Carrier Heat Pump 50VT A User Manual

50VT---A  
Performancet 14 SEER Single---Packaged Heat Pump  
System with Puron® (R---410A) Refrigerant  
Single and Three Phase  
2 --- 5 N o m i n a l To n s ( S i z e s 2 4 --- 6 0 )  
Installation Instructions  
NOTE: Read the entire instruction manual before starting the  
installation.  
NOTE: Installer: Make sure the Owner’s Manual and Service  
Instructions are left with the unit after installation.  
TABLE OF CONTENTS  
PAGE  
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 1  
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
RECEIVING AND INSTALLATION . . . . . . . . . . . . . . . . . . 2--9  
Check Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Identify Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Inspect Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Provide Unit Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Roof Curb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Slab Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Provide Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Rig and Place Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Rigging/Lifting of Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Select and Install Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . . 7  
Converting Horizontal Discharge Units to Downflow  
A09033  
(Vertical) Discharge Units . . . . . . . . . . . . . . . . . . . . . . . . . . 7  
Provide for Condensate Disposal . . . . . . . . . . . . . . . . . . . . . . 8  
Install Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . 8  
High--Voltage Connections . . . . . . . . . . . . . . . . . . . . . . . . . 8  
Special Procedures for 208--V Operation . . . . . . . . . . . . . . . 9  
Control Voltage Connections . . . . . . . . . . . . . . . . . . . . . . . . 9  
Standard Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
Transformer Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
Accessory Electric heaters Installation . . . . . . . . . . . . . . . . . 9  
Sequence of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
PRE--START--UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17  
START--UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17--20  
Checking Cooling & Heating Control Operation . . . . . . . . 17  
Check for Refrigerant Leaks . . . . . . . . . . . . . . . . . . . . . . . . . 17  
Start--Up Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17  
Checking & Adjusting Refrigerant Charge . . . . . . . . . . . . 18  
Indoor Airflow & Airflow Adjustments . . . . . . . . . . . . . . 18  
Continuous Fan Operation . . . . . . . . . . . . . . . . . . . . . . . . 19  
Defrost Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20  
Quiet Shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20  
Defrost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20  
MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23--28  
Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23  
Indoor Blower and Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . 23  
Outdoor Coil, Indoor Coil, & Condensate Drain Pan . . . . . . 26  
Outdoor Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26  
Electrical Controls and Wiring . . . . . . . . . . . . . . . . . . . . . . . 26  
Refrigerant Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26  
Indoor Airflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26  
Metering Devices-- TXV & Piston . . . . . . . . . . . . . . . . . . . . 26  
Pressure Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
Loss of Charge Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
High Pressure Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
Fig. 1 -- Unit 50VT--A  
Copeland Scroll compressor (Puron Refrigerant) . . . . . . . . . 27  
Refrigerant System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
Refrigerant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
Compressor Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
Servicing Systems on Roofs with Synthetic Materials . . . . 27  
Liquid Line Filter Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
PuronR (R--410A) Refrigerant Charging . . . . . . . . . . . . . 28  
System Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
Loss of Charge Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
Check Defrost Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . 28  
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
START--UP CHECKLIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
SAFETY CONSIDERATIONS  
Installation and servicing of this equipment can be hazardous due  
to mechanical and electrical components. Only trained and  
qualified personnel should install, repair, or service this equipment.  
Untrained personnel can perform basic maintenance functions such  
as cleaning and replacing air filters. All other operations must be  
performed by trained service personnel. When working on this  
equipment, observe precautions in the literature, on tags, and on  
labels attached to or shipped with the unit and other safety  
precautions that may apply.  
Follow all safety codes. Wear safety glasses, protective clothing,  
and work gloves. Use quenching cloth for brazing operations.  
Have  
a
fire extinguisher available. Read these instructions  
thoroughly and follow all warnings or cautions included in  
literature and attached to the unit. Consult local building codes, the  
current editions of the National Electrical Code (NEC) NFPA 70.  
In Canada refer to the current editions of the Canadian Electrical  
Code CSA C22.1.  
1
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A09410  
Fig. 2 -- 50VT--A24--30 Unit Dimensions  
3
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A09411  
Fig. 3 -- 50VT--A36--60 Unit Dimensions  
4
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Dashed lines show cross support  
location for large basepan units.  
B
G
C
HVAC unit  
basepan  
HVAC unit  
base rails  
Sealing  
Gasket  
Roofcurb  
H
F
A
Anchor screw  
Wood nailer*  
Roofcurb*  
Flashing field  
supplied  
Insulation  
(field supplied)  
Roofing material  
field supplied  
E
D
Cant strip  
field supplied  
A09413  
SMALL/COMMON CURB  
*Provided with roofcurb  
A09090  
ROOF CURB DETAIL  
B
C
SMALL  
BASE  
UNIT  
SUPPLY  
AIR  
G
H
A
LARGE  
BASE  
UNIT  
F
RETURN  
AIR  
E
D
UNIT PLACEMENT ON  
COMMON CURB  
A09094  
A09415  
SMALL OR LARGE BASE UNIT  
LARGE CURB  
A09414  
Fig. 4 -- Roof Curb Dimensions  
A
B (small/common  
C
F
UNIT  
SIZE  
CATALOG  
NUMBER  
B (large base)  
IN. (mm)*  
D
E
G
H
IN.  
base)  
IN.  
IN.  
IN. (mm)  
IN. (mm)  
IN. (mm)  
IN. (mm)  
(mm)  
IN. (mm)*  
(mm)  
(mm)  
Small  
or  
CPRFCURB010A00 11 (279)  
10 (254)  
14 (356)  
32.4 (822)  
30.6 (778)  
CPRFCURB011A00 14 (356)  
CPRFCURB012A00 11 (279)  
CPRFCURB013A00 14 (356)  
Large  
14 (356)  
16 (406) 47.8 (1214)  
2.7 (69)  
46.1 (1170)  
Large  
43.9 (1116)  
42.2 (1072)  
* Part Numbers CPRCURB010A00 and CPRCURB011A00 can be used on both small and large basepan units. The cross supports must be located based on  
whether the unit is a small basepan or a large basepan.  
NOTES:  
1. Roof curb must be set up for unit being installed.  
2. Seal strip must be applied, as required, to unit being installed.  
3. Roof curb is made of 16---gauge steel.  
4. Attach ductwork to curb (flanges of duct rest on curb).  
5. Insulated panels: 1---in. (25 mm) thick fiberglass 1 lb. density.  
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CAUTION - NOTICE TO RIGGERS  
PRUDENCE - AVIS AUX MANIPULATEUR  
ACCESS PANELS MUST BE IN PLACE WHEN RIGGING.  
PANNEAUX D'ACCES DOIT ÊTRE EN PLACE POUR MANIPULATION.  
Use top skid as spreader bar. / Utiliser la palette du haut comme barre de répartition  
DUCTS  
MINIMUM HEIGHT: 36" (914.4 mm)  
HAUTEUR MINIMUM  
BANDE SCELLANT DOIT ÊTRE  
EN PLACE AVANT DE PLACER  
L'UNITÉ SUR LA BASE DE TOIT  
SEAL STRIP MUST BE IN  
PLACE BEFORE PLACING  
UNIT ON ROOF CURB  
UNIT HEIGHT  
HAUTEUR D'UNITÉ  
DETAIL A  
VOIR DÉTAIL A  
SEE DETAIL A  
VOIR DÉTAIL A  
50CY502286 2.0  
A09051  
RIGGING WEIGHTS (SMALL CABINET)  
RIGGING WEIGHTS (LARGE CABINET)  
36* 42* 48*  
24  
30  
60*  
Unit  
Unit  
lb  
kg  
lb  
kg  
lb  
kg  
lb  
kg  
lb  
kg  
lb  
kg  
Rigging  
Weight  
Rigging  
Weight  
354  
161  
346  
157  
426  
193  
472  
214  
460  
209  
506  
230  
* For 460 volt units, add 14 lb (6.4 kg) to the weight.  
NOTE: See dimensional drawing for corner weight distribution.  
Fig. 5 -- Rigging Weights  
Step 4 — Rig and Place Unit  
Rigging and handling of this equipment can be hazardous for  
many reasons due to the installation location (roofs, elevated  
structures, etc.).  
!
WARNING  
UNIT FALLING HAZARD  
Failure to follow this warning could result in personal  
injury or death.  
Only trained, qualified crane operators and ground support staff  
should handle and install this equipment.  
When working with this equipment, observe precautions in the  
literature, on tags, stickers, and labels attached to the equipment,  
and any other safety precautions that might apply.  
Training for operators of the lifting equipment should include, but  
not be limited to, the following:  
Never stand beneath rigged units or lift over people.  
1. Leave top shipping skid on the unit for use as a spreader bar  
to prevent the rigging straps from damaging the unit. If the  
skid is not available, use a spreader bar of sufficient length  
to protect the unit from damage.  
1. Application of the lifter to the load, and adjustment of the  
lifts to adapt to various sizes or kinds of loads.  
!
WARNING  
2. Instruction in any special operation or precaution.  
PROPERTY DAMAGE HAZARD  
3. Condition of the load as it relates to operation of the lifting  
kit, such as balance, temperature, etc.  
Failure to follow this warning could result in personal injury  
or death.  
Follow all applicable safety codes. Wear safety shoes and work  
gloves.  
When straps are taut, the clevis should be a minimum of 36  
in. (914 mm) above the unit top cover.  
Inspection  
Prior to initial use, and at monthly intervals, all rigging shackles,  
clevis pins, and straps should be visually inspected for any damage,  
evidence of wear, structural deformation, or cracks. Particular  
attention should be paid to excessive wear at hoist hooking points  
and load support areas. Materials showing any kind of wear in  
these areas must not be used and should be discarded.  
Rigging/Lifting of Unit (See Fig. 5)  
Lifting holes are provided in base rails as shown.  
1. Attach shackles, clevis pins, and straps to the base rails of  
the unit. Be sure materials are rated to hold the weight of the  
unit (See Fig. 5).  
2. Attach a clevis of sufficient strength in the middle of the  
straps. Adjust the clevis location to ensure unit is lifted level  
with the ground.  
After the unit is placed on the roof curb or mounting pad, remove  
the top skid.  
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CONFIGURING UNITS FOR DOWNFLOW  
(VERTICAL) DISCHARGE  
Step 5 — Select and Install Ductwork  
The design and installation of the duct system must be in  
accordance with the standards of the NFPA for installation of  
non--residence type air conditioning and ventilating systems,  
NFPA 90A or residence--type, NFPA 90B and/or local codes and  
ordinances.  
!
WARNING  
ELECTRICAL SHOCK HAZARD  
Failure to follow this warning could result in personal  
injury or death.  
Select and size ductwork, supply--air registers, and return air grilles  
according to ASHRAE (American Society of Heating,  
Refrigeration, and Air Conditioning Engineers) recommendations.  
Before performing service or maintenance operations on the  
system, turn off main power to unit and install lockout tag.  
There may be more than one disconnect switch.  
The unit has duct flanges on the supply-- and return--air openings  
on the side of the unit.  
1. Open all electrical disconnects and install lockout tag before  
starting any service work.  
2. Remove horizontal (metal) ductcovers to access vertical  
(downflow) discharge duct knockouts in unit basepan. (See  
Fig. 6.)  
!
WARNING  
PERSONAL INJURY HAZARD  
Failure to follow this warning could result in personal  
injury or death.  
3. To remove downflow return and supply knockout covers,  
For vertical supply and return units, tools or parts could  
drop into ductwork Install a 90 degree turn in the return  
ductwork between the unit and the conditioned space. If a  
90 degree elbow cannot be installed, then a grille of  
sufficient strength and density should be installed to  
prevent objects from falling into the conditioned space.  
Units with electric heaters require 90 degree elbow in  
supply duct.  
break front and right side connecting tabs with  
a
screwdriver and hammer. Push cover down to break rear  
and left side tabs.  
When designing and installing ductwork, consider the following:  
1. All units should have field--supplied filters or accessory  
filter rack installed in the return--air side of the unit.  
Recommended sizes for filters are shown in Table 1.  
2. Avoid abrupt duct size increases and reductions. Abrupt  
change in duct size adversely affects air performance.  
IMPORTANT: Use flexible connectors between ductwork and  
unit to prevent transmission of vibration. Use suitable gaskets to  
ensure weather tight and airtight seal. When electric heat is  
installed, use fireproof canvas (or similar heat resistant material)  
connector between ductwork and unit discharge connection. If  
flexible duct is used, insert a sheet metal sleeve inside duct. Heat  
resistant duct connector (or sheet metal sleeve) must extend 24--in.  
(610 mm) from electric heater element.  
Horizontal Duct Covers  
A09076  
Basepan  
Downflow  
(Vertical)  
Supply  
Knockout  
Basepan  
Downflow  
(Vertical)  
Return  
3. Size ductwork for cooling air quantity (cfm). The minimum  
air quantity for proper electric heater operation is listed in  
Table 2. Heater limit switches may trip at air quantities  
below those recommended.  
Knockout  
A09093  
4. Seal, insulate, and weatherproof all external ductwork. Seal,  
insulate and cover with a vapor barrier all ductwork passing  
through conditioned spaces. Follow latest Sheet Metal and  
Air Conditioning Contractors National Association  
(SMACNA) and Air Conditioning Contractors Association  
(ACCA) minimum installation standards for residential  
heating and air conditioning systems.  
5. Secure all ducts to building structure. Flash, weatherproof,  
and vibration--isolate duct openings in wall or roof  
according to good construction practices.  
Fig. 6 -- Supply and Return Duct Opening  
NOTE: These panels are held in place with tabs similar to an  
electrical knockout. Reinstall horizontal duct covers (Fig. 6)  
shipped on unit from factory. Insure openings are air and  
watertight.  
NOTE: The design and installation of the duct system must be in  
accordance with the standards of the NFPA for installation of  
nonresidence--type air conditioning and ventilating systems, NFPA  
90A or residence--type, NFPA 90B; and/or local codes and  
ordinances.  
Adhere to the following criteria when selecting, sizing, and  
installing the duct system:  
1. Units are shipped for side shot installation.  
2. Select and size ductwork, supply--air registers, and  
return--air grilles according to American Society of Heating,  
Refrigeration and Air Conditioning Engineers (ASHRAE)  
recommendations.  
3. Use flexible transition between rigid ductwork and unit to  
prevent transmission of vibration. The transition may be  
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screwed or bolted to duct flanges. Use suitable gaskets to  
ensure weather--tight and airtight seal.  
4. All units must have field--supplied filters or accessory filter  
rack installed in the return--air side of the unit.  
Recommended sizes for filters are shown in Table 1.  
5. Size all ductwork for maximum required airflow (either  
heating or cooling) for unit being installed. Avoid abrupt  
duct size increases or decreases or performance may be  
affected.  
least 1 in. (25 mm) every 10 ft (3 m) of horizontal run. Be sure to  
check the drain trough for leaks. Prime the trap at the beginning of  
the cooling season start--up.  
TRAP  
OUTLET  
1-in. (25 mm) min.  
2-in. (51 mm) min.  
6. Adequately insulate and weatherproof all ductwork located  
outdoors. Insulate ducts passing through unconditioned  
space, and use vapor barrier in accordance with latest issue  
of Sheet Metal and Air Conditioning Contractors National  
Association (SMACNA) and Air Conditioning Contractors  
of America (ACCA) minimum installation standards for  
heating and air conditioning systems. Secure all ducts to  
building structure.  
A09052  
Fig. 9 -- Condensate Trap  
Step 7 — Install Electrical Connections  
!
CAUTION  
UNIT COMPONENT DAMAGE HAZARD  
7. Flash, weatherproof, and vibration--isolate all openings in  
building structure in accordance with local codes and good  
building practices.  
Failure to follow this caution may result in damage to the unit  
being installed.  
1. Make all electrical connections in accordance with NEC  
NFPA 70 (latest edition) and local electrical codes  
governing such wiring. In Canada, all electrical  
connections must be in accordance with CSA standard  
C22.1 Canadian Electrical Code Part 1 and applicable  
local codes. Refer to unit wiring diagram.  
2. Use only copper conductor for connections between  
field--supplied electrical disconnect switch and unit. DO  
NOT USE ALUMINUM WIRE.  
A
C
MAXIMUM ALLOWABLE  
DIFFERENCE in. (mm)  
B
B-C  
(6.35)  
A-B  
(6.35)  
A-C  
(6.35)  
1/4  
1/4  
1/4  
3. Be sure that high--voltage power to unit is within  
operating voltage range indicated on unit rating plate. On  
3--phase units, ensure phases are balanced within 2  
percent. Consult local power company for correction of  
improper voltage and/or phase imbalance.  
A07925  
Fig. 7 -- Unit Leveling Tolerances  
OPTIONAL  
RETURN  
AIR  
OPTIONAL  
SUPPLY  
AIR  
OPENING  
OPENING  
4. Do not damage internal components when drilling  
through any panel to mount electrical hardware, conduit,  
etc.  
2˝  
(50.8mm)  
!
WARNING  
EVAP. COIL  
COND. COIL  
ELECTRICAL SHOCK HAZARD  
A07926  
Failure to follow this warning could result in personal injury  
or death.  
Fig. 8 -- Slab Mounting Detail  
Step 6 — Provide for Condensate Disposal  
NOTE: Ensure that condensate--water disposal methods comply  
with local codes, restrictions, and practices.  
The unit cabinet must have an uninterrupted, unbroken  
electrical ground. This ground may consist of an electrical  
wire connected to the unit ground screw in the control  
compartment, or conduit approved for electrical ground when  
installed in accordance with NEC,NFPA 70 National Fire  
Protection Association (latest edition) (in Canada, Canadian  
Electrical Code CSA C22.1) and local electrical codes.  
The 50VT--A units dispose of condensate through a 3/4 in. NPT  
female fitting that exits on the compressor end of the unit.  
Condensate water can be drained directly onto the roof in rooftop  
installations (where permitted) or onto a gravel apron in ground  
level installations. Install a field--supplied condensate trap at end of  
condensate connection to ensure proper drainage. Make sure that  
the outlet of the trap is at least 1 in. (25 mm) lower than the  
drain--pan condensate connection to prevent the pan from  
overflowing. Prime the trap with water. When using a gravel apron,  
make sure it slopes away from the unit.  
High-Voltage Connections  
The unit must have  
a
separate electrical service with  
a
field--supplied, waterproof disconnect switch mounted at, or within  
sight from the unit. Refer to the unit rating plate, NEC and local  
codes for maximum fuse/circuit breaker size and minimum circuit  
amps (ampacity) for wire sizing.  
If the installation requires draining the condensate water away from  
the unit, install a field--supplied 2 --in. (51mm) trap at the  
condensate connection to ensure proper drainage. Condensate trap  
is available as an accessory or is field--supplied. Make sure that the  
outlet of the trap is at least 1 in. (25 mm) lower than the unit  
drain--pan condensate connection to prevent the pan from  
The field--supplied disconnect may be mounted on the unit over  
the high--voltage inlet hole when the standard power and  
low--voltage entry points are used. See Fig. 2 and 3 for acceptable  
location. Remove high voltage knockout.  
See unit wiring label (Fig. 12--14) and Fig. 10 for reference when  
making high voltage connections. Proceed as follows to complete  
the high--voltage connections to the unit.  
overflowing. Connect  
a
drain tube using  
a
minimum of  
field--supplied 3/4--in. PVC or field--supplied 3/4--in. copper pipe  
at outlet end of the 2--in. (51 mm) trap. (See Fig. 9) Do not  
undersize the tube. Pitch the drain tube downward at a slope of at  
8
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control voltage wires), use no. 16 AWG color--coded, insulated  
(35° C minimum) wires.  
HIGH VOLTAGE  
POWER LEADS  
(SEE UNIT WIRING  
LABEL)  
POWER  
SUPPLY  
Standard Connections  
Locate the eight (nine on 3--phase) low voltage thermostat leads in  
24 volt splice box. See Fig. 10 for connection diagram. Run the  
low--voltage leads from the thermostat, through the control wiring  
inlet hole grommet (Fig. 2 and 3), and into the low--voltage splice  
box. Provide a drip loop before running wires through panel.  
Secure and strain relief all wires so that they do not interfere with  
operation of unit. A gray wire is standard on 3--phase units for  
connection to an economizer.  
3-PHASE SHOWN  
1-PHASE USES  
TWO POWER  
EQUIP GR  
LEADS  
FIELD-SUPPLIED  
FUSED DISCONNECT  
CONTROL BOX  
WHT(W1)  
W1  
W2  
Y
VIO (W2)  
YEL(Y)  
GRN(G)  
If an accessory electric heater is installed, low voltage leads from  
heater must be connected to factory supplied control leads from  
Indoor Fan Board P4 connector.  
NOTE: If the unit 24V wires do not have a matching receptacle,  
cut the 24V wires from the electric heater plug, strip the ends, and  
wire nut together to match the schematic connections. If the electric  
heater 24V wires do not have a matching plug, cut the 24V wires  
from the unit receptacle, strip the ends, and wire nut together to  
match the schematic connections.  
G
THERMOSTAT  
(TYPICAL)  
LOW-VOLTAGE  
POWER LEADS  
RED(R)  
BRN(C)  
R
)
(SEE UNIT  
C
O
WIRING LABEL  
ORN(O)  
BLU(DH)  
GRA(Y2)  
DH  
3-Phase  
Only  
SPLICE BOX  
A09071  
Factory wires are provided for electric heat staging W1 and W2  
(W2 and W3 on IFB). If room thermostat has only one stage of  
supplemental heat, connect white and violet wires shown in Fig. 10  
to second stage heat field wire.  
Some electric heaters have four control wires (plus common wire).  
Consult unit wiring diagram and electric heater wiring diagram for  
additional details.  
Fig. 10 -- High-- and Control--Voltage Connections  
Single phase units:  
1. Run the high--voltage (L1, L2) and ground lead into the  
control box.  
2. Connect ground lead to chassis ground connection.  
3. Locate the black and yellow wires connected to the line side  
of the contactor.  
4. Connect field L1 to black wire on connection 11 of the  
compressor contactor.  
5. Connect field wire L2 to yellow wire on connection 23 of  
the compressor contactor.  
Transformer Protection  
The transformer is of the energy--limiting type. It is set to withstand  
a 30--second overload or shorted secondary condition. If an  
overload or short is present, correct overload condition and check  
for blown fuse on Interface Fan Board. Replace fuse as required  
with correct size and rating.  
Three--phase units:  
1. Run the high--voltage (L1, L2, L3) and ground lead into the  
control box.  
2. Connect ground lead to chassis ground connection.  
Accessory Electric Heaters Installation  
Electric heaters may be installed with the 50VT--A units per  
instructions supplied with electric heater package. See unit rating  
plate for factory--approved electric heater kits.  
3. Locate the black and yellow wires connected to the line side  
of the contactor.  
Sequence of Operation  
4. Connect field L1 to black wire on connection 11 of the  
compressor contactor.  
5. Connect field wire L3 to yellow wire on connection 13 of  
the compressor contactor.  
a. CONTINUOUS FAN  
(1.) Thermostat closes circuit R to G energizing the  
blower motor for continuous fan.  
b. COOLING MODE  
6. Connect field wire L2 to blue wire from compressor.  
(1.) If indoor temperature is above temperature set  
point, thermostat closes circuits R to G, R to Y and  
R to O--The unit delivers cooling airflow.  
Special Procedures for 208-V Operation  
c. ELECTRIC HEATING MODE  
(1.) Thermostat closes circuit R to W/W1, or W2 and R  
to G. There are no on or off delays.  
!
WARNING  
ELECTRICAL SHOCK HAZARD  
d. HEAT PUMP HEATING MODE  
Failure to follow this warning could result in personal  
injury or death.  
(1.) Thermostat closes circuits R to G and R to Y. The  
compressor, indoor and outdoor fans are energized.  
e. HEAT PUMP HEATING WITH AUXILIARY  
ELECTRIC HEAT  
Before installing or servicing system, always turn off main  
power to system. Tag the disconnect switch with a suitable  
warning label. With disconnect switch open, move black  
wire from transformer (3/16 in.) terminal marked 230 to  
terminal marked 208. This retaps transformer to primary  
voltage of 208 vac.  
(1.) Thermostat closes circuits R to G, R to Y and R to  
W/W1 or W2. The compressor, indoor and outdoor  
fans are energized, as well as the electric heat  
relays.  
f. DEFROST MODE  
Control Voltage Connections  
The defrost mode is automatically energized by the  
defrost board during heating mode. The defrost board  
energizes “O” (reversing valve) and “W2” (electric  
heat). It also de--energizes the outdoor fan. When defrost  
is complete, unit will return to heating mode. If room  
thermostat is satisfied during defrost, unit will shut  
down and restart in defrost on next call for heat.  
NOTE: Do not use any type of power--stealing thermostat. Unit  
control problems may result.  
Use no. 18 American Wire Gage (AWG) color--coded, insulated  
(35°C minimum) wires to make the control voltage connections  
between the thermostat and the unit. If the thermostat is located  
more than 100 ft (30.5 m) from the unit (as measured along the  
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Table 1 – Physical Data -- Unit 50VT--A  
50VT-A24  
50VT-A30  
2.5  
50VT-A36  
50VT-A42  
3.5  
50VT-A48  
50VT-A60  
Unit Size  
2
3
4
5
Shipping Weight (lb)  
(kg)  
354  
161  
346  
426  
193  
472  
460  
209  
506  
230  
157  
214  
Compressor Quantity  
Type  
1
Scroll  
Refrigerant  
R-410A  
Refrigerant Quantity (lb)  
Quantity (kg)  
11.1  
5.0  
10.3  
4.7  
9.9  
4.5  
11.3  
5.1  
12.5  
5.7  
15.2  
6.9  
Refrigerant Metering Device  
Orifice OD (in)  
(mm)  
Indoor TXV, Outdoor Dual Accuraters  
0.032 (2)  
0.81 (2)  
0.037 (2)  
0.94 (2)  
0.038 (2)  
0.97 (2)  
0.040 (2)  
1.02 (2)  
0.040 (2)  
1.02 (2)  
0.049 (2)  
1.24 (2)  
Outdoor Coil  
Rows...Fins/in,  
face area (sq. ft.)  
Outdoor Fan  
2...21  
13.6  
2...21  
13.6  
2...21  
13.6  
2...21  
17.5  
2...21  
17.5  
2...21  
23.3  
Nominal Airflow (cfm)  
Diameter (in.)  
Diameter (mm)  
Motor hp (rpm)  
Indoor Coil  
2500  
24  
610  
2700  
24  
610  
3100  
26  
660  
3100  
26  
660  
3100  
26  
660  
3500  
26  
660  
1/10 (810)  
1/5 (810)  
1/5 (810)  
1/5 (810)  
1/5 (810)  
1/4 (810)  
Rows...Fins/in,  
face area (sq. ft.)  
Indoor Blower  
Nominal Airflow (cfm)  
Size (in.)  
3...17  
3.7  
3...17  
3.7  
3...17  
4.7  
3...17  
4.7  
3...17  
5.6  
3...17  
5.6  
800  
10 x 10  
254 x 254  
1/2  
1000  
10 x 10  
254 x 254  
1/2  
1200  
11 x 10  
279 x 254  
3/4  
1400  
11 x 10  
279 x 254  
3/4  
1600  
11 x 10  
279 x 254  
1
1750  
11 x 10  
279 x 254  
1
Size (mm)  
Motor hp (rpm)  
High Pressure Switch (psig)  
Cutout  
650 +/- 15  
420 +/- 25  
Reset (Auto)  
Loss-of-Charge/Low Pressure Switch (psig)  
Cutout  
20 +/- 5  
45 +/- 10  
Reset (Auto)  
Return Air Filters  
disposable (in)  
(mm)  
20x20x1  
508x508x25  
20x24x1  
508x610x25  
24x30x1  
610x762x25  
24x36x1  
610x914x25  
*Required filter sizes shown are based on the larger of the AHRI (Air Conditioning Heating and Refrigeration Institute) rated cooling airflow or the heating airflow  
velocity of 300 ft/minute for throwaway type or 450 ft/minute for high---capacity type. Air filter pressure drop for non---standard filters must not exceed 0.08 IN.  
W.C.  
{ If using accessory filter rack refer to the filter rack installation instructions for correct filter size and quantity.  
}
For 460 volt units, add 14 lb (6.4 kg) to the weight.  
Table 2 – Minimum Airflow for Reliable Electric Heater Operation (CFM)  
SIZE  
AIRFLOW (CFM)  
50VT -A24  
50VT -A30  
50VT -A36  
50VT -A42  
50VT -A48  
50VT -A60  
800  
1025  
1250  
1400  
1710  
1800  
INDOOR  
THERMOSTAT  
RETURN  
AIR  
FROM  
TOP COVER  
POWER  
SOURCE  
DISCONNECT  
PER NEC  
POWER ENTRY  
CONTROL ENTRY  
A09098  
Fig. 11 -- Typical Installation  
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A11002  
Fig. 12 -- Connection Wiring Schematics 208/230--1--60  
11  
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A11001  
Fig. 12 Cont. -- Ladder Wiring Schematics 208/230--1--60  
12  
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A11006  
Fig. 13 -- Connection Wiring Schematics -- 208/230--3--60  
13  
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A11005  
Fig. 13 Cont. -- Ladder Wiring Schematics -- 208/230--3--60  
14  
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A10195  
Fig. 14 -- Connection Wiring Diagram 460--3--60  
15  
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A10195  
Fig. 14 Cont. -- Ladder Wiring Diagram 460--3--60  
16  
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high--side Schrader fitting located on the compressor  
discharge line. Be sure that caps on the ports are tight.  
PRE--START--UP  
START--UP  
!
WARNING  
Checking Cooling and Heating Control Operation  
FIRE, EXPLOSION, ELECTRICAL SHOCK AND  
ENVIRONMENTAL HAZARD  
Start and check the unit for proper control operation as follows:  
(1.) Place room thermostat SYSTEM switch or MODE  
control in OFF position. Observe that blower  
motor starts when FAN mode is placed in FAN ON  
position and shuts down when FAN MODE switch  
is placed in AUTO position.  
Failure to follow this warning could result in personal injury,  
death or property damage.  
1. Follow recognized safety practices and wear protective  
goggles when checking or servicing refrigerant system.  
2. Relieve and recover all refrigerant from system before  
touching or disturbing compressor plug if refrigerant  
leak is suspected around compressor terminals.  
3. Do not remove compressor plug until all electrical  
sources are disconnected and tagged.  
4. Never attempt to repair soldered connection while  
refrigerant system is under pressure.  
(2.) Thermostat:  
When the room temperature rises to a point that is  
slightly above the cooling control setting of the  
thermostat, the thermostat completes the circuit  
between thermostat terminal R to terminals Y, O  
and G.These completed circuits through the  
thermostat connect contactor coil (C) (through unit  
wire Y) and Indoor Fan board (through unit wire  
G) across the 24--v. secondary of transformer  
(TRAN).  
5. Do not use torch to remove any component. System  
contains oil and refrigerant under pressure.  
To remove a component, wear protective goggles and  
proceed as follows:  
(3.) Place system switch or MODE control in HEAT  
position. Set control above room temperature.  
Observe that compressor, outdoor fan, and indoor  
blower motors start. Observe that heating cycle  
shuts down when control setting is satisfied.  
(4.) When using an automatic changeover room  
thermostat place both SYSTEM or MODE control  
and FAN mode switches in AUTO positions.  
Observe that unit operates in Cooling mode when  
temperature control is set to “call for Cooling”  
(below room temperature), and unit operates in  
Heating mode when temperature control is set to  
“call for Heating” (above room temperature).  
NOTE: Once the compressor has started and then has stopped, it  
should not be started again until 5 minutes have elapsed. The  
defrost board has a built--in 5 minute delay between cycles. The 5  
minute compressor delay also applies to heat pump heating mode.  
a. Shut off electrical power to unit and install lockout  
tag.  
b. Relieve and reclaim all refrigerant from system  
using both high-- and low--pressure ports.  
c. Cut component connecting tubing with tubing  
cutter and remove component from unit.  
d. Carefully unsweat remaining tubing stubs when  
necessary. Oil can ignite when exposed to torch  
flame.  
Use the Start--Up Checklist supplied at the end of this book and  
proceed as follows to inspect and prepare the unit for initial  
start--up:  
1. Remove all access panels (see Fig. 21).  
2. Read and follow instructions on all DANGER, WARNING,  
CAUTION, and INFORMATION labels attached to, or  
shipped with, unit.  
Step 1 — Check for Refrigerant Leaks  
Proceed as follows to locate and repair a refrigerant leak and to  
charge the unit:  
3. Make the following inspections:  
a. Inspect for shipping and handling damages such as  
broken lines, loose parts, disconnected wires, etc.  
1. Locate leak and make sure that refrigerant system pressure  
has been relieved and reclaimed from both high-- and  
low--pressure ports.  
b. Inspect for oil at all refrigerant tubing connections and  
on unit base. Detecting oil generally indicates a  
refrigerant leak. Leak--test all refrigerant tubing  
connections using electronic leak detector, or  
2. Repair leak following Refrigerant Service procedures.  
NOTE: Install a bi--flow filter drier whenever the system has been  
opened for repair.  
liquid--soap solution. If a refrigerant leak is detected, see  
following Check for Refrigerant Leaks section.  
3. Add a small charge of R--410A refrigerant vapor to system  
and leak--test unit.  
c. Inspect all field and factory--wiring connections. Be sure  
that connections are completed and tight. Ensure wires  
do not touch refrigerant tubing or sharp sheet metal  
edges.  
d. Inspect coil fins. If damaged during shipping and  
handling, carefully straighten fins with a fin comb.  
4. Recover refrigerant from refrigerant system and evacuate to  
500 microns if no additional leaks are not found.  
5. Charge unit with Puron (R--410A) refrigerant, using an  
electronic scale. Refer to unit rating plate for required  
charge.  
Step 2 — Start--Up Adjustments  
4. Verify the following conditions:  
Complete the required procedures given in the Pre--Start--Up  
section before starting the unit. Do not jumper any safety devices  
when operating the unit. Do not operate the unit in Cooling mode  
when the outdoor temperature is below 40_F (4_C) (unless  
accessory low--ambient kit is installed).  
a. Make sure that outdoor--fan blade is correctly positioned  
in fan orifice.  
b. Make sure that air filter(s) is in place.  
c. Make sure that condensate drain pan and trap are filled  
with water to ensure proper drainage.  
d. Make sure that all tools and miscellaneous loose parts  
have been removed.  
IMPORTANT: Three--phase, scroll compressors are direction  
oriented. Unit must be checked to ensure proper compressor  
3--phase power lead orientation. If not corrected within 5 minutes,  
the internal protector will shut off the compressor. The 3--phase  
power leads to the unit must be reversed to correct rotation. When  
5. Each unit system has 2 Schrader--type ports, one low--side  
Schrader fitting located on the suction line, and one  
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turning backwards, the difference between compressor suction and  
discharge pressures may be near zero.  
!
WARNING  
Checking and Adjusting Refrigerant Charge  
The refrigerant system is fully charged with Puron (R--410A)  
refrigerant and is tested and factory sealed.  
ELECTRICAL SHOCK HAZARD  
Failure to follow this warning could result in personal  
injury or death.  
NOTE:  
Adjustment of the refrigerant charge is not required  
Disconnect electrical power to the unit and install lockout  
tag before changing blower speed.  
unless the unit is suspected of not having the proper Puron  
(R--410A) charge.  
A subcooling charging chart is attached to the inside of the  
compressor access panel (see Fig. 21). The chart includes the  
required liquid line temperature at given discharge line pressures  
and outdoor ambient temperatures.  
This unit is factory-set up for use with a single cooling fan speed.  
In addition, this unit has the field-selectable capability to run two  
different cooling fan speeds: The rated cooling fan speed (350~400  
CFM/Ton) and an enhanced dehumidification fan speed (As low as  
320 CFM/Ton) for use with either a dehumidistat or a thermostat  
that supports dehumidification.  
An accurate thermocouple-- or thermistor--type thermometer, and a  
gauge manifold are required when using the subcooling charging  
method for evaluating the unit charge. Do not use mercury or small  
dial--type thermometers because they are not adequate for this type  
of measurement.  
NOTE: Allow system to operate for a minimum of 15 minutes  
before checking or adjusting refrigerant charge.  
The cooling speed is marked “LOW” on the interface fan board  
(IFB) (See Fig. 16) . The factory-shipped settings are noted in  
Table 4. There are 4 additional speed tap wires available for use in  
either electric heating or cooling (For color coding on the indoor  
fan motor leads, see Table 3). The additional 4 speed tap wires are  
shipped loose with vinyl caps and are located in the control box,  
near the interface fan board (IFB) (See Fig. 16).  
IMPORTANT: When evaluating the refrigerant charge, an  
indicated adjustment to the specified factory charge must always be  
very minimal. If a substantial adjustment is indicated, an abnormal  
condition exists somewhere in the cooling system, such as  
insufficient airflow across either coil or both coils.  
Single Cooling Fan Speed Set-up (Dehumidification  
feature not used)  
To change cooling speed:  
Proceed as follows:  
1. Remove the vinyl cap off of the desired speed tap wire  
(Refer to Table 3 for color coding). Add the wet coil  
pressure drop in Table 7 to the system static to determine the  
correct cooling airflow speed in Table 4 that will deliver the  
nominal cooling airflow as listed in Table 1 for each size.  
1. Remove caps from low-- and high--pressure service fittings.  
2. Using hoses with valve core depressors, attach low-- and  
high--pressure gauge hoses to low-- and high--pressure  
service fittings, respectively.  
3. Start unit and let run until system pressures stabilize.  
4. Measure and record the following:  
2. Remove the current speed tap wire from the “LOW”  
terminal on the interface fan board (IFB) (See Fig. 16) and  
place vinyl cap over the connector on the wire.  
3. Connect the desired speed tap wire to the “LOW” terminal  
on the interface fan board (IFB).  
a. Outdoor ambient--air temperature (°F [°C] db).  
b. Liquid line temperature (°F [°C]) at TXV.  
c. Discharge (high--side) pressure (psig).  
NOTE: If accessory electric heat is installed, and the electric heat  
fan speed is chosen to be the same as the normal cooling fan speed,  
the dry airflow must meet or exceed the minimum airflow speed  
specified in Table 2 for the specific size unit.  
d. Suction (low--side) pressure (psig) (for reference only).  
5. Using Cooling Charging Charts compare outdoor--air  
temperature (°F [°C] db) with the discharge line pressure  
(psig) to determine desired system operating liquid line  
temperature (See Fig. 18).  
6. Compare actual liquid line temperature with desired liquid  
line temperature. Using a tolerance of ±2°F (±1.1°C), add  
refrigerant if actual temperature is more than 2°F (1.1°C)  
higher than proper liquid line temperature, or remove  
refrigerant if actual temperature is more than 2°F (1.1°C)  
lower than required liquid line temperature.  
Two Cooling Fan Speeds Set-up (Dehumidification  
feature used)  
IMPORTANT: Dehumidification control must open control  
circuit on humidity rise above set point.  
Use of the dehumidification cooling fan speed requires use of  
either a 24 VAC dehumidistat or a thermostat which includes  
control of a 24 VAC dehumidistat connection. In either case, the  
dehumidification control must open the control circuit on humidity  
rise above the dehumidification set point.  
NOTE:  
If the problem causing the inaccurate readings is a  
refrigerant leak, refer to Check for Refrigerant Leaks section.  
Indoor Airflow and Airflow Adjustments  
1. Using Fig. 16, move the two pin DEHUM jumper from the  
“STD” position to the “DEHUM” position.  
2. Remove fan speed tap wire from the “LOW” terminal on  
the interface fan board (IFB) (See Fig. 16).  
3. Determine correct normal cooling fan speed for unit and  
application. Add the wet coil pressure drop in Table 7 to  
the system static to determine the correct cooling airflow  
speed in Table 4 that will deliver the nominal cooling  
airflow as listed in Table 1 for each size.  
!
CAUTION  
UNIT OPERATION HAZARD  
Failure to follow this caution may result in unit damage.  
For cooling operation, the recommended airflow is 350 to  
450 cfm for each 12,000 Btuh of rated cooling capacity. For  
heating operation, the airflow must produce a temperature  
rise that falls within the range stamped on the unit rating  
plate.  
NOTE: If accessory electric heat is installed, the dry  
airflow must meet or exceed the minimum airflow speed  
specified in Table 2 for the specific size unit. The electric  
heat fan speed will be the same as the normal cooling fan  
speed.  
NOTE: Be sure that all supply--and return--air grilles are open,  
free from obstructions, and adjusted properly.  
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4. Remove the vinyl cap off of the desired speed tap wire  
(Refer to Table 3 for color coding) for the normal cooling  
fan speed and place desired speed tap wire on “HIGH” on  
the interface board.  
!
CAUTION  
UNIT OPERATION HAZARD  
5. Refer to airflow tables (Table 4) to determine allowable  
speeds for the dehumidification cooling fan speed. In Table  
4, speeds that are not allowed for dehumidification cooling  
are shaded.  
Failure to follow this caution may result in unit component  
damage or improper operation.  
To use this mode, a speed connection must be made on the  
“HIGH” terminal that meets or exceeds the minimum  
airflow found in Table 2.  
6. Remove the vinyl cap off of the desired speed tap wire  
(Refer to Table 3 for color coding) for the dehumidification  
cooling fan speed and place desired speed tap wire on the  
“LOW” connection on the interface board (IFB). Verify  
that static pressure is in the acceptable range for the speed  
tap to be used for dehumidification cooling.  
Table 3 – Color Coding for Indoor Fan Motor Leads  
Black = High Speed  
Orange = Med--High Speed  
Red = Med Speed  
Pink = Med--Low Speed  
7. Use any spare vinyl plugs to cap any unused speed tap  
wires.  
Blue = Low Speed  
Single Speed Cooling With Higher Electric Heat Speed  
This unit can also be configured to operate with single speed  
cooling and a higher speed for an accessory electric heater.  
!
WARNING  
1. Move the two pin DEHUM jumper located on control  
board (see Fig. 16) from the “STD” position to the  
“DEHUM” position.  
ELECTRICAL SHOCK HAZARD  
Failure to follow this warning could result in personal  
injury or death.  
2. See Table 2 for minimum airflow for electric heat operation.  
Add electric heater and filter pressure drop to duct system  
static pressure to determine total external static pressure.  
Disconnect electrical power to the unit and install lockout  
tag before changing blower speed.  
3. Select speed tap from Table 4 that will achieve required  
airflow from Table 2.  
Continuous Fan Operation  
When the DEHUM feature is not used, the continuous fan speed  
will be the same as cooling fan speed. When the DEHUM feature  
is used, the continuous fan will operate on IFB “LOW” speed  
when the DH control lead is not energized, or IFB “HIGH” speed  
when the DH lead is energized (see Fig. 16).  
4. Remove the vinyl cap off of the desired speed tap wire  
(Refer to Table 3 for color coding).  
5. Connect the desired speed tap wire to the “HIGH” terminal  
on the interface fan board (IFB).  
INDOOR COIL  
OUTDOOR COIL  
TXV in Metering  
Position  
LCS  
HPS  
Bypass  
Position  
LEGEND  
HPS – High Pressure Switch  
LCS – Loss of Charge Switch  
®
Accurater Metering Device  
Arrow indicates direction of flow  
C03011  
Fig. 15 -- Typical Heat Pump Operation, Cooling Mode  
19  
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HIGH  
QC5  
LOW  
QC4  
COM  
QC3  
KL  
D2  
KZ  
DCR  
QCR  
QC1  
C
R13 C8 R11  
Q1  
07 09 0L0 08  
ALO  
Q3  
AL2  
C9  
RL  
C4  
G1  
G2  
01  
QIL  
Z2 06 04  
A7 R9 AB A15  
F1  
C0  
Z1  
U1  
R4  
RL4  
C3  
D5 D3  
C7  
JWZ  
JW5  
QCB  
R3 R5 R6  
P2 JW3  
R2  
P4  
Y
R
W2  
Y
C
W3 W3 W2 W2  
JW4  
C
SSTZ-8  
P1  
Y2  
DH  
Y1  
Y
W3 W2  
G
C
R
A09059  
Fig. 16 -- Interface Fan Board (IFB)  
INDOOR COIL  
OUTDOOR COIL  
TXV in Bypass  
Position  
LCS  
HPS  
Metering  
Position  
LEGEND  
HPS – High Pressure Switch  
LCS – Loss of Charge Switch  
®
Accurater Metering Device  
Arrow indicates direction of flow  
C03012  
Fig. 17 -- Typical Heat Pump Operation, Heating Mode  
If defrost thermostat is closed, speed--up pins (J1) must be shorted  
by placing a flat head screw driver in between for 5 sec and  
releasing, to observe a complete defrost cycle. When the Quiet  
Shift switch is selected, compressor will be turned off for two 30  
sec intervals during this complete defrost cycle, as explained  
previously. When Quiet Shift switch is in factory default OFF  
position, a normal and complete defrost cycle will be observed.  
Step 3 — Defrost Control  
Quiet Shift  
Quiet Shift is a field--selectable defrost mode, which will eliminate  
occasional noise that could be heard at the start of defrost cycle and  
restarting of heating cycle. It is selected by placing DIP switch 3  
(on defrost board) in ON position.  
When Quiet Shift switch is placed in ON position, and a defrost is  
initiated, the following sequence of operation will occur. Reversing  
valve will energize, outdoor fan will turn off, compressor will turn  
off for 30 sec and then turn back on to complete defrost. At the  
start of heating after conclusion of defrost reversing valve will  
de--energize, compressor will turn off for another 30 sec, and the  
outdoor fan will stay off for 40 sec, before starting in the Heating  
mode.  
If defrost thermostat is in open position, and speedup pins are  
shorted (with a flat head screw driver) for 5 sec and released, a  
short defrost cycle will be observed (actual length is dependent  
upon the selected Quiet Shift position). When Quiet Shift switch is  
in ON position, the length of defrost is 1 minute (30 sec  
compressor off period followed by 30 sec of defrost with  
compressor operation). On return to heating operation, compressor  
will again turn off for an additional 30 sec and the outdoor fan for  
40 sec. When the Quiet Shift is in OFF position, only a brief 30  
sec. cycle will be observed.  
Defrost  
The defrost control is a time/temperature control which includes a  
field--selectable time period (DIP switch 1 and 2 on the board)  
between defrost cycles of 30, 60, 90, or 120 minutes (factory set at  
60 minutes). To initiate a forced defrost, two options are available  
depending on the status of the defrost thermostat.  
NOTE: Unit will remain in defrost until defrost thermostat  
reopens at approximately 65_F (18_C) coil temperature at liquid  
line or remainder of defrost cycle time.  
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Indoor Blower and Motor  
NOTE: All motors are pre--lubricated. Do not attempt to lubricate  
these motors.  
MAINTENANCE  
To ensure continuing high performance, and to minimize the  
possibility of premature equipment failure, periodic maintenance  
must be performed on this equipment. This heat pump unit should  
be inspected at least once each year by a qualified service person.  
To troubleshoot unit, refer to Table 10.  
NOTE: 460 volt units have a stepdown autotransformer that  
supplies approximately 230 volts to a nominal 230 volt indoor  
blower motor.  
NOTE: TO EQUIPMENT OWNER: Consult your local dealer  
about the availability of a maintenance contract.  
For longer life, operating economy, and continuing efficiency,  
clean accumulated dirt and grease from the blower wheel and  
motor annually.  
!
WARNING  
!
WARNING  
PERSONAL INJURY AND UNIT DAMAGE HAZARD  
ELECTRICAL SHOCK HAZARD  
Failure to follow this warning could result in personal injury  
or death and unit component damage.  
Failure to follow this warning could result in personal injury  
or death.  
The ability to properly perform maintenance on this  
equipment requires certain expertise, mechanical skills, tools  
and equipment. If you do not possess these, do not attempt to  
perform any maintenance on this equipment, other than those  
procedures recommended in the Owner’s Manual.  
Disconnect and tag electrical powerto theunit beforecleaning  
the blower motor and wheel.  
To clean the blower motor and wheel:  
1. Remove and disassemble blower assembly as follows:  
a. Remove blower access panel (see Fig 22).  
!
WARNING  
b. Disconnect 5 pin plug and 4 pin plug from indoor  
blower motor. Remove capacitor if required.  
ELECTRICAL SHOCK HAZARD  
c. On all units remove blower assembly from unit.  
Remove screws securing blower to blower partition and  
slide assembly out. Be careful not to tear insulation in  
blower compartment.  
Failure to follow these warnings could result in personal  
injury or death:  
1. Turn off electrical power to the unit and install a lockout  
tag before performing any maintenance or service on this  
unit.  
d. Ensure proper reassembly by marking blower wheel and  
motor in relation to blower housing before disassembly.  
2. Use extreme caution when removing panels and parts.  
e. Loosen setscrew(s) that secures wheel to motor shaft,  
remove screws that secure motor mount brackets to  
housing, and slide motor and motor mount out of  
housing.  
3. Never place anything combustible either on or in contact  
with the unit.  
2. Remove and clean blower wheel as follows:  
a. Ensure proper reassembly by marking wheel orientation.  
!
CAUTION  
b. Lift wheel from housing. When handling and/or  
cleaning blower wheel, be sure not to disturb balance  
weights (clips) on blower wheel vanes.  
UNIT OPERATION HAZARD  
Failure to follow this caution may result in improper  
operation.  
c. Remove caked--on dirt from wheel and housing with a  
brush. Remove lint and/or dirt accumulations from  
wheel and housing with vacuum cleaner, using soft  
brush attachment. Remove grease and oil with mild  
solvent.  
Errors made when reconnecting wires may cause improper  
and dangerous operation. Label all wires prior to  
disconnecting when servicing.  
d. Reassemble wheel into housing.  
The minimum maintenance requirements for this equipment are as  
follows:  
e. Reassemble motor into housing. Be sure setscrews are  
tightened on motor shaft flats and not on round part of  
shaft. Reinstall blower into unit. Reinstall capacitor.  
1. Inspect air filter(s) each month. Clean or replace when  
necessary.  
f. Connect 5 pin plug and 4 pin plug to indoor blower  
motor.  
2. Inspect indoor coil, drain pan, and condensate drain each  
cooling season for cleanliness. Clean when necessary.  
g. Reinstall blower access panel (see Fig. 21).  
3. Inspect blower motor and wheel for cleanliness each  
cooling season. Clean when necessary.  
3. Restore electrical power to unit. Start unit and check for  
proper blower rotation and motor speeds during cooling  
cycles.  
4. Check electrical connections for tightness and controls for  
proper operation each cooling season. Service when  
necessary.  
Step 1 — Air Filter  
IMPORTANT: Never operate the unit without a suitable air filter  
in the return--air duct system. Always replace the filter with the  
same dimensional size and type as originally installed. See Table 1  
for recommended filter sizes.  
Inspect air filter(s) at least once each month and replace  
(throwaway--type) or clean (cleanable--type) at least twice during  
each cooling season and twice during the heating season, or  
whenever the filter becomes clogged with dust and lint.  
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A09412  
Fig. 18 -- Cooling Charging Table--Subcooling  
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Speedup  
Pins  
Quiet  
Shift  
Defrost interval  
DIP switches  
A08020  
Fig. 19 -- Defrost Control  
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If no refrigerant leaks are found and low performance is suspected,  
refer to Checking and Adjusting Refrigerant Charge section.  
Step 2 — Outdoor Coil, Indoor Coil, and  
Condensate Drain Pan  
Inspect the condenser coil, evaporator coil, and condensate drain  
pan at least once each year.  
The coils are easily cleaned when dry; therefore, inspect and clean  
the coils either before or after each cooling season. Remove all  
obstructions, including weeds and shrubs, that interfere with the  
airflow through the condenser coil.  
Straighten bent fins with a fin comb. If coated with dirt or lint,  
clean the coils with a vacuum cleaner, using the soft brush  
attachment. Be careful not to bend the fins. If coated with oil or  
grease, clean the coils with a mild detergent--and--water solution.  
Rinse coils with clear water, using a garden hose. Be careful not to  
splash water on motors, insulation, wiring, or air filter(s). For best  
results, spray condenser coil fins from inside to outside the unit. On  
units with an outer and inner condenser coil, be sure to clean  
between the coils. Be sure to flush all dirt and debris from the unit  
base.  
Step 6 — Indoor Airflow  
The heating and/or cooling airflow does not require checking  
unless improper performance is suspected. If a problem exists, be  
sure that all supply--air and return--air grilles are open and free  
from obstructions, and that the air filter is clean. When necessary,  
refer to Indoor Airflow and Airflow Adjustments section to check  
the system airflow.  
Step 7 — Metering Devices--TXV & Piston  
This unit uses 2 types of metering devices. The outdoor metering  
device is a fixed orifice and is contained in the brass hex--body in  
each liquid line feeding the outdoor coils. The indoor metering  
device is a TXV type device.  
Inspect the drain pan and condensate drain line when inspecting  
the coils. Clean the drain pan and condensate drain by removing all  
foreign matter from the pan. Flush the pan and drain trough with  
clear water. Do not splash water on the insulation, motor, wiring, or  
air filter(s). If the drain tube is restricted, clear it with a plumbers  
snake or similar probe device.  
Step 3 — Outdoor Fan  
Keep the condenser fan free from all obstructions to ensure proper  
cooling operation. Never place articles on top of the unit. Damage  
to unit may result.  
1. Remove 6 screws holding outdoor grille and motor to top  
cover.  
2. Turn motor/grille assembly upside down on top cover to  
expose fan blade.  
3. Inspect the fan blades for cracks or bends.  
4. If fan needs to be removed, loosen setscrew and slide fan off  
motor shaft.  
C99097  
5. When replacing fan blade, position blade back to same posi-  
tion as before.  
Fig. 20 -- Refrigerant Circuit  
6. Ensure that setscrew engages the flat area on the motor shaft  
when tightening.  
7. Replace grille.  
Step 4 — Electrical Controls and Wiring  
Inspect and check the electrical controls and wiring annually. Be  
sure to turn off the electrical power to the unit.  
Remove access panels (see Fig 22) to locate all the electrical  
controls and wiring. Check all electrical connections for tightness.  
Tighten all screw connections. If any discolored or burned  
connections are noticed, disassemble the connection, clean all the  
parts, restrip the wire end and reassemble the connection properly  
and securely.  
After inspecting the electrical controls and wiring, replace all the  
panels. Start the unit, and observe at least one complete cooling  
cycle to ensure proper operation. If discrepancies are observed in  
operating cycle, or if a suspected malfunction has occurred, check  
each electrical component with the proper electrical  
instrumentation. Refer to the unit wiring label when making these  
checkouts.  
Control  
Access  
Panel  
Blower  
Access  
Panel  
Step 5 — Refrigerant Circuit  
Inspect all refrigerant tubing connections and the unit base for oil  
Compressor  
Access Panel  
accumulation annually. Detecting oil generally indicates  
refrigerant leak.  
a
A09214  
Fig. 21 -- Unit Access Panels  
If oil is detected or if low performance is suspected, leak--test all  
refrigerant tubing using an electronic leak detector, or liquid--soap  
solution. If a refrigerant leak is detected, refer to Check for  
Refrigerant Leaks section.  
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Refrigerant  
Step 8 — Pressure Switches  
Pressure switches are protective devices wired into control circuit  
(low voltage). They shut off compressor if abnormally high or low  
pressures are present in the refrigeration circuit. These pressure  
switches are specifically designed to operate with Puron (R--410A)  
systems. R--22 pressure switches must not be used as replacements  
for the Puron (R--410A) system.  
!
WARNING  
PROPERTY HAZARD, PERSONAL INJURY OR  
ENVIRONMENTAL HAZARD  
Failuretofollowthiswarning couldresult in propertydamage  
or personal injury or death.  
Step 9 — Loss of Charge Switch  
This system uses Puron (R--410A) refrigerant which has  
higher operating pressures than R--22 and other refrigerants.  
No other refrigerant may be used in this system. Gauge set,  
hoses, and recoverysystem mustbe designedto handlePuron.  
If you are unsure consult the equipment manufacturer.  
This switch is located on the liquid line and protects against low  
suction pressures caused by such events as loss of charge, low  
airflow across indoor coil, dirty filters, etc. It opens on a pressure  
drop at about 20 psig. If system pressure is above this, switch  
should be closed. To check switch:  
1. Turn off all power to unit.  
2. Disconnect leads on switch.  
Compressor Oil  
The Copeland scroll compressor uses 3MAF POE oil. If additional  
oil is needed, use Uniqema RL32--3MAF. If this oil is not  
available, use Copeland Ultra 32 CC or Mobil Arctic EAL22 CC.  
This oil is extremely hygroscopic, meaning it absorbs water  
readily. POE oils can absorb 15 times as much water as other oils  
designed to HCFC and CFC refrigerants. Take all necessary  
precautions to avoid exposure of the oil to the atmosphere.  
3. Apply ohm meter leads across switch. You should have  
continuity on a good switch.  
NOTE: Because these switches are attached to refrigeration  
system under pressure, it is not advisable to remove this device for  
troubleshooting unless you are reasonably certain that a problem  
exists. If switch must be removed, remove and recover all system  
charge so that pressure gauges read 0 psig. Never open system  
without breaking vacuum with dry nitrogen.  
Servicing Systems on Roofs with Synthetic Materials  
POE (polyolester) compressor lubricants are known to cause long  
term damage to some synthetic roofing materials. Exposure, even if  
immediately cleaned up, may cause embrittlement (leading to  
cracking) to occur in one year or more. When performing any  
service that may risk exposure of compressor oil to the roof, take  
appropriate precautions to protect roofing. Procedures which risk  
oil leakage include, but are not limited to, compressor replacement,  
repairing refrigerant leaks, replacing refrigerant components such  
as filter drier, pressure switch, metering device, coil, accumulator,  
or reversing valve.  
Step 10 — High--Pressure Switch  
The high--pressure switch is located in the discharge line and  
protects against excessive condenser coil pressure. It opens at 650  
psig.  
High pressure may be caused by a dirty outdoor coil, failed fan  
motor, or outdoor air recirculation.  
To check switch:  
1. Turn off all power to unit.  
2. Disconnect leads on switch.  
3. Apply ohm meter leads across switch. You should have  
continuity on a good switch.  
Synthetic Roof Precautionary Procedure  
1. Cover extended roof working area with an impermeable  
polyethylene (plastic) drip cloth or tarp. Cover an  
approximate 10x10 ft (3x3 m) area.  
Step 11 — Copeland Scroll Compressor (Puron  
Refrigerant)  
The compressor used in this product is specifically designed to  
operate with Puron (R--410A) refrigerant and cannot be  
interchanged.  
2. Cover area in front of the unit service panel with a terry  
cloth shop towel to absorb lubricant spills and prevent  
run--offs, and protect drop cloth from tears caused by tools  
or components.  
3. Place terry cloth shop towel inside unit immediately under  
component(s) to be serviced and prevent lubricant run--offs  
through the louvered openings in the unit base.  
!
WARNING  
4. Perform required service.  
EXPLOSION HAZARD  
5. Remove and dispose of any oil contaminated material per  
local codes.  
Failure to follow this warning could result in personal injury,  
death or property damage.  
Liquid Line Filter Drier  
Wear safety glasses and gloves when handling refrigerants.  
Keep torches and other ignition sources away from refrigerant  
and oils.  
The biflow filter drier is specifically designed to operate with  
Puron. Use only factory--authorized components. Filter drier must  
be replaced whenever the refrigerant system is opened. When  
removing a filter drier, use a tubing cutter to cut the drier from the  
system. Do not unsweat a filter drier from the system. Heat from  
unsweating will release moisture and contaminants from drier into  
system.  
The scroll compressor pumps refrigerant throughout the system by  
the interaction of a stationary and an orbiting scroll. The scroll  
compressor has no dynamic suction or discharge valves, and it is  
more tolerant of stresses caused by debris, liquid slugging, and  
flooded starts. The compressor is equipped with an internal  
pressure relief port. The pressure relief port is a safety device,  
designed to protect against extreme high pressure. The relief port  
has an operating range between 550 and 625 psig differential  
pressure.  
Step 12 — Refrigerant System  
This step covers the refrigerant system of the 50VT--A, including  
the compressor oil needed, servicing systems on roofs containing  
synthetic materials, the filter drier and refrigerant charging.  
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The defrost thermostat signals heat pump that conditions are right  
for defrost or that conditions have changed to terminate defrost. It  
is a thermally actuated switch clamped to outdoor coil to sense its  
temperature. Normal temperature range is closed at 32_ 3_F (0  
1.7_C) and open at 65_ 5_F (18 2.8_C).  
NOTE: The defrost thermostat must be located on the liquid side  
of the outdoor coil on the bottom circuit and as close to the coil as  
possible.  
Puron (R-410A) Refrigerant Charging  
Refer to unit information plate and charging chart. Some R--410A  
refrigerant cylinders contain a dip tube to allow liquid refrigerant to  
flow from cylinder in upright position. For cylinders equipped  
with a dip tube, charge Puron units with cylinder in upright  
position and a commercial metering device in manifold hose.  
Charge refrigerant into suction--line.  
Step 13 — System Information  
Loss of Charge Switch  
The loss of charge switch is a protective device wired into control  
circuit (low voltage). It shuts off the compressor if abnormally low  
pressures are present in the refrigeration circuit.  
FEEDER TUBE  
STUB TUBE  
NOTE: Because these switches are attached to refrigeration  
system under pressure, it is not advisable to remove this device for  
troubleshooting unless you are reasonably certain that a problem  
exists. If switch must be removed, remove and recover all system  
charge so that pressure gauges read 0 psig. Never open system  
without breaking vacuum with dry nitrogen.  
DEFROST  
THERMOSTAT  
Check Defrost Thermostat  
The defrost thermostat is usually located on the lowest liquid  
leaving circuit of the left condenser coil (see Fig. 22). The  
thermostat closes at 32_F (0_C) and opens at 65_F (18_C).  
C99029  
Fig. 22 -- Defrost Thermostat  
TROUBLESHOOTING  
Refer to the Cooling and Heating Troubleshooting Chart (Table  
10) for troubleshooting information.  
START--UP CHECKLIST  
Use the Start--Up Checklist.  
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PURONR (R--410A) QUICK REFERENCE GUIDE  
S
Puron refrigerant operates at 50--70 percent higher pressures than R--22. Be sure that servicing equipment and replacement  
components are designed to operate with Puron  
S
S
S
Puron refrigerant cylinders are rose colored.  
Recovery cylinder service pressure rating must be 400 psig, DOT 4BA400 or DOT BW400.  
Puron systems should be charged with liquid refrigerant. Use a commercial type metering device in the manifold hose when  
charging into suction line with compressor operating  
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
Manifold sets should be minimum 700 psig high side and 180 psig low side with 550 psig low--side retard.  
Use hoses with minimum 700 psig service pressure rating.  
Leak detectors should be designed to detect HFC refrigerant.  
Puron, as with other HFCs, is only compatible with POE oils.  
Vacuum pumps will not remove moisture from oil.  
Do not use liquid--line filter driers with rated working pressures less than 600 psig.  
Do not leave Puron suction line filter driers in line longer than 72 hours.  
Do not install a suction--line filter drier in liquid line.  
POE oils absorb moisture rapidly. Do not expose oil to atmosphere.  
POE oils may cause damage to certain plastics and roofing materials.  
Wrap all filter driers and service valves with wet cloth when brazing.  
A factory approved liquid--line filter drier is required on every unit.  
Do NOT use an R--22 TXV.  
Never open system to atmosphere while it is under a vacuum.  
When system must be opened for service, recover refrigerant, evacuate then break vacuum with dry nitrogen and replace filter  
driers. Evacuate to 500 microns prior to recharging.  
S
S
S
Do not vent Puron into the atmosphere.  
Observe all warnings, cautions, and bold text.  
All indoor coils must be installed with a hard shutoff Puron TXV metering device.  
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Table 10 – Troubleshooting Chart  
SYMPTOM  
CAUSE  
REMEDY  
Call power company  
Power failure  
Fuse blown or circuit breaker tripped  
Replace fuse or reset circuit breaker  
Defective contactor, transformer, or high--pressure,  
loss--of--charge or low--pressure switch  
Replace component  
Compressor and condenser fan will not start.  
Insufficient line voltage  
Incorrect or faulty wiring  
Determine cause and correct  
Check wiring diagram and rewire correctly  
Lower thermostat setting below room tempera-  
ture  
Thermostat setting too high  
Faulty wiring or loose connections in compressor cir-  
cuit  
Check wiring and repair or replace  
Compressor motor burned out, seized, or  
internal overload open  
Defective run/start capacitor, overload, start relay  
Determine cause  
Replace compressor  
Determine cause and replace  
Compressor will not start but condenser fan  
runs  
Replace fuse or reset circuit breaker  
Determine cause  
One leg of 3--phase power dead  
Three--phase scroll compressor  
makes excessive noise, and there may be a  
low pressure differential.  
Correct the direction of rotation by reversing the  
3--phase power leads to the unit.  
Scroll compressor is rotating in the wrong direction  
Refrigerant overcharge or undercharge  
Recover refrigerant, evacuate system, and re-  
charge to capacities shown on rating plate  
Defective compressor  
Insufficient line voltage  
Blocked condenser  
Defective run/start capacitor, overload or start relay  
Defective thermostat  
Replace and determine cause  
Determine cause and correct  
Determine cause and correct  
Determine cause and replace  
Replace thermostat  
Compressor cycles (other than normally sat-  
isfying thermostat).  
Faulty condenser--fan motor or capacitor  
Restriction in refrigerant system  
Dirty air filter  
Replace  
Locate restriction and remove  
Replace filter  
Unit undersized for load  
Thermostat set too low  
Decrease load or increase unit size  
Reset thermostat  
Low refrigerant charge  
Mechanical damage in compressor  
Locate leak, repair, and recharge  
Replace compressor  
Compressor operates continuously  
Recover refrigerant, evacuate system, and re-  
charge  
Air in system  
Condenser coil dirty or restricted  
Dirty air filter  
Clean coil or remove restriction  
Replace filter  
Dirty condenser coil  
Clean coil  
Refrigerant overcharged  
Recover excess refrigerant  
Recover refrigerant, evacuate system, and re-  
charge  
Excessive head pressure  
Air in system  
Condenser air restricted or air short--cycling  
Low refrigerant charge  
Compressor IPR leaking  
Restriction in liquid tube  
High heat load  
Compressor IPR leaking  
Refrigerant overcharged  
Dirty air filter  
Determine cause and correct  
Check for leaks, repair, and recharge.  
Replace compressor  
Remove restriction  
Check for source and eliminate  
Replace compressor  
Head pressure too low  
Excessive suction pressure  
Recover excess refrigerant  
Replace filter  
Low refrigerant charge  
Metering device or low side restricted  
Check for leaks, repair and recharge  
Remove source of restriction  
Increase air quantity  
Check filter–replace if necessary  
Insufficient evaporator airflow  
Suction pressure too low  
Temperature too low in conditioned area  
Outdoor ambient below 55°F (12.7°C)  
Filter drier restricted  
Reset thermostat  
Install low--ambient kit  
Replace filter  
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START--UP CHECKLIST  
(Remove and Store in Job Files)  
I. PRELIMINARY INFORMATION  
MODEL NO.:  
SERIAL NO.:  
DATE:  
TECHNICIAN:  
II. PRESTART--UP (Insert check mark in box as each item is completed)  
( ) VERIFY THAT ALL PACKING MATERIALS HAVE BEEN REMOVED FROM UNIT  
( ) REMOVE ALL SHIPPING HOLD DOWN BOLTS AND BRACKETS PER INSTALLATION INSTRUCTIONS  
( ) CHECK ALL ELECTRICAL CONNECTIONS AND TERMINALS FOR TIGHTNESS  
( ) CHECK THAT INDOOR (EVAPORATOR) AIR FILTER IS CLEAN AND IN PLACE  
( ) VERIFY THAT UNIT INSTALLATION IS LEVEL  
( ) CHECK FAN WHEEL, AND PROPELLER FOR LOCATION IN HOUSING/ORIFICE AND SETSCREW TIGHTNESS  
III. START--UP  
ELECTRICAL  
SUPPLY VOLTAGE  
COMPRESSOR AMPS  
INDOOR (EVAPORATOR) FAN AMPS  
TEMPERATURES  
OUTDOOR (CONDENSER) AIR TEMPERATURE  
RETURN--AIR TEMPERATURE  
DB  
DB  
WB  
COOLING SUPPLY AIR  
DB  
WB  
HEAT PUMP SUPPLY AIR _____________________  
ELECTRIC HEAT SUPPLY AIR _____________  
PRESSURES  
REFRIGERANT SUCTION  
PSIG, SUCTION LINE TEMP*  
REFRIGERANT DISCHARGE  
PSIG, LIQUID TEMP{  
( ) VERIFY REFRIGERANT CHARGE USING CHARGING CHARTS  
* Measured at suction inlet to compressor  
{
Measured at liquid line leaving condenser.  
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Catalog No: 50VT---09SI  
Copyright 2011 Carrier Corp. S 7310 W. Morris St. S Indianapolis, IN 46231  
Edition Date: 01/11  
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.  
Replaces: 50VT---08SI  
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