fig. 26 — Space Temperature Sensor Averaging

Demand Limit — The demand limit function provides a

means to limit the cooling capacity of the VAV unit using an

external discrete switch function. When enabled by the closure

of the external switch, the control will limit the available com-

pressor staging capacity according to user set points established

at demand limit potentiometer(s).

Control Module kit plus installation of 2 field-supplied control

switches (SPST-NO each). This accessory control provides for

a first step reduction of 50% to 100% of the maximum com-

pressor staging; the second step provides for reduction

between 0% and 49%. The exact percentage of capacity reduc-

tion differs depending on the number of capacity steps.

The unit controls support two types of demand limit: single-

step and 2-step control.

When demand limit is active, the LED display will show

code 22 .

SINGLE-STEP DEMAND LIMIT — This function will limit

the total compressor staging based on the ratio of the set point

potentiometer’s wiper arm position to the full scale resistance

of the potentiometer. The exact percentage of capacity reduc-

tion differs depending on the number of capacity steps.

A field-supplied potentiometer and control switch are re-

quired for this function. See installation section for specifica-

tion on potentiometer and field wiring.

INSTALLATION

Single-Step Demand Limit — A 3-wire 5 to 20 K-ohm poten-

tiometer must be field-supplied and installed. A single-

pole normally open switch is also required (field-supplied

and -installed). Locate the potentiometer (designated P4) and

the switch in a suitable location (external from the unit or in the

unit control box).

TWO-STEP DEMAND LIMIT — Two-step demand limit is

provided with the installation of the accessory Demand Limit

Connect the potentiometer end terminals to terminals 8

and 9 on control terminal block TB3 (sizes 034-048) or TB4

(sizes 054-104) (see Fig 27). Connect the switch terminals to

the potentiometer wiper arm terminal and to terminal 10 on

TB3 or TB4.

034-048: TB3

054-104: TB4

To enable demand limit function, change DIP switch 5 to

position ON. (Disconnect control power before changing DIP

switch positions. Reconnect power after all changes have been

made.)

5-20K

POTENTIOMETER

(P4)

Set the potentiometer P4 to desired capacity reduction value.

Two-Step Demand Limit — Install the demand limit control

module (DLCM) according to the installation instructions pro-

vided with the accessory. Disconnect existing leads at connec-

tor J3 on the processor board (see instructions) and connect the

plug from the DLCM harness to connector J3.

SWITCH

Fig. 27 — Single-Step Demand Limit

Connect the field input control power wires (from the exter-

nal control relays) at the terminal strips marked IN1, RTN1,

IN2 and RTN2 (see Fig. 28 and 29).

To enable demand limit function, change DIP switch 5 to

position ON. (Disconnect control power before hanging DIP

switch positions. Reconnect power after all changes have been

made.)

Set the potentiometers DLCM-P1 and DLCM-P2 to desired

capacity reduction values.

Check the operation of demand limit function by using the

Quick Test procedures.

CONFIGURATION

Fig. 28 — Two-Step Demand Limit Module

Single-Step Demand Limit — Field-installed potentiometer

P4 establishes capacity reduction value for demand limit opera-

tion. Set this potentiometer between 0% and 100%. The exact

percentage of capacity reduction differs depending on the num-

ber of capacity steps.

Two-Step Demand Limit — Potentiometer P1 and P2 (locat-

ed on the accessory demand limit control module) establish the

capacity reduction values for each step of demand limit. Set po-

tentiometer DLCM-P1 between 50% and 100%. Set potenti-

ometer DLCM-P2 between 0% and 49%. The exact percentage

of capacity reduction differs depending on the number of ca-

pacity steps.

NOTES:

1. Demand limit switches are field supplied and wired.

2. Demand limit control module terminal blocks will accept up to

12-gage wire.

OPERATING SEQUENCE

Single-Step Demand Limit — If the field control switch to

the wiper arm terminal is open, all capacity stages will be avail-

able (no demand limit in effect). When the field control switch

is closed, the compressor cooling capacity is reduced by the

amount set on potentiometer P4.

is field wiring.

Fig. 29 — 115-Volt Field Wiring to Accessory

2-Step Demand Limit Control Module

Control From Remote Building Management

System (BMS) — The unit control system is not a com-

municating control system, and it cannot be accessed directly

by a DDC (Direct Digital Control) control system (or by a

BACnet communication system). However, it is possible to

control some functions of these units via 4 to 20 mA or 2 to

10 vdc signals and discrete inputs (relay contact closures).

When demand limit is in effect, the LED display will show

code 22 . If a potentiometer setting or input is out of range, the

control will terminate the demand limit function and show

code 84 at the display LED.

Two-Step Demand Limit — If the field control switches are

both open (no power supplied to the Demand Limit Control

Module), all capacity stages will be available (no demand limit

in effect). When control power is supplied to terminal IN1 only

(field switch SW1 closes), the first step of the demand limit is

energized and the compressor cooling capacity is reduced by

the amount set on potentiometer DLCM-P1. When control

power is supplied to terminal IN2 (field switch SW2 closes),

the second step of the demand limit is energized and compres-

sor cooling capacity is reduced by the amount set on potenti-

ometer DLCM-P2.

Functions that can be managed from or accessed from an

external control system include:

•

Occupied/Unoccupied Status

Night Setback Control

Unit Supply Air Set Point Adjustment

Demand Limit (1-stage or 2-stage)

Supply Duct Pressure Set Point Adjustment

External Alarm Signal

Remote control of the economizer cycle on these units is not

recommended. Refer to the Operating Sequence section on

page 35 for a discussion on the economizer cycle operation.

When demand limit is in effect, the LED display will show

code 22 . If a potentiometer setting or input is out of range, the

control will terminate the demand limit function and show

code 84 at the display LED.

OCCUPIED/UNOCCUPIED — The unit control system will

initiate normal occupied mode functions (including Morning

Warm-up, Economizer Minimum Position, and Cooling Cycle)

whenever a contact closure is made that emulates the normal

timeclock contacts. See Fig. 23. (‘‘Occupied/Unoccupied

Switch’’). The contact closure from the BMS must be an iso-

lated contact set, normally open, and suitable for 24 volts AC

pilot duty.

Configuration — Configure as follows:

1. Set DIP switch no. 2 to ON.

2. Adjust manual potentiometer to 12.6 to 12.8 k-ohm.

3. Configure transducer for job site input signal from BMS.

4. Adjust Potentiometer (P3) on the rooftop to MAXIMUM

SASP value (typically 65 to 70 F). The maximum P3 SASP

control limit is 70 F.

NIGHT SETBACK CONTROL — Night setback control is

used to control the space to a set point level that is typically

lower than during normal occupied periods (Heating Only

mode). Some applications also require a limitation on the max-

imum space temperature during unoccupied periods (Cooling

mode). Both modes are possible by closing the same contacts

used in the Occupied/Unoccupied control, or by installing a

dedicated contact set in parallel with the Occupied/ Unoccu-

pied control contacts, and using the BMS space temperature

sensing system and its logic to determine when to initiate unit

operation.

Operation — Unit will initiate SASP Reset (adjust configured

SASP upward) when the sum of the resistance (fixed resistance

+ potentiometer + transducer) exceeds 13.1 k-ohm. Once reset

is initiated, full range of reset (P3 setting minus configured

SASP) will be reached with 500-ohm increase in transducer re-

sistance (TR).

During Reset mode operation, Code 21 will appear on unit

display board.

Formula:

MSP = SASP +

Once the unit operation has been initiated by the BMS con-

tact closure, the unit operates in its normal occupied mode

manner, initiating morning warm-up if needed (as sensed by re-

turn air temperature to the unit) or cooling (controlling to cur-

rent SASP value). The Night Setback Control contacts will in-

terrupt normal unit operation when the BMS senses that space

temperatures have returned to unoccupied set point levels, and

the unit will shut down normally.

(P3 — SASP)

(3)

(0.6 F)

(100 ohm)

X (TR — R@13.3)

[

]

MSP: Modified SASP (SASP plus Reset)

TR: Resistance at transducer

R@13.1: TR required to reach 13.1 k-ohm start level

DEMAND LIMIT (1-STAGE OR 2-STAGE) — Both of the

Demand Limit functions on the units rely on external switches

to initiate the reset functions. Contact closures by the BMS can

be used in place of these switches. Contacts must be isolated

and suitable for 115-vac pilot duty operation.

For Single-Step Demand Limit, emulate function of switch

SW with contact closure controlled by the BMS. Set potenti-

ometer P4 manually at the unit control box. Alternatively, po-

tentiometer P4 might also be emulated by a variable resistance

transducer, with the BMS now able to adjust the amount of de-

mand limit.

For 2-Step Demand Limit, install the accessory Demand

Limit Control Module (DLCM) according the instructions on

page 18. Replace switch functions Switch 1 and Switch 2 with

contact closures controlled by the BMS (see Fig. 29).

Follow unit control configuration instructions in the De-

mand Limit section on page 18.

The contact closure from the BMS must be an isolated con-

tact set, normally open, suitable for 24 volts AC pilot duty.

NOTE: If the rooftop unit is equipped with a VFD and night

setback cooling operation is intended, the fan system must be

controlled to permit FULL SUPPLY FAN AIR DELIVERY

during unoccupied cooling operation. This is most conve-

niently attained by replicating the HIR relay function of the

rooftop unit. An HIR control sequence will force all room ter-

minals to their minimum heating CFM position, thus assuring

adequate airflow through the rooftop unit during night setback

cooling operation. During night setback cooling operation, the

return-air temperature (RAT) will be well above normal levels.

The higher RAT means that the air temperature leaving the

evaporator coil will also be well above normal levels. This sit-

uation is interpreted by the unit control system as a demand for

additional cooling stages. The unit control responds to this

demand by bringing on more stages, until typically all stages

are active. If the VFD is not working in-step with the refrigera-

tion system demand, it is possible to produce low suction pres-

sures and local frosting on the evaporator coil during the night

setback cooling operation.

UNIT SUPPLY AIR SET POINT ADJUSTMENT — The

minimum Supply Air Set Point (SASP) temperature is estab-

lished by the setting at Potentiometer P1 on the unit display

board (see Fig. 6). The control point can also be adjusted

upward by emulating the function of the accessory Space Tem-

perature Reset package. The BMS can be used to cause this

reset by adjusting the resistance value in a variable resistance

transducer with a 4 to 20 mA or 2 to 10 vdc signal generated

by the BMS.

SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT

— Supply duct pressure set point adjustment from a remote

BMS is possible when the unit has been equipped with a fac-

tory-option VFD (variable frequency drive). There are two

methods available:

•

Direct 4 to 20 mA signal

DDC direct to the VFD

Direct 4 to 20 mA Signal — During normal unit operation,

the factory-installed VFD receives a 4 to 20 mA signal from

the Duct Pressure (DP) transducer which indicates current sup-

ply duct pressure. The VFD then determines the appropriate

fan speed (using its internal PID logic feature) and adjusts its

output to the supply fan motor to suit. It is possible to emulate

this 4 to 20 mA control signal by the BMS, which will transfer

control of the VFD to the BMS.

This emulation requires the following field-supplied parts:

•

Variable resistance transducer (Kele RES-1 or equiva-

lent, range 0 to 1000 ohms)

Series resistance with potentiometer, suitable for manual

adjustment to 12.5 to 13.0 k-ohms total resistance

NOTE: When providing a direct 4 to 20 mA signal to the VFD

from a BMS with DP logic, disable the PID (proportion inte-

grated derivative calculation process) feature of the VFD.

DDC Direct to the VFD — Several accessory interface

boards are available for the VFDs that permit direct communi-

cation between the VFD and several BMS communication sys-

tems. Contact your Carrier representative for information on

selecting an appropriate accessory interface board and the

name of the local service office (for sale and installation of the

accessory boards).

Field Connections (see Fig. 30) — Connect fixed resistance

with manual potentiometer and variable resistance transducer

in series.

Connect wiring to rooftop unit at:

Size 034-044: TB3-12 and TB3-15

Size 054-104: TB4-12 and TB4-15

034-048: TB3

054-104: TB4

EXTERNAL ALARM SIGNAL — The unit controls provide

an external alarm status signal via a 115-vac output signal at

the relay board J5, available at TB2-4 and TB2-5 (common).

This signal can be forwarded to the BMS by adding a signal

relay at the alarm output, placing its coil across terminals TB2-

4 and TB2-5 and using its contacts to control a discrete input to

the BMS (see Fig. 31).

TRANSDUCER

BMS

CONTROL

(4 TO 20 MA

2 TO 10 VDC

SIGNAL)

The alarm signal output is energized when any of the diag-

nostic codes is tripped.

REMOTE ECONOMIZER CONTROL — Economizer con-

trol is tightly integrated into the unit’s capacity control algo-

rithms and diagnostic routines. Consequently, control

modifications that interfere with this standard operating

sequence are not recommended.

LEGEND

—

Manual Potentiometer

Fixed Resistor

Field Wiring

Fig. 30 — Remote SASP Wiring

Economizer position is determined by the unit processor

board based on current outdoor air enthalpy status and cooling

capacity demand. The economizer damper actuator is a floating

point device with an internal brake and spring return. Its posi-

tion is determined by the sequencing of relays EOR (Econo-

mizer Open Relay) and ECR (Economizer Close Relay). The

economizer’s current position is sensed by the processor board

through position feedback potentiometer P2.

TB2

LIGHT

Whenever the economizer position potentiometer signal is

not consistent with the processor board’s commanded position,

a fault condition is determined by the processor board and an

alarm signal is initiated. The processor board also attempts to

return the economizer damper to its fully closed position dur-

ing this fault condition by energizing the ECR relay.

RELAY

Any attempt to effect an external control of the economizer

actuator will lead to an alarm condition and an automatic re-

sponse by the unit control to attempt to close the dampers.

SIGNAL TO BMS

Smoke Control Modes — It is common practice to use

rooftop units for aid in building smoke control in the event of a

building fire. The available functions include: Fire Shutdown,

Pressurization, Evacuation, and Smoke Purge. These functions

are enhanced when multiple rooftop units are used to zone a

building.

Implementation of the various Smoke Control modes on

these units requires the installer to modify the unit wiring to

add contacts (via either manual switches or relays) that will se-

lectively interrupt and override standard factory control se-

quences. See Table 5.

Smoke control mode Pressurization requires the economiz-

er function. Evacuation and Smoke Purge modes require both

economizer and power exhaust functions. Both functions are

standard features on 48FM and 50FM,FS units. These func-

tions require factory-installed options, field-installed accesso-

ries and/or field-supplied exhaust systems on 48FK,JK and

50FK,FY,JK,JY units. Consult price pages for specific details.

FIRE SHUTDOWN MODE — Fire Shutdown mode termi-

nates all unit operation (cooling, heating, supply fan and power

exhaust). This mode prevents recirculation of contaminated air

back into the space or the admission into the space of unsuit-

able outside air.

LEGEND

—

Fixed Resistor

Factory Wiring

Field Wiring

Fig. 31 — External Alarm Indication

•

running the supply fan (optional inlet guide vanes open

or optional VFD [variable frequency drive] at normal

duct static pressure set point)

shutting off the power exhaust fans (Standard on 48FM

and 50FM,FS units. Factory-installed option or field-

installed accessory on 48FK,JK and 50FK,JK units)

•

This allows the space to be overpressurized relative to adja-

cent zones and prevents or slows entry of smoke into this space

from adjacent zones.

EVACUATION MODE — Evacuation mode removes smoke

or undesirable air from interior spaces without reintroducing

unsuitable air. The economizer and power exhaust are required

for this function. The economizer and power exhaust are

standard on 48FM and 50FM,FS units. The economizer is a

factory-installed option and the power exhaust is a factory-

installed option or field-installed accessory on 48FK,JK and

50FK,JK units. Evacuation is accomplished by:

•

turning supply fan off

PRESSURIZATION MODE — Pressurization mode is

intended to keep smoke out of a zone. The economizer is

required for this function. The economizer is standard on

48FM and 50FM,FS units. The economizer is a factory-

installed option on 48FK,JK and 50FK,FY,JK,JY units. Pres-

surization is accomplished by:

opening the economizer

running the exhaust fans

opening the exhaust dampers

•

opening the economizer

SMOKE PURGE MODE — Smoke Purge mode removes

smoke from the interior spaces and replaces it with fresh out-

side air. The economizer and power exhaust are required for

this function. The economizer and power exhaust are standard

on 48FM and 50FM,FS units. The economizer is a factory-

installed option and the power exhaust is a factory-installed

option or field-installed accessory on 48FK,JK and 50FK,JK

units. Smoke purge is accomplished by:

CONFIGURATION — No set points required for Smoke Con-

trol modes. Modes are activated by energizing all switches

appropriate for each Smoke Control mode.

OPERATING SEQUENCE

Fire Shutdown — At command from the field switches (see

Table 5), all unit operation (cooling, heating, supply fan and

power exhaust) will terminate.

Pressurization — At command from the field switches for

Pressurization mode (see Table 5):

1. Economizer dampers will open.

2. The HIR function will energize, opening room terminals

to full-open (heating) positions.

3. Supply fan will run. (If equipped with IGV: control vanes

will open. If equipped with VFD: the VFD will control to

duct static set point or best available with all terminals

open.)

•

turning supply fan on

opening the economizer

running the exhaust fans

opening the exhaust dampers

INSTALLATION — To enable one or more of the possible

smoke control modes available with these units, determine the

switches required for the desired mode(s) from Table 6, field-

supply and install the appropriate switches and field wire per

Fig. 32. Switch functions are shown in Table 7.

4. Power exhaust dampers (if equipped) will close.

5. Power exhaust fans (if equipped) will turn off.

Table 5 — Smoke Control Modes

Evacuation — At command from the field switches for Evacu-

ation mode (see Table 5):

1. Supply fan will turn off.

2. Economizer dampers will open.

3. Exhaust fans will run at maximum capacity.

4. Exhaust dampers will open.

Smoke Purge — At command from the field switches for

Smoke Purge mode (see Table 5):

MODE

FUNCTION

Fire

Pressur-

ization

Smoke

Purge*

Open/On

Open

Evacuation*

Shutdown

Supply Fan

IGV/VFD†

Economizer

Return Air

Damper

Exhaust

Fans

Off

—

Closed

Off

—

Open

Open/On

Open

Off

Closed

Off

Closed

1. Economizer dampers will open.

2. The HIR function will energize, opening room terminals

to full-open (heating) positions.

Exhaust

Damper

Closed

Open

LEGEND

3. Supply fan will run. (If equipped with IGV: Control vanes

will open. If equipped with VFD: the VFD will control to

duct static set point or best available with all terminals

open.)

4. Exhaust fans will run at maximum capacity.

5. Exhaust dampers will open.

IGV — Inlet Guide Vane

VAV — Variable Air Volume

VFD — Variable Frequency Drive

*Power exhaust function required for this mode.

†Applicable to VAV units with appropriate options.

Table 6 — Smoke Control Switches Required for Each Mode

EVACUATION

(Modulating Power

Exhaust)

FIRE

SHUTDOWN

SMOKE

PURGE

PRESSURIZATION

SW-1

SW-2

SW-1

SW-2

SW-4

SW-5

SW-6

SW-1

SW-2

SW-3

SW-5

SW-6

SW-7

SW-8*

SW-1

SW-2

SW-3

SW-4

SW-9A/B

*Not required on 48FM and 50FM,FS units (high capacity power exhaust units).

NOTE: All switches are shown in “as installed” (power OFF or deenergized) position. In these

positions, none of these modes will be activated; normal unit operation is permitted by the base

unit controls. To initiate any mode, all switches listed under this mode in the table must be ener-

gized, causing the depicted contact position to change from depicted positions to energized posi-

tions. Switches may be manually or electrically operated.

Table 7 — Switch Functions

SWITCH

NUMBER

CONFIGURATION

VOLTAGE

FUNCTION

SW-1

SW-2

SW-3

SW-4

SW-5

SW-6

N.C.

N.O.

N.C.

N.O.

115

Deenergize 115-v (OFC, Comp, IFC, Electric Heaters)

Deenergize TRAN7 (Process Board)

Energize EOR (Open Economizer Outside Air Dampers)

Energize IFC and CR-3 (IGV/VFD)

Isolate IFC and PEC for Separate Operation

Energize PEC (Power Exhaust)

Open PED at DPS (48FK,JK and 50FK,JK Units) Force Power Exhaust VFD

to Maximum Speed (48FM and 50FM,FS Units)

Block Auto-Close at DPS (Due to Low BP)

SW-7

SW-8*

N.O.

N.C.

A: N.O.

B: N.C.

SW-9A/B

115 max

Signal Room Terminals to Open (HIR1)

*Not required on 48FM and 50FM,FS units (units with high capacity power exhaust).

LEGEND

BP — Building Pressure

DPS — Differential Pressure Switch

EOR — Economizer Open Relay

HIR — Heat Interlock Relay

IFC — Indoor Fan Contactor

IGV — Inlet Guide Vane

N.C. — Normally Closed

N.O. — Normally Open

PEC — Power Exhaust Contactor

PED — Power Exhaust Damper

OFC — Outdoor Fan Contactor

VFD — Variable Frequency Drive

INLET GUIDE VANES — The tubing for the duct pressure

Air Pressure Tubing — Before options such as inlet

guide vanes (IGV), variable frequency drive (VFD), and/or

modulating power exhaust can operate properly, the pneumatic

tubing for pressure sensing must be installed. Use fire-retardant

plenum tubing (field-supplied). Tubing size depends on type of

control device (see Table 8 below). Tubing must be run from

the appropriate sensing location (in the duct or in the building

space) to the control device location in the unit.

(DP) control option should sample supply duct pressure about

²/₃of the way out from the unit in the main trunk duct, at a

location where a constant duct pressure is desired.

The inlet guide vanes are controlled by a differential pres-

sure switch (DPS). On sizes 034-048, the DPS is located in the

auxiliary control box at the economizer end of the unit (see

Fig. 33). On sizes 054-104, the DPS is located in the supply fan

section. See Fig. 34. Use a nominal ³/₈-in. plastic tubing.

SUPPLY FAN VARIABLE FREQUENCY DRIVE — The

tubing for the duct pressure (DP) control option should sample

supply duct pressure about ²/₃of the way out from the unit in

the main trunk duct, at a location where a constant duct pres-

sure is desired.

Table 8 — Tubing Size

NOMINAL TUBE

OPTION

UNITS

ALL

SIZE (in.)

Inlet Guide Vanes (IGV)

The duct pressure is sensed by a pressure transducer. The

pressure transducer output is directed to the VFD. On 034-048

units the DP transducer is located in the auxiliary control box.

On 054-104 units, the DP transducer is located in the supply

fan section. See Fig. 34. Use a nominal ¹/₄-in. plastic tubing.

Supply Fan Variable

ALL

Frequency Drive (VFD)

FK,FKX,JK,JKX

FM,FS

Modulating Power Exhaust

054-104 UNITS

034-048 UNITS

TB2

SW-1

TB2

SW-1

TB2

REMOVE JUMPER

TB2

SW-2

TB2

SW-2

TB2

REMOVE JUMPER

SW-3

SW-4

TB3

SW-3

SW-4

TB4

TB2

SW-5

TB2

SW-5

TB2

REMOVE JUMPER

TB2

SW-6

TB2

SW-6

SW-9A

TB3

SW-9A

TB4

HIR

TB4

TB3

SW-9B

TB3

TB4

SW-9B

REMOVED FROM TB3-7

REMOVED FROM TB4-7

48FK, JK AND 50FK, JK034-104 UNITS

SW-7

DPS

SW-8

WHT

VIO

REMOVED

FROM C-DPS

GRA

48FM, AND 50FM, FS034-104 UNITS

SW7

PEVFD

LEGEND

DPS

HIR

— Differential Pressure Switch

— Heat Interlock Relay

PEVFD — Power Exhaust Variable Frequency Drive

— Switch

— Terminal Block

Fig. 32 — Smoke Control Wiring

MODULATING POWER EXHAUST

48FK,JK and 50FK, JK Units — The tubing for the building

pressure control (achieved via the Modulating Power Exhaust

option/accessory) should sample building pressure in the area

near the entrance lobby (or other appropriate and sensitive

location) so that location is controlled as closely to design pres-

sures as possible.

A differential pressure switch (DPS) is used to control the

actuator on the modulating discharge damper in exhaust fan

no. 1. The building pressure (BP) DPS is located in the auxilia-

ry control box of the unit. See Fig. 33 and 35. Use a nominal

³/₈-in. plastic tubing.

For instructions on adjusting BP control set points, refer to

Start-Up, Modulating Power Exhaust section in this book.

48FM and 50FM,FS Units — The tubing for the building

pressure control (achieved through the High Capacity Modu-

lating Power Exhaust) should sample the building pressure in

the area near the entrance lobby (or other appropriate and sen-

sitive location) so that the location is controlled as closely to

design pressures as possible.

Fig. 33 — Modulating Power Exhaust and Inlet

Guide Vane Differential Pressure Switch

(Sizes 034-048)

A building pressure transducer (BPT) is used to sense the

building pressure and supply a 4 to 20 mA signal to the power

exhaust VFD (PE VFD) which controls the speed of exhaust

fan motor no. 1 and stages on/off power exhaust fan motor

no. 2 to maintain the building pressure. The BPT is located in

the auxiliary control box. Use a nominal ¹/₄-in. plastic tubing.

For instructions on adjusting the BP control set point, refer

to Start-Up, High Capacity Modulating Power Exhaust section

in this book.

START-UP

Initial Check

IMPORTANT: Do not attempt to start unit, even

momentarily, until all items on the Controls Start-Up

Checklist (in installation instructions) and the following

steps have been completed.

Fig. 34 — Inlet Guide Vane Differential

Pressure Switch and Variable Frequency Drive

(Sizes 054-104)

1. Verify unit has been installed per the Installation Instruc-

tions included in the unit installation packet.

2. Verify that all auxiliary components (sensors, controls,

etc.) have been installed and wired to the unit control

boxes per these instructions, the unit Installation Instruc-

tions, and the unit wiring label diagrams.

3. Verify that air pressure hoses (static, duct, etc.) are prop-

erly attached, routed, and free from pinches or crimps that

may affect proper control operation.

4. Set any control configurations that are required (field-

installed accessories, etc.). The unit is factory configured

for all appropriate factory-installed options with the ap-

plicable controls programmed to the default values.

5. Check and adjust unit set points. See Table 9.

6. Check tightness of all electrical connections.

Fig. 35 — Modulating Power Exhaust Differential

Pressure Switch (Sizes 054-104)

7. Perform quick test (see Quick Test Program section on

page 31).

Table 9 — Potentiometer Inputs and Ranges

CONTROL

POTENTIOMETER

DESCRIPTION

LOCATION

VALID

DEFAULT VALUE

45 F if -22 F < P1 < 45 F

RANGE

Supply Air

Set Point

Economizer

Position

Display

Board

Economizer

Motor

Accessory

Board

P2*

45 to 70 F

0 to 100%

0 to 80 F

70 F if P1 > 70 F OR IF P1 < -22 F

None (0 if P2 is bad)

Reset Limit

None (limited to 70 F maximum)

None

Demand Limit,

Single-Step

P4†

Main Control Box

0 to 100%

DLCM-P1

DLCM-P2

DLCM Board

50 to 100%

0 to 49%

None

Demand Limit,

2-Step

Minimum Economizer

Position

P5*

Accessory Board

Reset Board

0 to 100%

40 to 80 F

40 to 100 F

None

40 F if 0° F < P6 < 40 F OR IF P6 < 95 F

OR IF P6 < 0

80 F if 80 F < P6 < 95 F

Warm-Up

Set Point

Reset

Temperature

P7**

None

*Optional factory-installed economizer is required. Potentiometer P2 is not a set point.

†Accessory two-step demand limit module is required (which has 2 potentiometers), or a 5 to 20 k-ohm

field-supplied potentiometer is required for single-step demand limit.

**Accessory temperature reset is required.

NOTE: Potentiometers P1-P6 input data to pin terminal connector J3.

Potentiometer P7 inputs data to pin terminal connector J1.

Configuration Header — The configuration header is a

Table 11 — Configuration Header Jumpers

series of 8 small wires that are broken (open circuit) or unbro-

ken (closed circuit) in a pattern to indicate several unique char-

acteristics of the unit. The configuration header is factory set

and should not be changed; changing the factory setting may

cause the unit to malfunction.

JUMPER

NUMBER

FACTORY

SETTING

FUNCTION

Unit Type

MEANING

1,2

3,4,5

VAV Rooftop Unit

2 Compressors

TXV

Qty Compressors

Expansion Valve

Power Frequency

Not Used

Before start-up, visually check the configuration header

against the factory setting for the unit size. See Table 10 for

factory settings. See Table 11 for purpose for each jumper.

60 Hz

No Significance

LEGEND

Thermostatic Expansion Valve

Table 10 — Configuration Header and

DIP Switch Factory Settings

TXV

—

VAV — Variable-Air Volume

—

Broken Jumper (open circuit)

Unbroken Jumper (closed circuit)

UNIT SIZES

034-038,

048-088

UNIT SIZE

044

UNIT SIZE

104

JUMPER OR

SWITCH NO.

Header Switch Header Switch Header Switch

Position Position Position Position Position Position

DIP Switches — The DIP switches configure the unit for

several factory-installed options and field-installed accessories,

plus factory unloaders. The DIP switches are located under a

plastic enclosure which must be removed for access. See

Fig. 1. The switches can be field adjusted. Switches must only

be adjusted when control power is deenergized. See Table 12

for DIP switch purposes and Table 10 for factory settings of the

switch positions.

Off

On/Off*

Off

On/Off*

Off

On/Off*

Off

LEGEND

DIP

—

Dual, In-Line Package

Disconnect control power before changing the settings of

the DIP switches. To disconnect control power, open the

control circuit breaker.

Broken Jumper (open circuit)

Unbroken Jumper (closed circuit)

*Depending on factory-installed options or field-installed accessories.

DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset

Type. Factory setting is OFF. Do not change.

DIP SWITCH NO. 2 — SASP Reset Enabled. Factory setting

is OFF (no SASP reset enabled). If SASP reset has been

installed, enable it by changing switch position to ON.

DIP SWITCH NO. 3 — Economizer option. If economizer

option has been installed, this switch will be ON. If there is no

economizer installed, this switch will be OFF. For all 48FM

and 50FM,FS units, this switch will be ON. Confirm setting

per Table 10. Change only if in error.

DIP SWITCH NO. 4 — Morning Warm-Up. For 48FK,FM,JK

units, this switch will be ON (morning warm-up enabled). For

50FK,JK units with factory-installed electric heaters, this

switch will be ON. For all other units, this switch will be OFF.

If accessory electric heaters are installed (for 50FK,JK 034-

074 units without plenum option), change this switch to ON.

Potentiometer inputs and ranges are summarized in Table 9.

Information on individual set point potentiometers (including

function, location and range data) are shown below:

SUPPLY AIR SET POINT (Leaving-Air Temperature) (P1)

— This potentiometer establishes the set point for cooling

cycle operation of the VAV unit. The VAV control uses a valid

control range of 45 to 70 F, and the potentiometer has a valid

range of –22 to 70 F. If the set point is between –22 and 45 F,

the control will use a value of 45 F. If the set point is outside

the valid range (less than –22 F or greater than 70 F), an alarm

condition will be signaled and a default value of 70 F will be

used.

ECONOMIZER MINIMUM POSITION (P5) — This potenti-

ometer specifies the minimum opening position for the

optional economizer during running periods. It has both a valid

range and an operational range of 0 to 100%.

SASP RESET TEMPERATURE (P7) — This potentiometer

establishes the space temperature at which the control will ini-

tiate the reset of the SASP (i.e., the unit control begins to raise

the base SASP, to prevent overcooling of the space). The

potentiometer has a valid range of 40 to 100 F. Refer to Space

Temperature Reset section on page 13 for further discussion of

SASP Reset operation.

DIP SWITCH NO. 5 — Demand Limit. Factory setting is OFF

(demand limit not enabled). If Demand Limit (single-step or

2-step accessory) has been installed, change this switch to ON.

DIP SWITCHES NO. 6 AND NO. 7 — Unloader Configu-

ration. These are factory set to match unit size. Confirm set-

tings per Table 12. Change only if in error.

Table 12 — DIP Switches

RESET LIMIT (P3) — Used in conjunction with P7 potenti-

ometer, this potentiometer establishes the maximum tempera-

ture for the modified SASP value during the Reset function.

This potentiometer has a valid range of 0° to 80 F.

DEMAND LIMIT, SINGLE-STEP (P4) — This potentiome-

ter establishes the maximum amount of compressor capacity

permitted by the unit control when single-step demand limit

operation is implemented (by closing contact set to potentiom-

eter wiper arm). This potentiometer is field-supplied and

-installed and will be located in the main control box. The

valid range is 0% to 100%, which is also the operational range.

SWITCH

NO.

SWITCH

POSITION*

FUNCTION

MEANING

Reset

Mode

Space or Outdoor-Air Reset

(DO NOT CHANGE)

Off

Reset

Select

Off

Reset Used

Reset Not Used

Off

Enable Economizer

Disable Economizer†

Economizer

Morning

Warm-Up

Off

Enable Morning Warm-Up**

Disable Morning Warm-Up**

Demand

Limit

Off

Enable Demand Limit

Disable Demand Limit

If the wiper arm is open, all capacity stages can be used.

When the wiper arm is closed, the capacity is reduced by the

amount set on potentiometer P4.

Off, Off

On, Off

Off, On

No Unloaders

1 Unloader

6,7

Unloaders

Not Used

2 Unloaders

Off

No Significance

DEMAND LIMIT, 2-STEP — The accessory 2-step demand

limit control is a 2-potentiometer system. The demand limit

control board (DLCM) accessory board is field-installed in the

main control box; the 2 control potentiometers are located on

the DLCM. Potentiometer DLCM-P1 establishes the maxi-

mum amount of compressor capacity available when SW1 is

closed and has a valid range is 50% to 100%. Potentiometer

DLCM-P2 establishes the maximum amount of compressor

capacity available when SW2 is closed and has a valid range is

0% to 49%.

If no power is supplied to the DLCM, all capacity stages

can be used. When power is supplied to terminal IN1 only, the

first step of demand limit control is energized and the capacity

is reduced by the amount set on potentiometer P1. When power

is supplied to IN2 (or IN1 and IN2), the capacity is reduced by

the amount set on potentiometer P2.

MORNING WARM-UP (P6) — This potentiometer estab-

lishes the set point temperature for the Morning Warm-Up

function. This is the temperature at which the morning warm-

up sequence is terminated and VAV cooling operation begins.

The valid control range is 0° to 95 F, but the control is pro-

grammed to accept a range of 40 to 80 F. If the set point is

between 0° and 40 F, the control will use a value of 40 F. If the

set point is between 80 and 95 F, the control will use a value of

80 F. If the set point is outside the valid range (less than 0° F or

greater than 95 F, an alarm condition will be signaled and a

default value of 40 F will be used.

LEGEND

— Dual, In-Line Package

DIP

*Control circuit breaker must be off before changing the setting of the DIP

switch.

†No economizer.

**And/or electric heat (50FK,JK034-074 units without plenum only).

Adjusting Set Points — Set points for unit operation

are established via potentiometer settings. Set points for Supply

Fan controls are set at the VFD keypad (if installed) or at the

IGV differential pressure switch (DPS1) (if IGV option in-

stalled). Set points for modulating power exhaust (option or ac-

cessory) are set at the differential pressure switch (DPS2).

Set points for high capacity modulating power exhaust

(48FM and 50FM,FS units) are set at the power exhaust VFD

keypad.

Potentiometers — All of the set point potentiometers

must be set before the unit is started in order for the unit to

function properly. Each of the potentiometers has a valid range

that is used by the control. The valid range is defined as the po-

tentiometer’s resistance value that the control will not consider

to be in error. This is usually between 10% and 90% of the po-

tentiometer’s total resistance. The control has been pro-

grammed to accept an operational range for the potentiometer,

which may not be the same as the valid range.

Supply Fan Control with IGV Option — The inlet

guide vane option will modulate the supply fan airflow in order

to maintain the static pressure in the supply duct. The set point

for duct static pressure is established at the differential pressure

switch for the IGV control.

SIZE 034-048 UNITS — The inlet guide vane differential

pressure switch is located in the auxiliary control box mounted

in the corner under the side air hood that is next to the access

door marked FILTER SECTION. To gain access to this control

box, remove the auxiliary control box cover. When replacing

cover, be sure to properly secure it in order to prevent water

from being drawn into the unit. See Fig. 36 and 37.

SIZE 054-104 UNITS — The inlet guide vane differential

pressure witch is mounted on an upright located behind the

supply-fan motor. See Fig. 36-38.

The IGV differential pressure switch has an adjustable set

point range of 1.1 to 3.5 in. wg. and a factory setting of

1.9 in. wg.

*The inlet guide vane differential pressure switch for the 034-048

units is located in the back of the unit in the auxiliary control box. Its

location is not shown in this figure.

To adjust set point, turn set point adjusting screw (see

Fig. 39) clockwise to decrease set point and counterclockwise

to increase set point. This switch also has an adjustable null

span. The null span is the pressure change that can be made

without contacts opening or closing. It is adjustable from

0.06 in. wg to 0.17 in. wg when set point is at minimum posi-

tion (1.1 in. wg) and 0.11 in. wg to 0.31 in. wg when set point is

at maximum position (3.5 in. wg). To adjust null span, turn a

null adjusting screw (Fig. 39) clockwise to decrease span and

counterclockwise to increase span. All switches leave factory

with null span set at maximum position. The smaller the null

span, the closer the pressure will be maintained to desired set

point.

Fig. 36 — Inlet Guide Vane Motor,

50FK,JK034-074 Units

Supply Fan Control with VFD Option — The VFD

option will modulate Supply Fan motor (and thus wheel) speed

to maintain the static pressure in the ductwork. Set point for the

VFD option is set at the VFD, using the display keyboard on

the front of the VFD enclosure. See Fig. 40.

NOTE: The VFD will always provide the proper phase

sequence to the supply-fan motor. The supply-fan motor oper-

ates in proper rotation regardless of the phase sequence to the

unit. If, upon start-up, the outdoor fans operate backwards but

the supply fan operates in the correct direction, reverse any two

leads to the main terminal block. All fans will then operate in

the correct direction.

*The inlet guide vane differential pressure switch for the 034-048

units is located in the back of the unit in the auxiliary control box. Its

location is not shown in this figure.

Fig. 37 — Inlet Guide Vane Motor, 48FK,JK, 50FJ,JY,

and 50FJX,FJY,FKX,FKY034-074 Units

The supply duct pressure transducer has a range of 0.0 to

5.0 in. wg. Its output is a 4 to 20 mA signal, scaled to this

range. The VFD translates this 4 to 20 mA input signal to rep-

resent a frequency value over the control range of 0 to 60 Hz.

The factory default set point is 30 Hz, representing a supply

duct pressure of 2.5 in. wg.

Factory-installed optional VFD is located near the supply

fan and motor. During any service work or programming at

the VFD, operation of the fan and motor is not desirable

and may be dangerous. Either disable the unit supply fan

(following instructions below) or install the accessory VFD

remote display accessory.

Fig. 38 — Inlet Guide Vane Motor,

Size 078-104 Units

DISABLE SUPPLY FAN MOTOR — To disable the supply

fan motor and change programming of VFD set point:

CAPACITOR

1. Turn off Indoor Fan Circuit Breaker (IFCB). This will re-

move power to the VFD.

NULL

ADJUSTMENT

COM

N.C.

N.O.

Ensure the “CHARGE” lamp on the VFD is unlit. This

may take up to 4 minutes. The “CHARGE” lamp indicates

that the main capacitors in the VFD are charged. Internal

components of the VFD should not be touched until the

“CHARGE” lamp is completely out. Electrical shock can

cause injury or death.

SET

2. Wait for the VFD display to go blank and remove VFD

cover without touching any interior components.

POINT

ADJUSTMENT

3. Ensure that the charge indicator lamp is out which indi-

cates that the VFD is discharged. The lamp is located on

the upper right hand corner of the terminal block. If still

lit, wait until lamp goes completely out. This may take

several minutes.

4. Remove jumper from terminals ST-CC (see Fig. 41) and

replace VFD cover.

5. Turn on IFCB.

6. The drive output will now be disabled but the program-

ming can be changed.

SET

POINT

INDICATOR

LEGEND

COM — Common

N.C. — Normally Closed

N.O. — Normally Open

Fig. 39 — Differential Pressure Switch for Inlet

Guide Vane and Static Pressure Control Option

and Modulating Power Exhaust Option

7. Change VFD set point according to Table 14 shown

on page 30.

8. Once the program changes are completed, turn off IFCB.

PERCENT

SECONDS

KW/AMPS/VOLTS

9. Wait for the VFD display to go blank and remove VFD

cover without touching any interior components.

10. Ensure that the charge indicator lamp is out which indi-

cates that the VFD is discharged. The lamp is located on

the upper right hand corner of the terminal block. If still

lit, wait until lamp goes completely out. This may take

several minutes.

SETUP

PROGRAM

RUN

MONITOR

11. Replace jumper to terminals ST-CC.

12. Replace VFD cover.

13. Turn on IFCB to enable the drive.

STOP

READ

For additional information on the VFD (including basic

troubleshooting, factory jumper arrangements, and Carrier fac-

tory defaults programming), refer to Troubleshooting, Supply

Fan Variable Frequency Drive section (page 52).

WRITE

RESET

LOCAL/REMOTE

MANUAL/AUTO

IMPORTANT: The Carrier factory default values for the

VFD may be different than the default values of the

manufacturer. Refer to the Service section when check-

ing default values.

SPEED CTRL

RUN MODE

Fig. 40 — Variable Frequency Drive Keypad

P24 RES RR

S1 S2 S3 S4 RCH P24 LOW LOW

CC RX PP IV FP FLC FLB FLA

DETERMINE VFD SET POINT — The unit of measure for

the Duct Pressure set point at the VFD is output frequency

(Hz), corresponding to the desired DP set point (DPSP) in

inches of water gage (in. wg). To convert desired DPSP into

the VFD set point, refer to Table 13. Locate the pressure value

in the table closest to the desired DPSP for this installation

and use the corresponding VFD set point (Hz) value. If neces-

sary, interpolation between duct static pressure values is

permissible.

FM AM CC

REMOVE

JUMPER

Fig. 41 — Jumper Removal to Disable Motor

ADJUST VFD SET POINT — To adjust the VFD set point,

the VFD must be powered; however, since it is located near the

supply fan and motor, operation of the fan and motor is not

desirable. Either disable the Supply Fan or install the accessory

VFD remote display accessory.

Table 13 — VFD Set Point (Frequency Command) for Duct Pressure

PRESSURE

(in. wg)

CONTROL SIGNAL

(mA)

PRESSURE

(in. wg)

VFD SET POINT

(Hz)

CONTROL SIGNAL

(mA)

VFD SET POINT (Hz)

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

4.0

4.8

5.6

6.4

7.2

8.0

8.8

9.6

2.00

2.25

2.50

2.75

3.00

3.25

3.50

10.4

11.2

12.0

12.8

13.6

14.4

15.2

Table 14 — Changing the VFD Set Point (Frequency Command)*

KEY OPERATION

LED MESSAGE

EXPLANATION

Standard Monitor Mode (output frequency). If drive is disabled, display

will read “OFF”. If enabled, display will show current output frequency

XX.X or OFF

↓

↓↑

60.0

45.0 (flashing)

Pressing arrow key once will display the current frequency set point

Pressing up/down arrow keys changes the desired set point

When the Read/Write key is pressed, the parameter name (FC) and the new value (45.0)

FC and 45.0 (flashing) will alternately flash to indicate that the new value has been stored. After 2 cycles, the display will

return to the standard monitor mode.

READ

WRITE

Standard Monitor Mode (output frequency). If drive is disabled, display

will read “OFF”. If enabled, display will show current output frequency

XX.X or OFF

*Choose set point from Table 13 according to desired duct pressure or Table 15 according to desired building pressure.

power exhaust fan motor no. 2 to maintain the building pres-

Modulating Power Exhaust (Option or Acces-

sory) (48FK,JK and 50FK,JK Units) — The Mod-

ulating Power Exhaust system will maintain space pressure by

modulating power exhaust fan no. 1 and staging power exhaust

fan no. 2. Building pressure set point is established at the mod-

ulating power exhaust differential pressure switch (DPS).

sure. The set point for the building pressure control is set at the

power exhaust VFD using the keyboard on the front of the

power exhaust VFD enclosure. See Fig. 40.

NOTE: The VFD will always provide the proper phase

sequences to the power exhaust fan motor.

SIZE 034-048 UNITS — The modulating power exhaust dif-

ferential pressure switch is located in the auxiliary control box

mounted in the corner next to the power exhaust motor door.

To gain access to this control box, remove the auxiliary control

box cover. When replacing cover, be sure to properly secure it

in order to prevent water from being drawn into the unit. See

Fig. 33.

SIZE 054-104 UNITS — The modulating power exhaust dif-

ferential pressure switch is mounted below the auxiliary con-

trol box next to the access door labeled FILTER SECTION.

See Fig. 35.

DIFFERENTIAL PRESSURE SWITCH — The modulating

power exhaust DPS has a set point range of 0.5 in. wg to

–0.5 in. wg. Factory setting is +0.1 in. wg. To adjust set point,

turn set point adjusting screw (see Fig. 39) clockwise to

decrease set point and counterclockwise to increase set point.

This switch also has an adjustable null span. The null span is

the pressure change that can be made without contacts opening

or closing. It is adjustable from 0.06 in. wg to 0.14 in. wg when

set point is at minimum position (–0.5 in. wg) and 0.07 in. wg

to 0.14 in. wg when set point is at maximum position

(+0.5 in. wg). To adjust null span, turn null adjusting screw

(Fig. 39) clockwise to decrease span and counterclockwise to

increase span. All switches leave factory with null span set at

maximum position. The smaller the null span, the closer the

pressure will be maintained to desired set point.

The exhaust fan motor operates in proper rotation regardless

of the phase sequence to the unit. If, upon start-up, the outdoor

fans operate backwards but the exhaust fan operates in the cor-

rect direction, reverse any two leads on the main terminal

block. All fans will then operates in the correct direction.

The building pressure transducer has a range of –0.5 to

+0.5 in. wg. The output is a 4 to 20 mA signal, scaled to this

range. The VFD translates the 4 to 20 mA signal to represent a

frequency value over the control range of 0 to 60 Hz. See

Table 15. The set point for duct pressure control is established

at the power exhaust VFD keypad in terms of Hz. The factory

default set point is 30 Hz, representing a building pressure of

0.0 in. wg.

DETERMINE POWER EXHAUST VFD SET POINT —

The unit of measure for the building pressure set point (BPSP)

at the power exhaust VFD is output frequency (Hz), represent-

ing the desired BPSP (in. wg). To convert the desired BPSP

into the power exhaust VFD set point, refer to Table 15. Locate

the pressure value in the table closet to the desired BPSP for

the application and use the corresponding set point (Hz) value.

If necessary, interpolation between duct static pressure values

is permissible.

ADJUST PE VFD SET POINT — To adjust the PE VFD set

point, the PE VFD must be powered. Since it is located in the

indoor section of the unit, use caution to ensure that the service

access door is blocked open and will not close suddenly.

High Capacity Power Exhaust (48FM and

50FM,FS Units) — The power exhaust VFD will modu-

late the power exhaust fan motor no. 1 speed and stage (on/off)

Change PE VFD set point according to Table 14.

Table 15 — PE VFD Set Point (Frequency

display board will be energized. This indicates that control sys-

tem is ready to run quick test program.

Command) for Building Pressure

VFD

SET POINT

(Hz)

CONTROL

SIGNAL

(mA)

VFD

SET POINT

(Hz)

CONTROL

SIGNAL

(mA)

IMPORTANT: Do not allow unit control circuit to

remain energized with 20 showing on display for more

than 2 minutes. If display button is not pressed within

this time period, control will attempt to start unit.

PRESSURE

(in. wg)

PRESSURE

(in. wg)

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.0

3.0

4.00

4.80

5.60

6.40

7.20

8.00

8.80

9.60

10.40

11.20

0.00

–0.05

–0.10

–0.15

–0.20

–0.25

–0.30

–0.35

–0.40

–0.45

–0.50

30.0

33.0

36.0

39.0

42.0

45.0

48.0

51.0

54.0

57.0

60.0

12.00

12.80

13.60

14.40

15.20

16.00

16.80

17.60

18.40

19.20

20.00

6.0

9.0

For each step of the 33-step program, display button must

be pressed twice. On first press, step number is displayed;

second press initiates required action and appropriate code is

displayed.

NOTE: The step number is a numeral followed by a decimal

point (a 2-digit number has a decimal point after each

numeral). The action code number is one or 2 digits with no

decimal point(s).

12.0

15.0

18.0

21.0

24.0

27.0

IMPORTANT: Once quick test is initiated, display but-

ton must be pressed at least once every 10 minutes for

control to remain in Quick Test mode. If button is not

pressed within this time, control will attempt to start the

unit.

START UNIT

To start unit:

To recheck any step in quick test program, control must be

recycled by turning unit control switch off for a few seconds,

and then turning it back on again. Restart quick test program as

described above and proceed through quick test steps. Press

display button twice for each step until step to be rechecked is

reached.

1. Close the unit-mounted ON/OFF switch (located in the

main control box).

2. Close the field-supplied and -installed timeclock (or con-

trol) switch (contacts located at Terminals 1 and 2 (TB3

for 034-048, TB4 for 054-104).

The quick test program is divided into 3 sections as de-

scribed below and shown in Tables 16-18.

1. Quick Test Steps 1.-1.3. — Unit Configuration and

Switch Check

IMPORTANT: The field-supplied and installed switch

(or timeclock) MUST BE CLOSED to put unit in

Occupied mode. Unit WILL NOT START until this is

accomplished.

The microprocessor in unit control system is pro-

grammed by 2 switch assemblies located on processor

board (Fig. 1). The configuration header is factory set and

cannot be changed in the field. The DIP switch assembly

contains 8 microswitches that must be set in accordance

with the various options selected by the customer. All

DIP switches should be checked and set to proper posi-

tion for options selected prior to the quick test. See Con-

figuration of Header and DIP Switch Assembly section

on page 5 for factory switch settings. The DIP switch

functions and display codes are shown in Table 16.

3. Initialization mode begins (see Operating Information

section on page 34 for complete description of sequences

and display codes).

4. Run Quick Test. If the display button is pressed during

the initialization mode period, the unit will run its self-

diagnostic routine. When this is in effect, an 88 will ap-

pear in the display screen. Refer to Quick Test Program

section below, for instructions on completing the Quick

Test program.

Quick Test Program — Turn on power to unit.

2. Quick Test Steps 1.4.-2.3. — Thermistor and Set Point

Potentiometer Check

IMPORTANT: The field-supplied switch (or timeclock)

must be closed to put unit into the occupied mode.

In these steps, the microprocessor checks resistance val-

ues of all sensors and set point potentiometers to ensure

that they are functional, connected properly, and set with-

in proper range for unit configuration.

Nominal resistance values for all sensors range from

363,000 to 219 ohms in accordance with Table 19. Nor-

mal display code for good sensors and potentiometers

is 1. A display code of 0 indicates a faulty potentiometer,

thermistor or wiring. A 0 display also indicates that op-

tion is not being used.

The quick test program utilizes the 2-digit LED display (see

Fig. 6) on the set point board to show status of all input and

output signals to microprocessor. Display action and quick test

procedures are described below.

The quick test program is a 33-step program that provides a

means of checking all input and output signals of controls prior

to unit start-up. This check ensures that all control options,

thermistors, and control switches are in proper working order.

When unit control circuit is switched to Occupied mode, a

20 will appear on the display. Immediately press display button

once. An 88 will appear on the display and alarm light on

Table 17 shows thermistor and set point potentiometer

functions and quick test display codes.

Table 16 — Quick Test, Unit Configuration and Switch Check

QUICK

TEST

NORMAL

DESCRIPTION

Type Unit — Air-Cooled VAV

CONTROL SWITCH

Configuration Header

DISPLAY

STEP NO.

No. of Compressors

Configuration Header

DIP Switch No. 6 and 7

No. of Unloaders

(034,038,048-088)

(044, 104)

60-Hertz Power

Configuration Header

DIP Switch No. 2

0 — No Reset (Switch Off)

1 — Reset On (Switch On)

0 or 1

0 — No Economizer (Switch Off)

1 — Economizer On (Switch On)

DIP Switch No. 3

DIP Switch No. 4

DIP Switch No. 5

0 or 1

0 — No Warm-Up (Switch Off)

1 — Warm-Up Used (Switch On)

0 — Demand Limit Not Used

(Switch Off)

1 — Demand Limit Used

(Switch On)

0 or 1

0 — Enthalpy Switch Open

1 — Enthalpy Switch Closed

0 or 1

1.0.

1.1.

1.2.

1.3.

1 — Low-Pressure Switch Closed

No Circuit 1 Oil Pressure Switch

No Circuit 2 Oil Pressure Switch

Low-Pressure Switch 1

Low-Pressure Switch 2

None*

LEGEND

DIP — Dual, In-Line Package

EC — Enthalpy Control

VAV — Variable Air Volume

*Units are not equipped with oil pressure switches.

Table 17 — Quick Test, Thermistor and Potentiometer Check

QUICK

TEST

STEP NO.

NORMAL

DISPLAY

THERMISTOR OR

POTENTIOMETER*

DESCRIPTION

1 — Thermistor OK

Supply Air

1.4.

1.5.

1.6.

1.7.

0 — Thermistor Faulty

Thermistor (T1)

1 — Thermistor OK

0 — Thermistor Faulty

1 — Thermistor OK

0 — Thermistor Faulty

1 — Thermistor OK

0 — Thermistor Faulty

Return Air

Thermistor (T2)

Circuit 1 Condenser Thermistor

(T3)

Circuit 2 Condenser Thermistor

(T4)

1 — Thermistor or Potentiometer OK

0 — Thermistor or Potentiometer Faulty or

Option not used

Accessory Space Temperature Thermistor (T10)

or Accessory Reset Potentiometer (P7)

1.8.

1 — Potentiometer OK

Supply-Air Set Point

Potentiometer (P1)

Accessory Reset Limit

Potentiometer (P3)

Accessory Demand Limit

Potentiometer (P4)

1.9.

2.0.

2.1.

0 — Potentiometer Faulty

1 — Potentiometer OK

0 — Potentiometer Faulty or Option not used

1 — Potentiometer OK

0 — Potentiometer Faulty or Option not used

1 — Potentiometer OK

Minimum Position

Economizer

2.2.

2.3.

0 — Potentiometer Faulty or Option not used

Potentiometer (P5)

1 — Potentiometer OK

0 — Potentiometer Faulty or Option not used

Warm-Up Set Point

Potentiometer (P6)

*Potentiometer P2 is not listed since it is not part of the quick test. If on unit start-up a Code 83 is displayed, check potentiometer P2.

Table 18 — Quick Test, Output Relay Check

QUICK

NORMAL

DISPLAY

TEST

DESCRIPTION

RELAY NUMBER

STEP NO.

2.4.

2.5.

2.6.

2.7.

2.8.

2.9.

3.0.

3.1.

3.2.

3.3.

1 — Open Economizer or Open Relay if no Economizer

1 — Close Economizer or Close Relay if no Economizer

1 — Energize Fan Relay and Heat Relay

Energize Stage 1 Condenser Fan(s)

Energize Stage 2 Condenser Fan(s)

Energize Compressor 1†

K9* and K10

K11

K12

0 then 1 then 0

Energize Unloader 2; Not Used (044, 104)

Energize Unloader 1

0 then 1 then 0

Energize Compressor 2†

Not Used

LEGEND

CR — Control Relay

*K9 (fan relay) will remain on for duration of quick test.

†Compressor will be energized for 10 seconds. Zero indicates open CR; 1 indicates closed CR.

Table 19 — Sensor Resistance Values

enthalpy is good. As long as the outdoor-air enthalpy is accept-

able, no mechanical cooling will take place until the economiz-

er dampers are fully open. The rest of the steps and the opera-

tional sequence vary due to the number of compressors and un-

loaders. Refer to Operating Sequence section on page 35 for

the unit stages of operation.

CODES 20 THROUGH 30 AND 88, OPERATIONAL STA-

TUS — These codes indicate special operational modes, such

as initialization, morning warm-up, temperature reset, demand

limit, or an internal failure of the board. Codes 23-25 and

27-29 are not used on these units.

Initialization — When the control is turned on, the display

shows a 20 for approximately 2 minutes to indicate that the

control is in the initialization mode. During this time, the econ-

omizer dampers open and close to determine the resistance

range of the economizer position potentiometer (P2) for full

economizer operation. The processor loads the necessary con-

stants for proper unit operation and checks the thermistors and

other potentiometers for their values and validity. After the ini-

tialization period, the display screen goes blank until the dis-

play button is pressed. If the display button is pressed during

the 2-minute initialization period, the control goes into the

Quick Test mode.

Temperature Reset — If the unit is equipped with the accesso-

ry temperature reset package, and DIP switch 2 is in the ON

position, the unit will reset the supply-air temperature to a cal-

culated value when necessary. When this condition is in effect,

a 21 will appear in the display.

TEMP RESISTANCE TEMP RESISTANCE TEMP RESISTANCE

(F)

(Ohms)

(F)

(Ohms)

(F)

(Ohms)

–60

–55

–50

–45

–40

–35

–30

–25

–20

–15

–10

–5

362,640

297,140

245,245

202,841

168,250

139,960

116,820

98,420

82,665

69,685

58,915

50,284

42,765

36,475

31,216

26,786

23,164

19,978

17,276

14,980

13,085

11,396

9,950

8,709

7,642

6,749

5,944

5,249

4,644

4,134

3,671

3,265

2,913

2,600

2,336

2,092

1,879

1,689

1,527

1,377

1,244

1,126

150

155

160

165

170

175

180

185

190

195

200

205

210

215

220

225

230

235

240

1,020

929

844

768

699

640

585

535

490

449

414

380

350

323

299

276

255

236

219

100

105

110

115

120

125

130

135

140

145

3. Quick Test Steps 2.4.-3.3. — Output Relay Check

These quick test steps allow microprocessor to check out-

put signals from relay boards in unit control system. In

addition, operation of all the condenser fans, compres-

sors, and economizer (if equipped) are checked at each

step.

Normal display for Steps 2.4. through 2.8. is 1. In Steps

2.9. through 3.2., each compressor and unloader is started

and allowed to run for approximately 10 seconds. At

startup, a 0 will appear on the display followed by a

1 (Steps 2.9. and 3.2.) in a few seconds. Steps 3.0. and

3.1. will always be 0 since there are unloaders, and Step

3.3. will always be zero since it is not used.

At end of the 10-second time period, a 0 will return to the

display board indicating that test step has been success-

fully completed (Steps 2.9. and 3.2.). The 1 indicates that

was tested.

Fan and compressor operating sequence for quick test

Steps 2.4. through 3.3. are shown in Table 18.

Demand Limit — If the unit is equipped with the accessory

demand limit control module or the field-supplied, single-step

demand limit potentiometer, and DIP switch 5 is in the ON

position, the unit will limit the capacity stages to a predeter-

mined value. When this condition is in effect, a 22 will appear

in the display.

Morning Warm-Up — If the morning warm-up heat routine is

enabled using DIP switch 4, and conditions of the occupied

space warrant, the unit will begin the morning warm-up rou-

tine. When this condition is in effect, a 26 will appear in the

display.

If the quick test steps do not operate as described above, a

defect exists in one or more of the following: relay being test-

ed, electronic control, or unit wiring. Determine problem and

correct.

Internal Failure — If the unit detects an internal fault (such as

a time measurement failure), or detects an incorrect voltage on

an input channel, a 30 will be displayed, and the unit will shut

down.

Quick Test — If the display button is pressed during the ini-

tialization period of the processor, the unit will run its self-diag-

nostic routine. When this is in effect, an 88 will appear in the

display screen.

CODES 51 THROUGH 87, DIAGNOSTIC INFORMATION

— These codes indicate diagnostic information when there is a

unit problem such as a faulty thermistor, potentiometer, or

compressor fault. Refer to Diagnostic Codes section on

page 45 for more details. Codes 53, 54, 57, 58, 61, 62, 65-69,

73, 74, and 77-80 are not used on these units.

Under normal operation, only the stage number is displayed

when the display button is pressed. If a status or overload code

is displayed, the display will rotate every 2 seconds and will

display up to 3 codes. Overload information takes priority over

all other codes. The codes are stored in the microprocessor as

long as the board remains energized.

OPERATING INFORMATION

Digital Display — The VAV control system uses a 2-digit

LED display located on the display board to display operation-

al information and diagnostic codes.

CODES 0 THROUGH 8, CAPACITY STEPS — These codes

indicate the number of cooling stages active at the time the dis-

play button is pressed. The highest code indicated on the dis-

play will be 6 for the 034,038 and 048-088 units, 4 for the 044

units, and 8 for the 104 units.

Capacity steps are directly related to pin terminal connector

J6 output. At step zero, the unit has no mechanical cooling on,

and the economizer may or may not be operating (depending

on the outdoor air conditions). Once a cooling load is detected

(T1 thermistor reads above the supply-air set point), the econo-

mizer will begin modulating to meet the load if the outdoor

Compressors, unloaders, and condenser fans will be cycled

to maintain a supply-air temperature 2° F below the potentiom-

eter P1 set point once the mechanical cooling stages begin.

Each unit’s cycling is slightly different, and is based on the

number of compressors and unloaders. The operational loading

sequence of compressors is as follows:

During the start-up of the lead compressor for each circuit,

the low-pressure switch will be bypassed for 120 seconds to

prevent nuisance trips of the low-pressure switch. After start-

up, a low-pressure trip will be ignored for 30 seconds by the

processor.

SIZE 034,038 AND 048-088 UNITS — These units have 2

compressors and 2 unloaders on compressor 1. See Fig. 42 and

43 for compressor and condenser-fan motor locations. The

operating sequence is as follows:

Stage 1 Relays K1, K2, and K3 are energized. Compressor

no. 1 starts with both unloaders energized. Compres-

sor no. 1 runs at ¹/₃capacity. The crankcase heater for

this compressor has been deenergized, and the first

stage of condenser fans have been energized. Out-

door (condenser) fan motor no. 1 (OFM1) has started

on all units.

Operating Sequence — The sequence presented be-

low assumes that the unit is equipped with heat for morning

warm-up and an economizer. If these items are not enabled

with the appropriate DIP switches, the processor bypasses

these subroutines. This sequence is also based on an EPROM

(erasable, programmable, read-only memory) processor chip

with the identification ‘HT204485-1-XX,’ where ‘XX’ is re-

placed by a 2-digit number representing the current software

version. See Fig. 1 for EPROM chip location.

When power is applied to the occupied mode relay (OMR)

through the closure of either a field-installed timeclock or a

field-installed switch in the occupied space, the unit will begin

its initialization mode.

A 20 will appear in the display screen, and the initialization

period will last approximately 2 minutes. During this time, the

economizer dampers open and close to determine the resis-

tance range for full economizer operation of the economizer

position potentiometer (P2). The processor loads the necessary

constants for unit operation, and also checks the thermistors

and other potentiometers for their values and validity. After the

initialization period, the screen goes blank until the display but-

ton is pressed.

Stage 2 Relays K1 and K3 are energized. Compressor no. 1 is

running with unloader 1 (U1) energized. The com-

pressor is now operating at ²/₃capacity.

Stage 3 Relay K1 is energized. Compressor no. 1 is fully

loaded.

Use caution during this time (after initialization when the

screen is blank), because the unit supply and return fans

could start at any time. Personal injury could result from

contact with rotating fans.

Stage 4 Relays K1, K2, K3, and K5 are energized. Compres-

sor no. 1 is running at /₃capacity, and compressor

Once the initialization period is complete, the supply fan be-

gins operation. While the fan is operating, the economizer

dampers are closed and return air from the building is being

circulated. After 2 minutes, the processor checks the resistance

value of thermistor T2. If T2 temperature sensed is 5° F or

more below the set point of the morning warm-up potentiome-

ter (P6), the unit will begin the morning warm-up routine, and

a 26 will be displayed.

no. 2 is running at full capacity. The crankcase heater

for compressor no. 2 has been deenergized.

Stage 5 Relays K1, K3, and K5 are energized. Compressor

no. 1 is running at ²/₃capacity, and compressor no. 2

is running at full capacity.

Stage 6 Relays K1 and K5 are energized. Both compressors

are running fully loaded.

Size 034 and 038 units have 2 condenser fans, one of which

is controlled by the microprocessor. The OFM1 is energized

with compressor no. 1. The OFM2 is controlled by the proces-

sor and is cycled based on input from circuit thermistor T3 or

T4.

Size 048 units have one fan that can be controlled by the

processor. The other 2 are controlled by the compressors. The

OFM1 is energized by compressor no. 1, and OFM3 is ener-

gized by compressor no. 2. The OFM2 is cycled by the proces-

sor based on input from either circuit (thermistors T3 and T4).

Unit heat will be energized through the heat interlock relay

(HIR), and all of the occupied space air terminals will open.

The unit will continue heating the space until the return-air

temperature is within 2° F of set point. The unit will then shut

off the heat and continue to circulate air. The unit will cycle in

and out of the Heating mode until the return-air temperature

reaches the morning warm-up set point (P6). Once morning

warm-up has been terminated, the unit cannot return to morn-

ing warm-up until the unit is powered down and restarted. This

action signals a return to the Occupied mode.

NOTE: Occupied heat is NOT AVAILABLE on these units.

On size 054,064 units, the first 2 condenser fans energize

with the compressors; compressor no. 1 controls OFM1, and

compressor no. 2 controls OFM2. The OFM3 and OFM4 are

staged by the microprocessor based on the condensing temper-

ature input from thermistor T3 or T4.

On size 074-078 units, the first 3 condenser fans energize

with the compressors; compressor no. 1 controls OFM1, and

compressor no. 2 controls OFM2 and OFM3. The OFM4 and

OFM5 are staged by the microprocessor based on condensing

temperature input from either circuit’s T3 or T4 thermistor.

On Size 088 units, the first 4 condenser fans energize with

the compressors; compressor no. 1 controls OFM1 and OFM3,

and compressor no. 2 controls OFM2 and OFM4. The OFM5

and OFM6 are staged by the microprocessor based on

condensing temperature input from either circuit’s T3 or T4

thermistor.

Once out of the morning warm-up routine, the unit will be-

gin its cooling routine based on the supply-air set point (P1). At

step zero, the unit has no mechanical cooling on, and the econ-

omizer may or may not be operational. The economizer will

move to the minimum position determined by potentiometer

P5 if no cooling load is detected. Once a cooling load is detect-

ed by thermistor T1 sensing a temperature higher than the cool-

ing demand set point (P1), the economizer will begin modulat-

ing to meet the load if the outdoor enthalpy is good. The pro-

cessor will attempt to maintain a supply-air temperature of P1

± 2° F by modulating the economizer dampers.

No mechanical cooling will take place until the economizer

dampers are fully open (if the outdoor-air enthalpy permits). If

the economizer is unable to meet the cooling demand, then me-

chanical cooling is used in conjunction with the economizer. If

the economizer is unable to meet the load due to unacceptable

outdoor-air enthalpy, the dampers will return to the minimum

position as determined by P5.

SIZE 044 UNITS — These units have 2 compressors and 1

unloader on compressor no. 1. See Fig. 42 for compressor and

condenser fan motor locations. The unit operating sequence is

as follows:

Stage 5 Relays K1, K3, K5, and K5 are energized. Compres-

sor no. 1 runs at /₃capacity and compressors no. 2

and no. 4 are running at full capacity. The crankcase

heater on compressor no. 4 is deenergized. Fans

OFM1, OFM2, OFM3, and OFM4 are operating.

Stage 1 Relays K1 and K3 are energized. Compressor no. 1

starts with the unloader energized. Compressor no. 1

Stage 6 Relays K1, K5, and K6 are energized. Compressors

no. 1, no. 2, and no. 4 are running fully loaded.

is running at /₂capacity. The crankcase heater on

compressor no. 1 has been deenergized, and the first

stage condenser fan has been energized. Outdoor

(condenser) fan motor no. 1 (OFM1) has started.

Stage 7 Relays K1, K2, K3, K5, and K6 are energized. Com-

pressor no. 1 runs at ²/₃capacity and compressors no.

2, no. 3, and no. 4 are running at full capacity. Fans

OFM1, OFM2, OFM3, and OFM4 are operating.

Crankcase heater for compressor no. 3 is deener-

gized.

Stage 8 Relays K1, K2, K5, and K6 are energized. Compres-

sors no. 1, no. 2, no. 3, and no. 4 are running fully

loaded.

On size 104 units, the first 4 condenser fans energize with

the compressors; circuit no. 1 compressors control OFM1 and

OFM3, and circuit no. 2 compressors control OFM2 and

OFM4. The OFM5 and OFM6 are staged by the microproces-

sor based on condensing temperature input from either circuit’s

T3 or T4 thermistor.

Stage 2 Relay K1 is energized. Compressor no. 1 is fully

loaded.

Stage 3 Relays K1, K3, and K5 are energized. Compressor

no. 1 is running at ¹/₂capacity, and compressor no. 2

is running at full capacity. The crankcase heater for

compressor no. 2 is deenergized. The second stage

condenser fan has been energized. Both OFM1 and

OFM3 are operating.

Stage 4 Relays K1 and K5 are energized. Both compressors

are running fully loaded.

Size 044 units have one fan that can be controlled by the

processor. The other 2 are controlled by the compressors. The

OFM1 is energized by compressor no. 1, and OFM3 is ener-

gized by compressor no. 2. The OFM2 is cycled by the proces-

sor based on input from either circuit (thermistors T3 and T4).

SIZE 104 UNITS — These units have 4 compressors and 1

unloader on compressor no. 1. See Fig. 43 for compressor and

condenser fan motor locations. The unit operating sequence is

as follows:

Stage 1 Relays K1 and K3 are energized. Compressor no. 1

starts with unloader energized. Compressor no. 1 runs

at ²/₃capacity. The crankcase heater for this compres-

sor has been deenergized, and first stage of condenser

fans has been energized. Outdoor (condenser) fan

motor no. 1 (OFM1) and outdoor fan motor no. 3

(OFM3) have started.

Head Pressure Control — All units have as standard a

basic head pressure control function which allows the units to

operate in cooling down to 45 F. If cooling is required at out-

door ambient temperatures lower than 45 F, refer to accessory

head pressure control literature for details.

Head pressure control is handled by the processor. The pro-

cessor attempts to maintain the head pressure by cycling the

condenser-fan motors. No condenser fans will be running with-

out a call for mechanical cooling. Thermistors T3 and T4 pro-

vide the condensing temperature information to the processor.

These VAV rooftop units have dual refrigeration circuits, and

the higher circuit temperature will govern unit operation. If the

condensing temperature is above 133 F (236 psig), a condenser

fan stage will be added. If the condensing temperature is 78 F

(142 psig) or less, the number of condenser fans operating will

be decreased. After each fan stage, the processor will wait one

minute for the head pressures to stabilize before changing

again, unless thermistor T3 or T4 senses a temperature greater

than 125 F (278 psig), in which case all condenser fans are

started.

Stage 2 Relay K1 is energized. Compressor no. 1 is fully

loaded.

Stage 3 Relays K1, K3, and K5 are energized. Compressor

no. 1 runs at ²/₃capacity and compressor no. 2 is run-

ning at full capacity. The crankcase heater for com-

pressor no. 2 is deenergized. The first stage of

condenser fans on circuit 2 has been energized. Fans

OFM1, OFM2, OFM3, and OFM4 are operating.

During start-up, if the outdoor ambient is above 70 F (as

sensed by thermistor T3 or T4), the first-stage, processor-

controlled fans are turned on to prevent excessive discharge

pressures.

Stage 4 Relays K1 and K5 are energized. Both compressors

no. 1 and no. 2 are running fully loaded.

044 AND 048 UNITS

034 AND 038 UNITS

LEGEND

OFM

— Outdoor (Condenser) Fan Motor

Fig. 42 — Component Arrangement, 034-048 Units

054, 064 UNITS

054-088 UNITS

074, 078 UNITS

088, 104 UNITS

104 UNITS

Fig. 43 — Component Arrangement, 054-104 Units

As the economizer actuator opens past 17% open, auxiliary

switch DMS1 closes, energizing fan contactor PEC1. Fan mo-

tor no. 1 starts and runs.

Capacity of fan no. 1 is controlled by the position of the out-

let damper. As building pressure increases above set point,

the DPS will close its contact and drive the power exhaust

damper motor (PEDM) open until set point is achieved. DPS

then opens its control contacts and PEDM maintains current

position.

When space demand moves PEDM to 90% of full-open po-

sition, auxiliary switch PEDMS closes, energizing fan contac-

tor PEC2. Fan motor no. 2 starts and runs. Increased exhaust

airflow will lower space pressure, causing DPS to drive PEDM

back towards its closed position, until the set point is achieved.

If space pressure decreases until PEDM position is reduced

to 10% of open position, PEDMS will open, deenergizing fan

contactor PEC2 and shutting off fan no. 2.

Supply Fan Control with IGV — In most VAV units,

the supply fan static pressure is controlled by inlet guide vanes.

The inlet guide vanes operate independently from the micro-

processor. The supply static pressure is controlled by a differ-

ential pressure switch.

For example, assume that set point on supply fan differen-

tial switch is 1.9 in. wg. If pressure in supply duct goes above

1.9 in. wg, switch will make to the normally open contact and

energize inlet guide vane motor to drive inlet guide vanes to a

more closed position, thus reducing airflow and lowering duct

pressure. Once set point pressure is reached, switch will open

and deenergize inlet guide vane motor. If pressure in supply

duct is below 1.9 in. wg, the switch will make to the normally

closed contact and energize inlet guide vane motor to drive in-

let guide vane to a more open position; increasing airflow and

raising duct pressure. Once again, once desired pressure has

been reached, switch will open and deenergize inlet guide vane

motor. How far above or below the set point setting the switch

goes before energizing depends on setting of null span (null

span is pressure change that can be made without contacts

opening or closing). If null span is at maximum position, pres-

sure will vary from 0.17 in. wg to 0.31 in. wg depending on set

point (if set point is at minimum setting, null span will be

0.17 in. wg, while if it is at maximum position, the null span

will be 0.31 in. wg) before switch acts. If null span is adjusted

to a minimum setting, duct pressure will vary from 0.06 in. wg

to 0.11 in. wg (again depending on switch set point) before

switch acts. Setting null span to minimum position will result

in a smaller pressure fluctuation than if it is set at maximum

position.

High Capacity Modulating Power Exhaust

(48FM and 50 FM,FS Units) — The high-capacity

modulating power exhaust assembly consists of two parallel

and independent belt-drive large diameter forward curve fans.

The fans, motors, and drives are located in a cabinet extension

(not over the return air opening of the unit), in a plenum be-

neath the outside air intake plenum. The fans discharge hori-

zontally out the back of the unit through individual barometric

backdraft dampers with hoods. Operation is interlocked with

economizer operation. Space pressure is monitored by a

factory-installed differential pressure transducer. See Fig. 48

for component locations and sheet metal details.

The high-capacity modulating power exhaust is also avail-

able on horizontal 50FS units. Return duct opening is located

on the left-hand side of the unit; exhaust air exits the unit out

the back.

Control of the high-capacity modulating power exhaust sys-

tem is accomplished via a combination modulated capacity

fan/staged fan. Modulation is provided by a variable frequency

drive controlling the direct output to fan no. 1 and controlling

the ON/OFF status of fan no. 2.

Fan no. 1 is equipped with a Variable Frequency Drive,

matched to the motor size. VFD output is determined by the

VFD’s internal PID logic in response to actual space pressure

as monitored by the Building Pressure (BP) transducer. Set

point for BP control is established at the PE VFD. Available set

point range is –0.50 to +0.50 in. wg. Building Pressure is

sensed by a pick-up (field-supplied and -installed) located in

the occupied space and connected to the BP transducer by

¹/₄-in. tubing (field-supplied and -installed).

Supply Fan Control with VFD — When equipped

with the VFD option, the supply fan static pressure is con-

trolled by modulating the fan wheel speed. The VFD operates

independently from the microprocessor. A duct pressure trans-

ducer monitors duct static pressure. The transducer output (4 to

20 mA) is directed into the VFD. The VFD adjusts supply fan

motor speed (which changes wheel speed) as measured duct

pressure varies from set point as established at the VFD. The

VFD will modulate fan speed until the duct pressure set point is

achieved.

NOTE: The VFD will always provide the proper phase

sequence to the supply fan motor. This motor will operate in

proper rotation regardless of the phase sequence to the unit. If,

upon start-up, the outdoor fans operate backwards but the

indoor fan operates in the correct direction, reverse any two

leads to the main terminal block. All fans will then operate in

the correct direction.

Operation of the modulating power exhaust is a combina-

tion modulating/staged control, with fan no. 1 providing modu-

lating control from 0 to 50% of total exhaust capability, and fan

no. 2 being staged On/Off (for a step of 50% of total exhaust

capability) according to VFD output level on fan no. 1.

As the economizer actuator opens past 17% open, auxiliary

PEC1. Fan motor no. 1 starts and runs.

Capacity of fan no. 1 is controlled by the output level from

the BP VFD. As building pressure increases above set point,

the VFD logic will increase the output level to fan no. 1 until

set point is reachieved.

When space demand moves PE VFD output to 100%

(60 Hz), VFD internal relay closes, energizing fan contactor

PEC2. Fan motor no. 2 starts and runs. Increased exhaust air-

flow will lower space pressure, causing PE VFD to reduce its

output to fan no. 1 until set point is reachieved.

Modulating Power Exhaust (48FK,JK and

50FK,JK Units Option or Accessory) — The pow-

er exhaust assembly consists of two parallel and independent

belt-drive forward curve fans. The fans, motors, and drives are

located over the return air opening of the unit, in a plenum be-

neath the outside air intake plenum. The fans discharge air hor-

izontally out the back of the unit through individual barometric

backdraft dampers with hoods. (See Fig. 44 and 45.) Operation

is interlocked with economizer operation. Sheet metal installa-

tion is shown in Fig. 46 and 47.

Fan no. 1 is equipped with a variable position discharge

damper located in the outlet of the fan housing. This damper is

controlled by an actuator (PEDM), based on signals from the

building pressure differential pressure switch (DPS). Available

range on the DPS is -0.50 to +0.50 in. wg, adjustable. Building

pressure is sensed by a pick-up (field-supplied and -installed)

located in the occupied space.

If space pressure decreases until PE VFD output is reduced

to 25% of maximum output (15 Hz), VFD internal relay will

open, deenergizing fan contactor PEC2 and shutting off fan

no. 2.

Operation of the modulating power exhaust is a combina-

tion modulating/staged control, with fan no. 1 providing modu-

lating control from 0 to 50% of total exhaust capability, and fan

no. 2 being staged On/Off (for a step of 50% of total exhaust

capability) according to damper position on fan no. 1.

Unit Staging — Compressor loading and unloading se-

quences are shown in Table 20.

Fig. 44 — Modulating Power Exhaust Component Locations; Sizes 034-048

Fig. 46 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 034-048

Fig. 47 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 054-104

PE VFD

ACCESS DOOR

AUXILIARY

CONTROL BOX

LARGE ECONOMIZER

HOOD LOCATION

EXHAUST

AIR

POWER EXHAUST

ACCESS DOOR

SMALL ECONOMIZER

HOOD LOCATION

Fig. 48 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; 48FM and 50FM,FS Units

Table 20 — Compressor Loading and Unloading Sequences

SIZE 034 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

OFF

SIZE 038 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

OFF

Table 20 — Compressor Loading and Unloading Sequences (cont)

SIZE 044 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Percent

Cylinders

Capacity

Comp 1

Comp 2

OFF

100

OFF

SIZE 048 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

OFF

SIZE 054 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

SIZE 064 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

OFF

SIZE 074, 078 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

OFF

Table 20 — Compressor Loading and Unloading Sequences (cont)

SIZE 088 UNITS

COOLING

STAGE

Lead Circuit

Unloader

Lag Circuit

Active

Cylinders

Percent

Capacity

Unloader

Comp 1

Comp 2

OFF

100

OFF

SIZE 104 UNITS

Lag Circuit

COOLING

STAGE

Lead Circuit

Unloader

Active

Cylinders

Percent

Capacity

Comp 1

Comp 3

Comp 2

Comp 4

OFF

100

OFF

•

Blown fuse in the control power feed.

Open control circuit fuse.

TROUBLESHOOTING

By using the display module, actual operating conditions of

the unit are displayed while it is running. The Quick Test func-

tion allows proper operation of compressors, compressor un-

loaders, fans, and other components to be checked while unit is

stopped. If an operating fault is detected, an alarm is generated

and an alarm code(s) is displayed. For checking specific items,

see Table 21.

Operation of the unit blocked by the demand limit

function.

•

Unit supply-air temperature (T1) thermistor failure.

Supply-air fan is not operating.

High duct static pressure.

Single Circuit Stoppage — If a single circuit stops,

there are several potential causes:

Checking Display Codes — To view the digital dis-

play codes, press the button located to the right of the LED dis-

play/set point board in the control box. See Table 22 for Opera-

tional Status Codes. See Table 23 for Diagnostic Codes.

•

Open contacts in the compressor high-pressure switch.

Low refrigerant pressure.

Thermistor failure.

Unit supply-air temperature thermistor (T1) failure.

Compressor circuit breaker trip.

Operation of the circuit blocked by the demand limit

function.

Complete Unit Stoppage — If the unit is off, there are

several conditions that can cause this situation to occur:

•

Remote ON/OFF circuit in Unoccupied mode.

Unit ON/OFF switch moved to OFF position.

Programmed schedule at the timeclock.

General power failure.

Table 21 — Controls Troubleshooting

SYMPTOM(S)

PROBABLE CAUSE(S)

SOLUTION(S)

Controls do not seem

to be operating.

Remote on-off function may be

keeping controls off.

Check status.

1. Circuit breaker open.

1. Find cause and reset circuit breaker.

2. Find cause and reset.

1. Find cause and reset circuit breaker.

2. Correct operation.

Evaporator fan does not run.

Compressor does not run.

2. Inverter overload (if equipped).

1. Circuit breaker is open.

2. There is no demand for cooling.

3. The control is locking out cooling operation.

3. Check rotating display for alarm codes. Resolve

alarm cause and reset control by changing to

standby and back to run mode.

4. Demand Limit in effect.

Circuit breaker is open.

4. Check Demand Limit Settings.

Condenser fans do not

turn on.

Cooling demand exists and

economizer modulates, but

compression is not operating.

Find cause and reset circuit breaker

Correct operation.

Compression cannot be initiated

until economizer damper is 90% open.

Table 22 — Operation Status Codes

CODES 51, 52, 55, 56: COMPRESSOR FAILURE — If con-

trol relay (CR) opens while compressor should be operating,

compressor will stop and microprocessor will energize alarm

light and display a code of 51 , 52 , 55 or 56 (depending on

compressor) when display button is pushed. The compressor

will be locked off; to reset, the ON-OFF switch must be turned

to OFF and then to ON position.

If lead compressor in a refrigerant circuit is shut down, the

other compressor in that circuit will also be shut down and

locked off. Only the error code for the lead compressor will be

displayed.

CODE

MEANING

0 cooling stages active

1 cooling stage active

2 cooling stages active

3 cooling stages active

4 cooling stages active

5 cooling stages active

6 cooling stages active

7 cooling stages active

8 cooling stages active

Code 51 is for compressor 1, and Code 55 is for compressor

2. Codes 52 and 56 are used for compressors 3 and 4, respec-

tively, on size 104 units.

Initialization mode (Allow 2 minutes

The microprocessor has also been programmed to indicate a

compressor failure if CR switch is closed when compressor is

not supposed to be on.

for initialization. To initiate Quick Test,

press the Display button while 20 is displayed.)

Temperature Reset in effect

Demand Limit in effect

If a failure occurs, the following are possible causes:

High-Pressure Switch Open — The high-pressure switch for

each compressor is wired in series with 24-v power that ener-

gizes CR. If high-pressure switch opens during operation, CR

will stop compressor and this will be detected by microproces-

sor through the feedback contacts.

Morning Warm-Up in effect

Internal failure detected

Self-diagnostic mode in effect

Restart Procedure — Before attempting to restart the

machine, check the display for alarm codes to determine the

cause of the shutdown. If the unit, circuit, or compressor stops

more than once as a result of a safety device, determine and

correct the cause before attempting to start the unit again.

After the cause of the shutdown has been corrected, unit

restart may be automatic or manual depending upon the fault.

Internal Thermostat — The internal thermostat in each 06D

compressor is also wired in series with 24-v power that ener-

gizes CR. If thermostat fails or switch opens during operation

of compressor, compressor will shut down and failure is detect-

ed through feedback contacts (size 034 and 038 only).

CR Failure — If CR fails with large relay either open or

closed, microprocessor will detect this, lock compressor off,

and indicate an error.

Diagnostic Codes — Diagnostic codes are warnings of

abnormal or fault conditions, and may cause either one circuit

or the whole unit to shut down. They are assigned code num-

bers as described below.

Relay Board Failure — If small 24-v relay on the relay board

fails, microprocessor will detect this through feedback contacts

and indicate an error.

Processor Board Failure — If hardware that monitors feed-

back switch fails and processor board fails to energize the relay

board relay to ON position, an error may be indicated.

Table 23 contains a description of each diagnostic code er-

ror and possible cause. Manual reset is accomplished by mov-

ing the ON/OFF Switch to the OFF position, then back to ON.

The control does not detect compressor circuit breaker

failures.

Wiring Problem — A wiring error or a loose wire may cause

the feedback circuit to be broken.

The 2-digit LED display is used to display the diagnostic

codes and the alarm light (located next to display) is energized

whenever a diagnostic code is tripped. When a problem is

suspected, always check the display first for diagnostic

information.

NOTE: Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80

are not used on these units.

IMPORTANT: The microprocessor memory and the dis-

play will be cleared if the power to the microprocessor is

shut off. DO NOT attempt to bypass, short, or modify

the control circuit or electronic boards in any way to cor-

rect a problem. This could result in a hazardous operat-

ing condition.

Table 23 — Diagnostic Codes

ACTION TAKEN

BY CONTROL

RESET

DISPLAY

DESCRIPTION OF FAILURE

Compressor 1 failure

Compressor 2 failure

Compressor 3 failure

Compressor 4 failure

PROBABLE CAUSE

METHOD

Circuit 1 shut off

Manual

High-pressure switch or high dis-

charge gas thermostat switch

trip, compressor ground current

>2.5 amp or compressor board

relay on when it is not supposed

to be on. Wiring error between

electronic control and compres-

sor protection module.

Circuit 2 shut off

Compressor 3 shut off

Compressor 4 shut off

Loss-of-charge circuit 1

Loss-of-charge circuit 2

Circuit 1 shut off

Circuit 2 shut off

Manual

This indicates either a low refrig-

erant charge, or a loss-of-charge

switch failure.

Low oil pressure circuit 1

Low oil pressure circuit 2

Circuit 1 shut off

Circuit 2 shut off

Manual

Not used; Check jumper on pro-

cessor board.

Illegal unit configuration

Unit will not start

Manual

Configuration error (see Note 1).

Supply-air thermistor failure

Return-air thermistor failure

Circuit 1 saturated condensing thermistor

Circuit 2 saturated condensing thermistor

Reset temperature thermistor failure

Unit shut off

Auto.

Thermistor or resistor failure, wir-

ing error, or thermistor or resistor

not connected to the processor

board.

Use default value

Unit shut off

Stop reset

Auto.

Supply-air set point potentiometer failure

Economizer potentiometer failure

Use default value

Close economizer

Stop reset

Stop demand limit

Close economizer

Use default value

Auto.

Potentiometer improperly con-

nected, potentiometer setting out

of range, potentiometer failure or

wiring error.

Reset limit set point potentiometer failure

Demand limit potentiometer failure

Minimum economizer potentiometer failure

Warm-up set point potentiometer failure

NOTES:

1. Illegal unit configuration caused by missing programmable header or both unloader DIP switches on.

2. All auto. reset failures that cause the unit to stop will restart when the error has been corrected.

3. All manual reset errors must be reset by turning the control switch off and then back on.

4. Valid resistance range for the thermistors is 363,000 to 585 ohms.

5. Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80 are not used on these units.

CODES 59 AND 60: LOW-PRESSURE SWITCH — These

codes are used to indicate a low-pressure switch failure.

been corrected. If a failure occurs, the following are possible

causes:

The processor monitors the low-pressure switch. If the

switch opens, either by low refrigerant charge, circuit failure,

or wiring error, the circuit is locked off. Code 59 indicates a

failure of the lead circuit, and as a result, that circuit will be

shut down. Code 60 indicates a failure of the lag circuit, and as

a result, that circuit will be shut down. These codes will only be

displayed when the display button is pressed. To reset the cir-

cuit, the ON-OFF switch must be turned to OFF, then ON

position.

CODES 63 AND 64: OIL PRESSURE SWITCH — These

codes are used to indicate an oil pressure switch failure. Since

the units do not have oil pressure switches, these codes are not

used. The terminals on the processor board must be jumpered

together or an error will occur. If these errors occur, check

jumper between J2-1 and J2-2 for a code 63, or between J2-3

and J2-4 for a code 64 to be sure jumper is properly connected.

To reset the circuit, the ON-OFF switch must be turned to OFF

and then to ON position.

CODE 70: ILLEGAL UNIT CONFIGURATION — If the

unit configuration header is not installed and properly config-

ured, and/or if DIP switches are not properly set, unit will not

start, and an error code of 70 will be indicated on display board

when display button is pushed. Check the header and DIP

switch settings.

CODES 71 TO 76: THERMISTOR/RESISTOR FAILURE —

If measured temperature of a thermistor is less than –60 F

(363,000 ohms) or greater than 180 F (585 ohms), the appro-

priate sensor error code (Table 23) will be displayed when

the display button is pushed. The unit will be shut down.

Thermistor failures will automatically reset once the error has

Thermistor or Resistor Failure — A shorted or open ther-

mistor or resistor will cause the failure.

Wiring Failure — If a wiring error exists that causes a shorted

or open circuit, this will cause a failure.

Processor Board Failure — If circuitry on processor board

fails, this could cause an error.

The codes are designated as follows:

Code 71 Supply-Air Thermistor Failure

Code 72 Return-Air Thermistor Failure

Code 73 Not used

Code 74 Not used

Code 75 Circuit 1 Saturated Condensing Thermistor

Code 76 Circuit 2 Saturated Condensing Thermistor

CODE 81: RESET THERMISTOR OR POTENTIOMETER

FAILURE — This is a unique code since the reset temperature

potentiometer (P7) is in series with the space temperature ther-

mistor (T10). If either one of these components fail, reset will

be terminated. This error will automatically reset once the situ-

ation is corrected. If an error is detected, the most probable

cause is one of the following:

•

Thermistor Failure — A shorted or open thermistor will

cause the failure.

Potentiometer Failure — If the potentiometer is outside

of the valid range (40 to 90 F), a failure will result.

Wiring Problem — If the circuit is open, a failure will be

detected.

Processor Board Failure — If the processor board fails

(hardware), an alarm will be detected.

CODE 82: SUPPLY-AIR TEMPERATURE SET POINT

POTENTIOMETER FAILURE — If supply-air set point

potentiometer (P1 — located on display board) fails, control

will use a default value. A failure will cause an error code of

82 to be displayed on display board when display button is

pushed; alarm light will also be energized. A failure is deter-

mined by establishing a range of –22 F to 70 F as a valid range.

Anything outside this range will be treated as a failure. If set-

ting is outside the –22 F to 70 F range, alarm light will be ener-

gized and an error code of 82 will be displayed when display

button is pushed; the control will use a set point of 70 F. If set

point is between –22 F and 45 F, control will use a set point of

45 F and no error code will be indicated. If potentiometer

returns to normal, control will automatically reset.

CODE 85: DEMAND LIMIT POTENTIOMETER (P4)

FAILURE — Used only if demand limit is being used. If

demand limit is used, DIP switch 5 must be in the ON position.

Two types of demand limit are available: a field-supplied

and installed single-step control consisting of a 10 Kohm,

3-wire linear potentiometer and an accessory 2-step control.

The single-step control has a single potentiometer while 2-step

control has 2 potentiometers (mounted on the demand limit

board, see Fig. 28).

For both types of demand limit, the control uses only 80%

of the total potentiometer resistance. If resistance of potentiom-

eter is less than 10% or greater than 90%, alarm light will be

energized, a diagnostic code of 85 will be displayed when the

display button is pushed, and demand limit will be terminated.

If a failure occurs, it is probably due to one of the following:

Potentiometer Failure — If a potentiometer is shorted or open,

a failure will occur.

Incorrect Potentiometer Setting — A potentiometer turned

fully clockwise or counterclockwise will put potentiometer out

of range resulting in an error.

Faulty Wiring — If wiring between the potentiometer and the

processor board is incorrect, an error will occur.

DIP Switch 5 — If DIP switch 5 is in the ON position and po-

tentiometer is not installed, an error will occur.

CODE 86: MINIMUM POSITION ECONOMIZER POTEN-

TIOMETER FAILURE — If potentiometer P5 (on accessory

board) setting is less than 0% or greater than 100%, alarm light

will be energized, a code of 86 will be displayed when display

button is pushed and economizer outdoor air dampers will

move to the fully closed position.

The potentiometer full-scale resistance is 10 Kohm, but

when installed in parallel with the other 2 potentiometers on

the accessory board, measured resistance will be 3.3 Kohm.

This failure will automatically reset when potentiometer re-

turns to normal.

If a failure occurs, one of the following is the probable

cause:

DIP Switch 3 — If this switch is in the ON position and the

accessory board is not installed (accessory board is standard on

these units, so it should always be on the unit).

Incorrect Potentiometer Setting — If potentiometer is turned

fully clockwise or counterclockwise, potentiometer will be out

of the allowable range, and an error will result.

Faulty Wiring — If wiring between the potentiometer and the

processor board is incorrect, an error will occur.

Potentiometer Failure — If potentiometer is shorted or open,

potentiometer will be out of range and an error will result.

NOTE: The full range of the potentiometer is not used for the

cooling set point range of 45 F to 70 F. The full scale resistance

of the potentiometer is 10 Kohms.

If a failure occurs, one of the following is a probable cause:

Incorrect Potentiometer Setting — A potentiometer turned

fully clockwise or counterclockwise is outside the valid range

and will cause a failure.

Faulty Wiring — If wiring is incorrect between potentiometer

and processor board or display board, a failure will result.

Potentiometer Failure — If potentiometer is shorted or open, a

failure will result.

CODE 83: ECONOMIZER FEEDBACK POTENTIOME-

TER FAILURE — If potentiometer on economizer motor (P2)

fails, control will use a default value of 0% and economizer

outdoor-air dampers will close. The failure will energize alarm

light and cause an error code of 83 to be displayed when dis-

play button is pushed. This potentiometer is a 5 to 15 Kohm

potentiometer. If potentiometer returns to normal, control will

automatically reset. If a failure occurs, one of the following is

the probable cause.

Faulty Wiring — If the wiring between processor board and

potentiometer is wrong, this will cause a failure.

Potentiometer Failure — If potentiometer is shorted or open,

this will cause a failure.

Economizer Damper Stuck — The control has been pro-

grammed to indicate an error if potentiometer travel is less than

10% of the full range. This would happen if dampers or damp-

er linkage were hung up and could not move properly.

CODE 84: RESET LIMIT POTENTIOMETER FAILURE —

This code is applicable only if reset is being used. If reset is

being used, DIP switch 2 must be in the ON position. This

potentiometer (P3) is located on the accessory board. If poten-

tiometer setting is less than 0° F or greater than 80 F, alarm

light will be energized, a diagnostic code of 84 will be dis-

played if display button is pushed, and reset will be terminated.

The full-scale resistance of potentiometer is 10 Kohms, but

when installed on the accessory board in parallel with the other

2 potentiometers, measured resistance will be 3.3 Kohms. This

failure will automatically reset once potentiometer returns to

normal. If a failure occurs, one of the following is the probable

cause:

DIP Switch Problem — DIP switch 2 is in the ON position

and the accessory board is not installed (accessory board is

standard on these units so it should always be on the unit).

Incorrect Potentiometer Setting — A potentiometer turned

fully clockwise or counterclockwise is outside the valid range

and will result in a failure.

CODE 87: WARM-UP TEMPERATURE SET POINT FAIL-

URE — Applicable only if morning warm-up is used. Whether

or not unit is equipped with electric resistance heaters, use of

the morning warm-up function is recommended if the unit is

shut down at night or over weekends. In this application, cool-

ing will remain off and the outdoor-air damper will stay closed

until heat load from the occupied space elevates return-air tem-

perature to the warm-up set point. If warm-up function is used,

DIP switch 4 must be in the ON position. The potentiometer

(P6) is located on the accessory board. If potentiometer is set at

less than 0° F or more than 95 F, alarm light will be energized,

a diagnostic code of 87 will appear on the display when dis-

play button is pushed, and control will use a default value of

40 F. If setting is between 0° F and 40 F, control will use a

value of 40 F but no diagnostic code will be displayed; if set-

ting is between 80 F and 95 F, control will use a value of 80 F

but no diagnostic code will be displayed.

Faulty Wiring — If the wiring between the potentiometer and

the processor board is incorrect, a failure will result.

Potentiometer Failure — If potentiometer is shorted or open, a

failure will occur.

The potentiometer full-scale resistance is 10 Kohm, but

when wired in parallel with other potentiometers on the acces-

sory board, measured resistance is 3.3 Kohm.

The failure will automatically reset once potentiometer re-

turns to normal. If a failure occurs, one of the following is the

probable cause:

DIP Switch 4 — If this switch is in the ON position and the

accessory board is not installed (accessory board is standard on

these units, so it should always be on the unit).

Incorrect Potentiometer Setting — If potentiometer is turned

fully clockwise or counterclockwise, potentiometer will be out

of the allowable range, resulting in an error.

Faulty Wiring — If the wiring between the potentiometer and

the processor board is incorrect, an error will occur.

PROCESSOR BOARD CHECKOUT — Refer to Fig. 49 and

50 for location of terminal pins and test points.

Step 1 — Check Transformer Input to the Board — Con-

nector J4 is used to connect the control transformer to the pro-

cessor board.

1. Set the volt-ohmmeter to ac voltage with a range setting

of approximately 30 v.

2. Turn control switch to ON position.

3. Check voltage at following terminals on pin terminal con-

nector J4:

TERMINALS

VOLTAGE (AC)

Potentiometer Failure — If potentiometer is shorted or open,

potentiometer will be out of range, resulting in an error.

1 to 2

4 to 6

5 to 6

5 to 4

15.3 to 20.9

16.2 to 22.0

8.1 to 11.0

Thermistor Troubleshooting — The VAV control

system uses thermistors to measure temperatures of the enter-

ing and supply air, as well as the saturated condensing tempera-

tures of the refrigerant circuits. The resistance versus tempera-

ture and electrical characteristics for all thermistors in the sys-

tem are identical. To obtain an accurate reading, a high-

impedance meter (such as a digital meter) must be used.

Thermistors in the VAV control system have a 5 vdc signal

applied across them any time the unit control circuit is ener-

gized. The voltage drop across the thermistor is directly pro-

portional to the temperature and resistance of the thermistor.

To determine temperatures at the various thermistor loca-

tions, disconnect the thermistor from the processor board and

measure the resistance across the appropriate thermistor using

a high-quality digital ohmmeter. Use the resistance reading to

determine the thermistor temperature.

The microprocessor has been programmed to check the op-

eration of the thermistors. If the measured temperature is out-

side of the range of –24 to 225 F or 98,010 to 282 ohms, then it

will be treated as a sensor failure and a diagnostic code will be

displayed. See Table 19 for sensor temperatures versus resis-

tance drop. It is also possible to check the operation of the ther-

mistors using the quick test routine.

4. If voltage is not within range, check primary side.

115-v transformer — 104 to 127 vac

230-v transformer — 207 to 254 vac

5. If primary voltage is not correct, check system fuse, trans-

former, ON-OFF switch, and wiring. If these are okay,

contact power company.

6. If primary voltage is correct, but secondary voltage (24 v

± 10%) is incorrect, replace transformer.

7. Turn control switch to OFF position.

Step 2 — Check Processor Board Power Supply

1. Set meter to approximately 20 vdc.

2. Turn power to OFF position.

3. Connect negative lead to TP18.

4. Turn power switch to ON position and press display but-

ton to enter Quick Test mode.

5. Check voltage between TP18 and each of the following

test pins:

TEST PIN

VOLTAGE (DC)

TP3

TP4

TP6

TP10

TP14

TP15

TP7

+10

+12

If a thermistor has failed or the wire is damaged, replace the

complete assembly. Do not attempt to splice the wires or repair

the assembly.

+12

–5*

Electronic Controls Checkout — The following will

help determine whether a processor board, a relay board, dis-

play set point board, accessory board, or 2-step demand limit

module is faulty.

*If not using a digital meter, leads must be reversed.

6. If voltage is incorrect, replace processor board.

7. Turn power to ON position.

Step 3 — Check Voltage Tolerance Circuitry

1. Turn power to OFF position.

2. Negative test probe on TP18 and system in Quick Test

mode.

3. Check voltage TP18 to TP9.

4. If voltage is greater than 11 vdc, recheck transformer in-

put voltage.

5. If transformer is okay, replace processor board.

6. Turn power to ON position.

Before checking out any board, do the following:

1. At initial start-up, enter the Quick Test mode. This test

will determine if all components are connected and oper-

ating properly.

2. If system has been operating and a malfunction occurs,

check display for diagnostic codes. Use diagnostic chart

located on inner panel of access door to control box sec-

tion of unit; this chart will help determine probable cause

of failure.

These 2 steps will help determine if a component other than

a board is at fault or if the problem is external to control circuit.

Step 4 — Check Processor Reset Line

1. Turn power to OFF position.

2. Negative probe on TP18.

A volt-ohmmeter will be needed to troubleshoot boards. A

digital meter is preferred but a Simpson 260 or equivalent will

work.

3. Check voltage TP18 to TP11.

4. If voltage is greater than +3 vdc, reset power and recheck.

5. If voltage is still incorrect, replace processor board.

6. Turn power to ON position.

To prevent damage to solid-state electronic components on

boards, meter probes should only be placed on terminals

and test points listed in following sections. Do not short the

electrical components, and use extreme care while working

on the processor board.

Step 5 — Check Relay Board Outputs from the Processor

Board — This step involves checking the output signals from

relays K1-K3 on the relay board.

Table 23 on pin terminal connector J9. See Fig. 51 for J9

details.

Step 6 — Display Board Connection Checkout

1. Turn power to OFF position.

2. Connect negative test probe to TP19 (meter still set to

dc).

3. Turn switch to ON position and enter Quick Test mode.

4. Connect positive test probe to terminal 14 on pin terminal

connector J9, and check voltage from TP19 to terminal

14 on pin terminal connector J9.

5. If not 112 ± 1 vdc, replace processor board.

6. Turn switch to OFF position.

7. Remove negative test probe from TP19. Connect positive

test probe to TP15.

8. Turn switch to ON position and go into Quick Test mode.

9. Place negative lead on terminals shown in Table 24, and

check voltage between TP15 and terminals shown in

2. Disconnect the ribbon cable.

3. Connect negative lead of meter to TP18.

4. Turn power to ON position and go into Quick Test mode.

5. Place the other lead on terminals shown in table below,

and check voltage at pin terminals on pin terminal con-

nector J10 (see Fig. 52 for pin terminal connector J10

details):

PIN TERMINAL

VOLTAGE (DC)

20*

22*

2.5

*Voltage reading is dependent on the meter’s impedance. Readings

may vary with different meters.

Fig. 51 — Relay Board Pin Terminal Connector (J9)

LEGEND

— Pin Terminal Strip

TP — Test Pin

Fig. 49 — Processor Board Test Points

Table 24 — Voltage Reading

J9 PIN NUMBERS

QUICK TEST

STEP NO.

R10

C10

R11

R12

C12

R13

C13

9 10 11 12 13

1.-2.3.

2.4.

2.5.

2.6.

2.7.

2.8.

2.9.

3.0.

3.1.

3.2.

3.3.

C11

12 0

12 0 12

12 0

12 12

CR9

CR10

CR11

CR12

CR13

12 0

0 12

NOTES:

1. Pins shown in boldface type will only be energized for 10 seconds.

All other pins will be energized continuously while at the proper

quick test step. The control will only stay in the Quick Test routine

for 10 minutes unless the display button is pressed.

2. Acceptable range for the voltage reading:

0 v — 0 to 4 v

CR1

CR2

CR3

CR4

CR5

C19

CR6

CR7

CR8

12 v — 11 to 13 v

3. If any of these voltages are not measured, replace the processor

board.

LEGEND

CR — Control Relay

— Pin Terminal Strip

— Relay

Fig. 50 — Relay Board Test Points

6. If voltage is not correct, replace processor board.

Step 7 — Potentiometer Connection Checkout

1. Turn power to OFF position.

2. Remove plug connection from pin terminal strip J3.

3. Connect negative meter lead to terminal 2 of J3.

4. Turn switch to ON position and go into Quick Test mode.

Table 25 — Pin Terminal Connector J1 Voltages

TERMINAL

VOLTAGE

(vdc 0.25 v)

5. Place the other lead on terminals shown in table below,

and check voltage at pin terminals on terminal connector

J3:

PIN TERMINAL

VOLTAGE (DC)

2.5

10*

13*

14*

*Voltage reading is dependent on the meter’s impedance. Readings

Step 9 — Thermistor Input Connector Checkout

1. Turn power to OFF position.

2. Disconnect all plugs for pin terminal connector J2 and

mark them for later replacement.

3. Connect a negative test lead to test pin TP18.

4. Turn power to ON position, and enter the Quick Test

routine.

5. Place the other lead on terminals shown in Table 26, and

check the voltages.

6. If voltages are incorrect (per Table 26), replace processor

board.

7. Turn power to OFF position, and replace the plugs re-

moved in Step 2.

8. Turn power to ON position.

may vary with different meters.

6. If voltage is not correct, replace processor board.

Step 8 — Thermistor Input Connector Checkout

1. Turn power to OFF position.

2. Remove the thermistor connections from pin terminal

connector J1, and mark them for later replacement.

3. Connect the negative test lead to test pin TP18.

4. Turn power to ON position, and enter the Quick Test

routine.

5. Place the other lead on terminals shown in Table 25, and

check the voltages.

6. If voltages are incorrect (per Table 25), replace processor

board.

7. Turn power to OFF position, and replace the thermistor

connections removed in Step 2.

8. Turn power to ON position.

Table 26 — Pin Terminal Connector J2 Voltages

TERMINAL

VOLTAGE

(vdc 0.25 v)

If Steps 1 through 9 have been competed and the unit still

will not function properly, replace the processor board.

Fig. 52 — Display Board Pin Terminal Connector

(J10)

RELAY BOARD TROUBLESHOOTING — The relay board

contains 13 electromechanical relays. The small relays are

24 vac, and the large relays are 115 vac. These relays are con-

trolled by the processor through the ribbon cable attached to

the relay board.

The following procedure can be used to check out the oper-

ation of the relays. To do this, turn the control ON/OFF switch

to the OFF position, and remove the wiring connectors con-

nected to pin terminal connectors J5 and J6. Set the meter for

resistance. If the contacts do not close at the required quick test

step, check the relay outputs from the processor board.

Table 28 — Terminal Strip J5 Connector

Resistance Reading

J5 PIN NUMBERS

QUICK TEST

STEP NO.

1. to 2.5.

2.6

2.7.

2.8.

2.9. to 3.3.

∞

LEGEND

∞ — Infinity

Relay Board Checkout (Fig. 5)

Step 1 — Low-voltage relay resistance check.

1. Turn switch to OFF position.

Step 2 — Check the Display LEDs

1. Enter Quick Test mode.

2. Remove plug connection from terminal strip J6.

2. If 88 is not displayed, replace display board.

3. Set meter to measure resistance. Connect negative test

lead to both terminals 11 and 12 of J6.

4. Turn switch to ON position and go into Quick Test mode.

Step 3 — Check Set Point Potentiometer — Advance the

display to quick test step 1.9. to determine if this potentiometer

is set and connected properly.

Step 4 — Check Display Switch — Press switch. If switch

does not click, it is faulty and the display will be energized con-

tinuously. The switch is an integral part of display board and

cannot be replaced separately.

ACCESSORY BOARD CHECKOUT — The accessory board

can be completely checked using quick test steps 2.0., 2.2., and

2.3. It can also be checked out as follows:

1. Remove the accessory board connector from the proces-

sor board and connect an ohmmeter to terminals 3 and 4

on the connector. Numbers are marked on the connector.

See Fig. 15.

2. Set the meter to 10,000 ohms. The resistance value ob-

tained should be 3,333 ohms. Adjust the potentiometers

and the resistance value should not change.

5. Place other meter lead on terminals shown in Table 27

and check resistances at each quick test step.

6. If these resistances are not correct and relay board outputs

from processor board have been checked out, replace re-

lay board.

Step 2 — High-voltage relay resistance check.

1. Turn switch to OFF position.

2. Remove plug connection from terminal connector J5.

3. Connect negative test lead to terminal 8.

4. Check the resistance between terminals 8 and 5 before

entering Quick Test mode. The resistance should be

infinity.

5. Turn switch to ON position and go into Quick Test mode.

3. Connect the ohmmeter to terminals 3 and 6. As the reset

limit potentiometer is turned clockwise, resistance should

increase from 0 to approximately 3,400 ohms.

4. Connect the ohmmeter to terminals 3 and 5. As the econ-

omizer minimum position potentiometer is turned clock-

wise, resistance should increase from 0 to approximately

3,400 ohms.

5. Connect the ohmmeter to terminals 3 and 2. As the

warm-up set point potentiometer is turned clockwise,

resistance should increase from 0 to approximately

3,400 ohms.

If any of the Steps 1 through 5 result in any other ohm read-

ing, replace the board; it cannot be serviced.

TWO-STEP DEMAND LIMIT CONTROL MODULE

(DLCM) TROUBLESHOOTING — If a problem is suspected

in the DLCM board, use the following test procedure:

The board can only be checked when it is connected to the

processor and the processor is energized so that the DLCM is

supplied with 5 vdc power. The terminals referenced are shown

in Fig. 16. Potentiometers P1 and P2 refer to the DLCM poten-

tiometers.

6. Place other meter lead on terminals shown in Table 28

and check resistance at each quick test step.

7. If these resistances are not correct and relay board outputs

from processor board have been checked per Processor

Board Checkout section on page 48, replace relay board.

DISPLAY BOARD CHECKOUT

Step 1 — Check the Output Voltage from Processor Board

to the Relay Board — Refer to Step 6 — Display Board Con-

nection Checkout section on page 49.

Table 27 — Terminal Strip J6 Connection

Resistance Reading

J6 PIN NUMBERS

QUICK TEST

STEP NO.

1. to 2.3.

2.4.

∞

2.5.

2.6.

2.7.

2.8.

2.9.

3.0.

3.1.

3.2.

∞

IMPORTANT: Be careful to avoid damaging the con-

nector or the processor board when taking the voltage

readings.

∞

3.3.

∞

LEGEND

∞ — Infinity

NOTE: Pins shown in boldface type will be energized for only

10 seconds. All other pins will be energized continuously while at the

proper quick test step. The control will remain in the Quick Test

mode for only 10 minutes unless the display button is pressed.

Test under the following conditions:

•

No power to IN1 or IN2

Terminal 1 to 2 should read 4.5 vdc ±0.1 v

Terminal 2 to 3 should read 5.0 vdc ±0.1 v

Power to IN2 or to both IN1 and IN2, and P2 set at 24%

Terminal 1 to 2 should read 1.5 vdc ± 0.1 v

LIMIT SWITCHES

CAPACITOR

NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc as

the setting of P2 is varied between 0% and 49%.

Terminal 2 to 3 should read 5.0 vdc ± 0.1 v

•

Power to IN1 only and P1 set at 50%

Terminal 1 to 2 should read 2.5 vdc ± 0.1 v

Terminal 2 to 3 should read 5.0 vdc ± 0.1 v

NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc as

the setting of P2 is varied between 50% and 100%.

NOTE: If the voltages listed in these 3 tests are not ob-

tained during testing, the DLCM board must be replaced.

ECONOMIZER

MOTOR

WINDING

(OPEN)

CCW

WINDING

(CLOSE)

Enthalpy Sensor Checkout — To test operation of

BRAKE

WINDING

enthalpy sensor, see Table 29.

Table 29 — Enthalpy Sensor Checkout

EXPECTED RESULT

AND RESPONSE

TEST

Outdoor-air sensor:

Milliammeter reading should be

between 3 and 24 mA if sensor

is operating correctly. If reading

FEEDBACK

POTENTIOMETER

Enthalpy sensor + terminal

should be connected to +

terminal on motor. Connect the is 0 mA, the sensor is either

positive terminal of a DC

wired backwards or is defective.

milliammeter to the S terminal

of the sensor and the negative

terminal of the meter to S_O

terminal of the enthalpy board.

BLU

RED

YEL

Indoor-air sensor:

Milliammeter reading should be

between 3 and 24 mA if sensor

is operating correctly. If reading

Enthalpy sensor + terminal

should be connected to +

AUX. SWITCH

terminal on motor. Connect the is 0 mA, the sensor is either

LEGEND

CCW — Counterclockwise

CW — Clockwise

positive terminal of a DC

wired backwards or is defective.

milliammeter to the S terminal

of the sensor and the negative

terminal of the meter to S_R

terminal of the enthalpy board.

Fig. 53 — Damper Motor Connection Diagram (VAV)

Economizer Motor — All control of the motor (i.e.,

enthalpy changeover, minimum position control and mixed air

control) is accomplished from the main unit microprocessor

through a relay board. Service and installation instructions

for the unit should be consulted to verify proper operation of

these controls. The economizer motor may be checked out sep-

arately. See Fig. 52 for VAV economizer motor connection

information.

Supply Fan Variable Frequency Drive

Factory-installed optional VFD is located near the supply

fan and motor. During any service work or programming at

the VFD, operation of the fan and motor is not desirable.

Either disable the supply fan or install an accessory VFD

remote display.

Motor Test

Apply 24 volt AC power to terminals T1 and T2 of motor.

Connections to motor terminals 2 and 3 must be disconnected

NOTE: The VFDs (part no. TOSVERT130-E3) are specially

modified for use on Carrier equipment. Some specifications

and control configuration defaults for Carrier applications will

differ from the VFD manufacturer manual included in the

packet. See Table 30 for listing of Carrier-specific default

values.

A Motor Test

Jumper 1 to

replace motor.

A Expected Result and Response

Motor drives open; if not, 2 at motor

B Motor Test

Jumper 1 to

3 at motor

B Expected Result and Response

Motor drives closed; if not,

replace motor.

STANDARD TRANSDUCER CONTROL — The VFD mon-

itors and controls duct pressure (DP) via a differential pressure

transducer. The pressure transducer is located in the auxiliary

control box (034-048 units) or in the supply fan compartment

(see Fig. 34). The pressure transducer’s low pressure reference

port is connected to the outside of the unit cabinet by a factory-

installed tubing section. The pressure transducer’s high pres-

sure reference point must be field-connected to the duct pres-

sure pick-up (field-supplied and installed in the supply duct).

P24

LOW LOW

SI S2

RCH

RES

P24

FLB

FLA

AM CC CC

IV FP

FLC

4-20mA

The DP transducer monitors the static pressure in the supply

duct and provides a 4 to 20 mA signal directly to the VFD. (Re-

fer to Table 13 for transducer output signal [mA] for actual duct

static pressure.) The internal logic of the VFD compares this

signal representing actual duct pressure to the user-configured

DP set point. The VFD automatically adjusts its output to the

supply fan motor to maintain the desired DP set point. When

operating with the factory-standard DP transducer, the internal

PID logic of the VFD is enabled. EXTERNAL SIGNAL

CONTROL — If the VFD is to be controlled by an external

control system other than the factory supplied pressure trans-

ducer, the internal PID logic function of the VFD must be dis-

abled. To disable the PID control:

Fig. 54 — Supply Fan Variable Frequency Drive

Terminal Block (Size 034-048 Units)

SI S2

RCH

RES

P24

LOW LOW

P24

FLB

FLA

AM CC CC

IV FP

FLC

1. Disconnect and lock out all power to the Carrier rooftop

unit.

2. Remove the VFD access cover.

4-20mA

Fig. 55 — Supply Fan Variable Frequency Drive

Terminal Block (Size 054-104 Units)

Ensure the “CHARGE” lamp on the VFD is unlit. This

may up to 4 minutes. The “CHARGE” lamp indicates that

the main capacitors in the VFD are charged. Internal com-

ponents of the VFD should not be touched until the

“CHARGE” lamp is completely out. Electrical shock can

cause injury or death.

VFD OPERATION — When troubleshooting the VFD, check

first that all required conditions for VFD operation are

satisfied.

For the VFD to run, the following conditions must be met at

the VFD:

1. Drive enable jumper is installed from terminals CC-ST

(factory supplied) (see Fig. 54 and 55).

2. Proper rotation jumper is installed at terminals R-CC (re-

verse rotation, factory supplied) or terminals F-CC (for-

ward rotation, factory supplied).

3. Install a jumper across S2-CC (see Fig. 54 and 55 for

VFD terminal board connections).

4. Remove factory-supplied cable attached to IV and CC.

5. Remove other end of the same cable from the pressure

sensor.

6. Connect field supplied speed reference (4 to 20 mA)

across terminals IV-CC.

UNIT SIZES

ROTATION

JUMPER

034-048

054-074

078-104

Reverse

Forward

R-CC

F-CC

7. Disable the supply fan motor operation.

8. Reconnect power to the unit and VFD.

9. Reprogram the VFD to accept an external reference (in

the Utility parameters group [Gr.Ut], set parameter item

Fnod [no.312] = 4).

3. Emergency stop jumper is installed from terminals

S4-CC (factory supplied).

4. A 4 to 20 mA signal is applied across terminals IV-CC

(from pressure transducer, factory supplied).

10. Enable supply fan motor and return power to the unit.

SUPPLY FAN MOTOR OVERLOAD PROTECTION — The

VFD provides operating overload protection for the supply fan

motor. The factory has programmed the VFD overload func-

tion to match the factory-installed motor (motor size and effi-

ciency). If the supply fan motor is changed from the original

factory selection, the overload value may need to be changed

by the service person. Contact your local Carrier representative

for assistance in determining the proper overload setting.

5. DIP switch SW1 (located on the VFD’s printed circuit

control panel) must be set to ‘‘I’’ (indicating usage of a 4

to 20 mA input signal at terminals ‘‘IV’’).

6. Speed Control (located on the VFD’s keypad/display) set

for ‘‘Remote’’ (press the ‘‘Speed Ctrl’’ button until LED

‘‘Remote’’ is illuminated).

7. Programmed according to Carrier defaults.

8. Duct Pressure set point established by user, or use factory

default (30 Hz indicating 2.50-in. wg) (see Table 13).

NOTE: Variable frequency drive size is matched to factory-

installed motor size. Do not increase motor size without also

changing to equivalent VFD size.

Table 30 — Carrier Default Program Parameter Values (Supply Fan VFD)

PARAMETER GROUP

PARAMETER

ACC1

DEC1

DEFAULT VALUE

60.0 Sec

60.0 Hz

10.0 Hz*

Luln

20%

F-P3

0.0 Hz

100%

SEtP

(Setup)

F-P4

tHr1

StC1

StL1

OLN

tYP

60 Hz

See Table 32

110%

60 Hz

Gr.F

(Fundamental)

FbP1

Fbln

.30

2 sec

Gr.Fb

(Feedback)

GFS

P1LL

PuL

PuUl

PuLL

Fsor

Sr.n

SrN1

60 Hz

Gr.SF

(Frequency Settings)

1* (054-104 only)

0* (054-104 only)

Gr.Pn

(Panel Control)

1t0

1t1

1t2

Gr.St

(Terminal Selection)

1t3

1t4

UuC

UuCt

ArSt

Cnod

bLSF

Fnod

bLPn

Gr.Pr

(Protection)

1* (054-104 only)

Gr.Ut

(Utility)

*These settings differ from the Toshiba defaults and are required for Carrier applications.

NOTE: To restore original factory settings, change tYP to 6 in Setup mode (SEtP). This restores the VFD original factory settings.

VFD OPERATIONAL STATUS — The VFDs contain ex-

tensive self-diagnostic functions which are accessed through

the VFD display panel (located on the front of the VFD or at a

remote location when the accessory remote display package

has been installed).

logic of the power exhaust VFD compares this signal repre-

senting actual duct pressure to the user-configured BP set

point. The power exhaust VFD automatically adjusts its output

to the power exhaust fan motor to maintain the desired BP set

point. When operating with the factory-standard BP transducer,

the internal PID logic of the power exhaust VFD is enabled.

EXTERNAL SIGNAL CONTROL — If the power exhaust

VFD is to be controlled by an external control system other

than the factory-supplied pressure transducer, the internal PID

logic function of the power exhaust VFD must be disabled. To

disable the PID control:

1. Disconnect and lock out all power to the Carrier rooftop

unit.

If using the VFD display panel, disconnect all power to

the unit and the VFD before entering unit, or use the

accessory remote display module. Disable supply fan and

motor operation before accessing VFD-mounted display

module.

When power is first supplied to the VFD, the display auto-

matically starts with the frequency monitor function of its stan-

dard monitor mode. In the frequency monitor function, the out-

put frequency is displayed. Push the S/P/M (Setup/ Program/

Monitor) key to switch to the Mode Selection menu. Push the

S/P/M key again to toggle the display back to the standard

monitor mode.

From the Mode Selection menu, the service person can

view all of the monitored status variables, including up to four

user-selected variables and any trip history in the memory.

2. Remove the VFD access cover.

Ensure the “CHARGE” lamp on the VFD is unlit. This

may up to 4 minutes. The “CHARGE” lamp indicates that

the main capacitors in the VFD are charged. Internal com-

ponents of the VFD should not be touched until the

“CHARGE” lamp is completely out. Electrical shock can

cause injury or death.

Refer to the separate VFD Operation Manual for detailed

instructions on accessing diagnostic information, initiating

troubleshooting, and clearing any trip history.

RESTORING FACTORY VFD DEFAULTS — The original

factory configuration values are saved in the memory of the

VFD and can be restored by the service person if required.

There are two types of saved file data: Carrier-factory settings

(factory programmed settings made to the VFD which apply

specifically to the unit it is installed on) and standard defaults

for general Carrier unit use.

The Carrier-factory settings are maintained as user settings.

These can be restored by entering the Setup mode (in the

S/P/M menu) and setting parameter tYP = 6 on the keypad/

display. This will recall the specific factory defaults for this

unit.

3. Install a jumper across S2-CC (see Fig. 56 for power ex-

haust VFD terminal board connections).

4. Remove factory-supplied cable attached to IV and CC.

5. Remove other end of the same cable from the pressure

sensor.

6. Connect field-supplied speed reference (4 to 20 mA)

across terminals IV-P24.

7. Disable the supply fan motor operation.

8. Reconnect power to the unit and power exhaust VFD.

9. Reprogram the power exhaust VFD to accept an external

reference (in the Utility parameters group [GR.Ut], set

parameter item Fnod [no.312] = 4).

10. Enable supply fan motor and return power to the unit.

Occasionally it may be necessary to restore the VFD de-

faults to the general Carrier use values. These are stored in an

OPTION ROM (read-only memory chip). However, some

variables may need to be manually changed to match the spe-

cific unit’s factory default settings. To recall the general Carrier

defaults, enter the Setup mode and set parameter tYP = 3. Re-

fer to Table 31 for items requiring manual adjustment.

Table 31 — Supply Fan VFD Required

User Adjusted Defaults

SIZES

All

ITEM

Motor overload settings (see Table 32)

1. Check jumper CC-F

2. Gr.UT/bLSF = 1

054-104

3. Gr.SF/Sr.n = 1

Power Exhaust Variable Frequency Drive

(48FM and 50FM,FS)

4. Gr.SF/SrN1 = 0

5. SEtP/tYP = 5 (Save User Settings)

NOTE: The VFDs (part no. TOSVERT130-E3) are specially

modified for use on Carrier equipment. Some specifications

and control configuration defaults for Carrier applications

will differ from the VFD manufacturer manual included in the

packet. See Table 33 for listing of Carrier-specific default

values.

Table 32 — Supply Fan Motor Overload Settings

UNIT

IFM HP

DESIGNATION

VOLTAGE

tHr1

SETTING

DESIGNATION

UNIT 48/50

AND

Model No.

Position 12

Model No.

Position 15

STANDARD TRANSDUCER CONTROL — The VFD

monitors and controls building pressure (BP) via a differential

pressure transducer. The pressure transducer is located in the

auxiliary control box. The pressure transducer’s high-pressure

reference port is connected to the outside of the unit cabinet by

a factory-installed tubing section. The pressure transducer’s

low-pressure reference point must be field-connected to the

building pressure pick-up (field-supplied and installed in the

building).

The BP transducer monitors the static pressure in the occu-

pied space and provides a 4 to 20 mA signal directly to the

power exhaust VFD. (Refer to Table 30 for transducer output

signal [mA] for actual building static pressure.) The internal

And

82.0

86.0

80.0

78.0

FK,FY,

JK,JY

FKX,FKY,

JKX,JKY

LEGEND

IFM — Indoor Fan Motor

POWER EXHAUST FAN MOTOR NO. 1 OVERLOAD

PROTECTION — The VFD provides operating overload

protection for the supply fan motor. The factory has pro-

grammed the power exhaust VFD overload function to match

the factory-installed motor (motor size and efficiency). If the

power exhaust fan motor is changed from the original factory

selection, the overload value may need to be changed by the

service person. Contact your local Carrier representative for

assistance in determining the proper overload setting.

P24

LOW LOW

SI S2

RCH

RES

P24

FLB

FLA

AM CC CC

IV FP

FLC

NOTE: Variable frequency drive size is matched to factory-

installed motor size. Do not increase motor size without also

changing to equivalent VFD size.

4-20mA

Fig. 56 — Variable Frequency Drive Terminal Block

Table 33 — Carrier Power Exhaust VFD Default Program Parameter Values

PARAMETER GROUP

PARAMETER

DEFAULT VALUE

ACC1

DEC1

60.0 Sec

59.8 Hz

10.0 Hz*

Luln

20%

F-P3

0.0 Hz

98%

SEtP

(Setup)

F-P4

tHr1

StC1

StL1

OLN

tYP

60 Hz

See Table 35

110%

60 Hz

Gr.F

(Fundamental)

FbP1

Fbin

.30

2 sec

Gr.Fb

(Feedback)

GFS

P1LL

PuL

PuUl

PuLL

Gr.SF

Fsor

60 Hz

(Frequency Settings)

Gr.Pn

(Panel Control)

1t0

1t1

1t2

1t3

Gr.St

1t4

Ot1

Ot2

100*

15*

(Terminal Selection)

Ot2d

Ot2H

UuC

UuCt

ArSt

Cnod

Fnod

bLPn

Gr.Pr

(Protection)

Gr.Ut

(Utility)

*These settings differ from the Toshiba defaults and are required for Carrier applications.

NOTE: To restore original factory settings, change tYP to 6 in SEtup mode (SEtP).

This restores the VFD original factory settings.

POWER EXHAUST VFD OPERATION — When trouble-

shooting the power exhaust VFD, check first that all required

conditions for power exhaust VFD operation are satisfied.

Refer to the separate VFD Operation Manual for detailed

instructions on accessing diagnostic information, initiating

troubleshooting, and clearing any trip history.

For the power exhaust VFD to run, the following conditions

must be met at the power exhaust VFD:

1. Drive enable jumper is installed from terminals ST-CC

(factory supplied) (see Fig. 56).

2. Proper rotation jumper is installed at terminals R-CC (re-

verse rotation, factory supplied).

3. Emergency stop jumper is installed from terminals

S4-CC (factory supplied).

RESTORING FACTORY POWER EXHAUST VFD

DEFAULTS — The original factory configuration values are

saved in the memory of the power exhaust VFD and can be

restored by the service person if required. There are two types

of saved file data: Carrier-factory settings (factory pro-

grammed settings made to the power exhaust VFD which

apply specifically to the unit it is installed on) and standard

defaults for general Carrier unit use.

The Carrier-factory settings are maintained as user settings.

These can be restored by entering the Setup mode (in the

S/P/M menu) and setting parameter tYP = 6 on the keypad/dis-

play. This will recall the specific factory defaults for this unit.

Occasionally it may be necessary to restore the power ex-

haust VFD defaults to the general Carrier use values. These are

stored in an OPTION ROM (read-only memory chip). Howev-

er, some variables may need to be manually changed to match

the specific unit’s factory default settings. To recall the general

Carrier defaults, enter the Setup mode and set parameter

tYP = 3. Refer to Tables 34 and 35 for items requiring manual

adjustment.

4. A 4 to 20 mA signal is applied across terminals IV-P24

(from pressure transducer, factory supplied).

5. DIP switch SW1 (located on the VFD’s printed circuit

control panel) must be set to “I” (indicating usage of a 4

to 20 mA input signal at terminals “IV”).

6. Speed Control (located on the VFD’s keypad/display) set

for “Remote” (press the “Speed Ctrl” button until LED

“Remote” is illuminated).

7. Programmed according to Carrier defaults.

8. Building Pressure set point established by user, or

use factory default (30 Hz indicating 0.0 in. wg) (see

Table 15).

POWER EXHAUST VFD OPERATIONAL STATUS —

The power exhaust VFDs contain extensive self-diagnostic

functions which are accessed through the power exhaust VFD

display panel (located on the front of the power exhaust VFD

or at a remote location when the accessory remote display

package has been installed.)

Table 34 — Power Exhaust VFD Required

User Adjusted Defaults

UNIT

ALL

ITEM

Motor Overload Settings (See Table 35)

Gr.St/Ot1 = 4

Gr.St/Ot2 = 2

Gr.St/Ot2d = 5

Gr.St/Ot2H = 100

Gr.St/LF = 15

If using the VFD display panel, disconnect all power to

the unit and the VFD before entering unit, or use the

accessory remote display module. Disable supply fan and

motor operation before accessing VFD-mounted display

module.

SEtP/UL = 59.8

SEtP/P4 = 98

Table 35 — Power Exhaust Motor

Overload Settings

When power is first supplied to the power exhaust VFD, the

display automatically starts with the frequency monitor func-

tion of its standard monitor mode. In the frequency monitor

function, the output frequency is displayed. Push the S/P/M

(Setup/Program/Monitor) key to switch to the Mode Selec-

tion menu. Push the S/P/M key again to toggle the display

back to the standard monitor mode.

From the Mode Selection menu, the service person can

view all of the monitored status variables, including up to four

user-selected variables and any trip history in the memory.

MODEL NUMBER

POSITION 16

TOTAL

MOTOR HP

(ea)

tHr1

SETTING

H, T

J, V

K, W

L, X

M, Y

97.3

100.0

93.5

92.3

Unit Wiring — A typical wiring schematic is shown in

Fig. 57.

LEGEND AND NOTES FOR FIG. 57

ALM

— Alarm

IGVM — Inlet Guide Vanes Motor

— Contactor

LAT

LPS

— Leaving-Air Temperature

— Low-Pressure Switch

— Circuit Breaker

— Control Circuit Breaker

CCB

MTR — Motor

COMP — Compressor

— Main Valve

— Normally Closed

— Normally Open

— Crankcase Heater

— Control Relay

DPS

DPT

EAT

— Differential Pressure Switch

— Discharge Pressure Transducer

— Enering-Air Temperature

— Enthalpy Control

OFC — Outdoor Fan Contactor

OFM — Outdoor (Condenser) Fan Motor

OMR — Outdoor Motor Relay

PCB — Power Exhaust Circuit Breaker

PEC — Power Exhaust Contactor

PEDM — Power Exhaust Damper Motor

PEM — Power Exhaust Motor

P, PL — Plug

ECR

EOR

— Economizer Close Relay

— Economizer Open Relay

EQUIP — Equipment

— Fan Status Switch

GND — Ground

RCB — Return Fan Circuit Breaker

RES — Resistor

HIR

HPS

HTR

IDC

IDM

IFC

— Heat Interlock Relay

— High-Pressure Switch

— Heater Relay

RFC — Return Fan Contactror

RFM — Return Fan Motor

SCT — Saturated Condensing Thermistor

— Heater

— Induced Draft Contactor

— Induced Draft Motor

— Indoor (Evaporator) Fan Contactor

— Terminal Block

TRAN — Transformer

— Unloader

IFCB — Indoor Fan Circuit Breaker

IFM

IGV

VFD — Variable Frequence Drive

Field Wiring

— Indoor Fan Motor

— Inlet Guide Vanes

Factory Wiring

NOTES:

1.Connect TRAN1 to

for 460 v units. Connect to

for 230 v

units. If 208/230 v units are run with a 208 v power supply con-

nect to

2.Connect TRAN2 to BLK lead for 460 v units. Connect to ORN

lead for 230 v units. If 208/230 v units are run with a 208 v

power supply connect to RED lead.

3.Circuit breaker must trip amps are equal to or less than 156%

FLA (full load amps) for CB1 and CB2. All others are 140%.

4.If any of the original wire furnished must be replaced, it must

be replaced with type 90° C wire or its equivalent.

5.Number(s) indicates the line location of contacts. A bracket

over (2) numbers signifies single pole double throw contacts.

An underlined number signifies a normally closed contact.

Plain numbers (no lines), signify a normally opened contact.

6.Condenser fan motors are thermally protected.

7.Three phase motors are protected under primary single phas-

ing conditions.

SERVICE TRAINING

Packaged Service Training programs are an excellent way to increase your knowledge of the equip-

ment discussed in this manual, including:

• Unit Familiarization

• Installation Overview

• Maintenance

• Operating Sequence

A large selection of product, theory, and skills programs are available, using popular video-based for-

mats and materials. All include video and/or slides, plus companion book.

Classroom Service Training which includes ‘‘hands-on’’ experience with the products in our labs can

mean increased confidence that really pays dividends in faster troubleshooting and fewer callbacks.

Course descriptions and schedules are in our catalog.

CALL FOR FREE CATALOG 1-800-962-9212

[ ] Packaged Service Training

[ ] Classroom Service Training

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

PC 111 Catalog No. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg 62 3-00 Replaces: 48/50F,J-1T

Book 1

Tab 1a 1b

START-UP CHECKLIST

MODEL NO.: _____________________________________

SERIAL NO.: ______________________________________

TECHNICIAN:_____________________________________

DATE: ___________________________________________

I. PRE-START-UP:

VERIFY THAT UNIT IS LEVEL

VERIFY THAT ALL PACKING MATERIALS HAVE BEEN REMOVED FROM UNIT

LOOSEN ALL SHIPPING HOLDDOWN BOLTS AND REMOVE SHIPPING BRACKETS PER INSTRUCTIONS

VERIFY THAT COMPRESSOR SUSPENSION SPRINGS HAVE BEEN LOOSENED PER INSTRUCTIONS

VERIFY OPENING OF ECONOMIZER HOODS

VERIFY INSTALLATION OF EXHAUST HOODS

CONFIRM THAT TUBING FOR SPACE AND SUPPLY DUCT PRESSURES HAS BEEN INSTALLED

VERIFY THAT CONDENSATE CONNECTION IS INSTALLED PER INSTRUCTIONS

VERIFY THAT POWER SUPPLY MATCHES UNIT DATA PLATE

VERIFY THAT ALL ELECTRICAL CONNECTIONS AND TERMINALS ARE TIGHT

CHECK GAS PIPING FOR LEAKS (48FK,JK ONLY)

CHECK THAT INDOOR-AIR FILTERS ARE CLEAN AND IN PLACE

CHECK FAN WHEEL AND PROPELLER FOR LOCATION IN HOUSING/ORIFICE, AND VERIFY SET SCREWS ARE

TIGHT

VERIFY THAT FAN SHEAVES ARE ALIGNED AND BELTS ARE PROPERLY TENSIONED

OPEN SUCTION, DISCHARGE, AND LIQUID LINE SERVICE VALVES

CHECK COMPRESSOR OIL LEVEL SIGHT GLASS AND VERIFY PROPER LEVEL

VERIFY THAT CRANKCASE HEATERS HAVE BEEN ENERGIZED FOR 24 HOURS

CHECK VOLTAGE IMBALANCE

LINE-TO-LINE VOLTS:

(AB + AC + BC)/3 = AVERAGE VOLTAGE =

MAXIMUM DEVIATION FROM AVERAGE VOLTAGE =

VOLTAGE IMBALANCE = 100 X (MAX DEVIATION)/(AVERAGE VOLTAGE) =

IF OVER 2% VOLTAGE IMBALANCE, DO NOT ATTEMPT TO START SYSTEM!

CALL LOCAL POWER COMPANY FOR ASSISTANCE.

II. PRELIMINARY CHECKLIST ITEMS:

CONTROL SETTINGS

DIP SWITCHES SET TO MATCH INSTALLED ACCESSORIES:

SUPPLY AIR SET POINT RESET (DIP SWITCH NO. 4 ON)

MORNING WARM-UP (DIP SWITCH NO. 4 ON)

DEMAND LIMIT (DIP SWITCH NO. 5 ON)

SUPPLY AIR SET POINT (P1) SET BETWEEN 45 AND 70 F

ECONOMIZER MINIMUM POSITION (P5) SET PER PLANS

SUPPLY AIR SET POINT RESET SETTINGS:

RESET INITIATION TEMPERATURE (P7) (TYPICALLY 68 TO 72 F)

RESET LIMIT TEMPERATURE (P3) (TYPICALLY 60 TO 70 F)

MORNING WARM-UP TEMPERATURE (TYPICALLY 50 TO 65 F)

IGV/VFD DUCT PRESSURE SET POINT PER PLANS

BUILDING PRESSURE (MODULATING POWER EXHAUST) SET PER PLANS

DEMAND LIMIT SETTINGS PER PLAN:

SINGLE STEP DEMAND LIMIT (P4) SET (TYPICALLY 25 TO 50%)

TWO-STEP DEMAND LIMIT

DLCM-P1 SET (TYPICALLY 50 TO 75%)

DLCM-P2 SET (TYPICALLY 0 TO 25%)

OCCUPIED/UNOCCUPIED SWITCH INSTALLED PER FIG. 23 (CLOSE TO START UNIT)

CL-1

III. START-UP

CHECK EVAPORATOR FAN SPEED AND RECORD.

CHECK CONDENSER FAN SPEED AND RECORD.

AFTER AT LEAST 10 MINUTES RUNNING TIME, RECORD THE FOLLOWING MEASUREMENTS:

COMP A1

COMP A2

COMP B1

COMP B2

OIL PRESSURE

SUCTION PRESSURE

SUCTION LINE TEMP

DISCHARGE PRESSURE

DISCHARGE LINE TEMP

ENTERING CONDENSER AIR TEMP

LEAVING CONDENSER AIR TEMP

EVAP ENTERING AIR DB TEMP

EVAP ENTERING AIR WB TEMP

EVAP LEAVING AIR DB TEMP

EVAP LEAVING AIR WB TEMP

COMPRESSOR AMPS (L1)

COMPRESSOR AMPS (L2)

COMPRESSOR AMPS (L3)

ELECTRICAL

SUPPLY FAN AMPS

EXHAUST FAN AMPS

ELECTRIC HEAT AMPS L1

TEMPERATURES

(50 SERIES UNITS ONLY)

OUTDOOR-AIR TEMPERATURE

RETURN-AIR TEMPERATURE

COOLING SUPPLY AIR

PRESSURES

DB (Dry-Bulb)

F WB (Wet-Bulb)

GAS INLET PRESSURE

IN. WG (48 SERIES UNITS ONLY)

GAS MANIFOLD PRESSURE STAGE NO. 1

UNITS ONLY)

IN. WG

STAGE NO. 2

IN. WG (48 SERIES

REFRIGERANT SUCTION

CIRCUIT NO. 1

PSIG

CIRCUIT NO. 2

PSIG

REFRIGERANT DISCHARGE CIRCUIT NO. 1

VERIFY REFRIGERANT CHARGE USING CHARGING CHARTS IN UNIT INSTALLATION INSTRUCTIONS

GENERAL

ECONOMIZER MINIMUM VENT SETTING TO JOB REQUIREMENTS

IV. NOTES

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

Book

Tab

PC 111

Catalog No. 534-763

Printed in U.S.A.

Form 48/50F,J-3T

Pg CL-2

3-00

Replaces: 48/50F,J-1T

1a 1b

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