INSTALLATION AND MAINTENANCE INSTRUCTIONS
4HP16LT Series
Split System Heat Pump
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WARNING
The equipment covered in this manual is to be installed by trained and experienced service
and installation technicians. Improper installation, modification, service, or use can cause
electrical shock, fire, explosion, or other conditions which may cause personal injury, death,
or property damage. Use appropriate safety gear including safety glasses and gloves when
installing this equipment.
WARNING
TABLE OF CONTENTS
Risk of electrical shock. Disconnect all remote
INSTALLATION ...................................... 2
CONNECTION DIAGRAM ..................... 4
START-UP............................................ 13
OPERATION ........................................ 18
MAINTENANCE ................................... 23
power supplies before installing or servicing
any portion of the system. Failure to
disconnect power supplies can result in
property damage, personal injury, or death.
WARNING
Installation and servicing of air conditioning
equipment can be hazardous due to internal
refrigerant pressure and live electrical
components. Only trained and qualified service
personnel should install or service this
equipment. Installation and service performed
by unqualified persons can result in property
damage, personal injury, or death.
Manufactured By
Allied Air Enterprises, Inc.
A Lennox International Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
WARNING
*506468-01*
Sharp metal edges can cause injury. When
installing the unit, use care to avoid sharp
edges.
506468-01
Issue 1004
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Page 1
NOTE: Elevation of the unit may be accomplished by
constructing a frame using suitable materials. If a
support frame is constructed, it must not block drain
holes in unit base.
Refer to the furnace or blower coil Installation Instructions
for additional wiring application diagrams and refer to unit
rating plate for minimum circuit ampacity and maximum
overcurrent protection size.
•
•
When installed in areas where low ambient tempera-
tures exist, locate unit so winter prevailing winds do
not blow directly into outdoor coil.
1. Install line voltage power supply to unit from a properly
sized disconnect switch. Any excess high voltage field
wiring should be trimmed or secured away from the
low voltage field wiring.
Locate unit away from overhanging roof lines which would
allow water or ice to drop on, or in front of, coil or into unit.
2. Ground unit at unit disconnect switch or to an earth
ground. To facilitate conduit, a hole is in the bottom of the
control box. Connect conduit to the control box using a
proper conduit fitting. Units are approved for use only with
copper conductors. 24V Class II circuit connections are
made in the low voltage junction box. Acomplete unit
wiring diagram is located inside the unit control box cover
(see also page 26 of this instruction).
Slab Mounting
When installing a unit at grade level, install on level slab
high enough above grade so that water from higher ground
will not collect around the unit (see Figure 2).
3. Install room thermostat on an inside wall that is not
subject to drafts, direct sunshine, or other heat sources.
Slab Mounting
Discharge Air
4. Install low voltage wiring from outdoor to indoor unit
and from thermostat to indoor unit (see Figure 3 on
page 4).
Building
Structure
5. Do not bundle any excess 24V control wire inside control
box. Run control wire through installed wire tie and tighten
wire tie to provide low voltage strain relief and to maintain
separation of field-installed low and high voltage circuits.
Mounting Slab
Ground Level
WARNING
Line voltage is present at all components
when unit is not in operation on units with
single pole contactors. Disconnect all remote
electric power supplies before opening access
panel. Unit may have multiple power supplies.
Failure to disconnect all power supplies could
result in personal injury or death.
Figure 2
Roof Mounting
Install unit at a minimum of 6" above surface of the roof to
avoid ice buildup around the unit. Locate the unit above a
load bearing wall or area of the roof that can adequately
support the unit. Consult local codes for rooftop applications.
Refrigerant Piping
Electrical Wiring
WARNING
All field wiring must be done in accordance with the
National Electrical Code (NEC) recommendations,
Canadian Electrical Code (CEC) and CSA Standards, or
local codes, where applicable.
Refrigerant can be harmful if inhaled. Refrigerant
must always be used and recovered responsibly.
Incorrect or irresponsible use of refrigerant can
result in personal injury or death.
WARNING
If the 4HP16LT unit is being installed with a new indoor
coil and line set, the refrigerant connections should be
made as outlined in this section. If an existing line set and/
or indoor coil will be used to complete the system, refer to
Unit must be grounded in accordance with
national and local codes. Failure to ground unit
properly can result in personal injury or death.
506468-01
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Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor coil
(flare or sweat connections).
Thermostat Designations
(Some connections may not apply. Refer to
specific thermostat and indoor unit.)
Without Auxiliary Heat
Select line set diameters from Table 2 to ensure that oil
returns to the compressor. Size vertical suction riser to
maintain minimum velocity at minimum capacity.
Recommended line length is 50’ or less. If more than 50’
line set is required, contact Technical Services.
Table 2 shows the diameters for line sets up to 100’ although
vertical lift applications and trapping requirements need to
be reviewed with Technical Services for line sets over 50’.
Refrigerant Line Set Diameters (in.)
Liquid Line
Line S et Length and S ize
B T UH
12 f t. 25 ft. 50 ft. 75 ft. 10 0 f t.
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
1/2
1/2
3/8
1/2
1/2
1/2
24,000
36,000
48,000
60,000
S uction Line
Line S et Length and S ize
B T UH
12 f t. 25 ft. 50 ft. 75 ft. 10 0 f t.
7/8
7/8
3/4
7/8
7/8
3/4
7/8
24,000
36,000
48,000
7/8
7/8
7/8
Do not connect C (common) connection between indoor unit and
thermostat except when required by the indoor thermostat. Refer to
thermostat installation instructions. C (common) connection between
indoor unit and outdoor unit required for proper operation.
1-1/8
1-1/8
7/8
1-1/8
7/8
1-1/8 1-1/8
60,000 1-1/8
1-1/8
1-1/8
Figure 3
For installations exceeding 50’, contact
Technical Services.
this sesction as well as the section that follows entitled
Flushing Existing Line Set and Indoor Coil.
Table 2
If this unit is being matched with an approved line set or
indoor coil which was previously charged with R-22
refrigerand, the line set and coil must be flushed prior to
installation. If the unit is being used with an exisitng indoor
coil which was equipped with a liquid line which served as a
metering device (RFCI), the liquid line must be replaced prior
to the installation of the 4HP16LT unit.
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506468-01
Line Set Isolation
WARNING
Illustrations on pages 6 and 7 demonstrate procedures
which ensure proper refrigerant line set isolation. Figure 5
shows how to install line sets on horizontal runs. Figure 6
shows how to make a transition from horizontal to vertical.
Figure 7 shows how to install line sets on vertical runs.
Polyol ester (POE) oils used with R410A
refrigerant absorb moisture very quickly. It is
very important that the refrigerant system be
kept closed as much as possible. DO NOT
remove line set caps or service valve stub
caps until ready to make connections.
Brazing Connection Procedure
1. Cut ends of refrigerant lines square (free from nicks
or dents). Debur the ends. The pipe must remain
round; do not pinch end of line.
Installing Refrigerant Line
During the installation of an air conditioning system, it is
important to properly isolate the refrigerant line to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling, or floor) may cause objectionable noise
when vibration is translated into sound. As a result, more
energy or vibration can be expected. Close attention to
line set isolation must be observed.
2. Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent
oxidation and the introduction of moisture into the system.
3. Use silver alloy brazing rods (5% or 6% silver alloy for
copper-to-copper brazing or 45% silver alloy for
copper-to-brass or copper-to-steel brazing) which are
rated for use with R410A refrigerant.
Following are some points to consider when placing and
installing a high-efficiency outdoor unit:
4. Remove the Schrader core assemblies before brazing
to protect them from damage due to extreme heat.
Replace the cores when brazing is complete.
Placement
Be aware that some localities are adopting sound ordinances
based on how noisy the unit is at the neighbor’s home, not at
the original installation. Install the unit as far as possible from
the property line. When possible, do not install the unit
directly outside a bedroom window. Glass has a very high
level of sound transmission. Figure 4 shows how to place the
outdoor unit and line set to reduce line set vibration.
5. Remove light maroon washers from service valves and
shield light maroon stickers to protect them during
brazing. Wrap a wet cloth around the valve body and
copper tube stub to protect it from heat damage.
6. Braze the line set to the service valve. Quench the joints
with water or a wet cloth to prevent heat damage to the
valve core and opening port. The tube end must stay
bottomed in the fitting during final assembly to
ensure proper seating, sealing, and rigidity.
Outside Unit Placement
and Installation
7. Install a thermal expansion valve (which is sold
separately and which is approved for use with R410A
refrigerant) in the liquid line at the indoor coil (see
Refrigerant Metering Device on page 9).
Install unit away
from windows
Two 90° elbows installed in lineset
will reduce lineset vibration
Figure 4
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Refrigerant Line Sets: Installing Horizontal Runs
To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.
Wire Tie
(around vapor line only)
8’
Strapping Material
(around vapor line only)
Floor Joist or
Roof Rafter
Tape or Wire Tie
8’
Strap the vapor line to the joist or rafter
at 8’ intervals then strap the liquid line
to the vapor line.
Metal Sleeve
Floor Joist or Roof Rafter
Tape or Wire Tie
Figure 5
Refrigerant Line Sets: Transition from Vertical to Horizontal
Automotive
Muffler-Type
Hanger
Anchored
Heavy Nylon
Wire Tie
Strap Liquid
Line to Vapor
Line
Strap Liquid
Line to Vapor
Line
Wall
Stud
Wall
Stud
Liquid Line
Liquid Line
Vapor Line – Wrapped
Vapor Line – Wrapped
Metal Sleeve
in Armaflex
Metal Sleeve
in Armaflex
Figure 6
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Refrigerant Line Sets: Installing Vertical Runs (new construction shown)
IMPORTANT: Refrigerant
lines must not contact wall.
Outside Wall
Vapor Line
Liquid Line
NOTE: Similar installation practices
should be used if line set is to be
installed on exterior of outside wall.
Wood Block
Between Studs
Wire Tie
Inside Wall
Strap
Sleeve
Vapor Line Wrapped
with Armaflex
Wire Tie
Liquid Line
Outside Wall
Wood Block
IMPORTANT:
Refrigerant
lines must not
contact structure.
Wire Tie
Strap
Caulk
Fiberglass
PVC Pipe
Insulation
Sleeve
Figure 7
Flushing Existing Line Set and Indoor Coil
with a “pump down” feature, and two sets of gauges (one
for use with R22 and one for use with R410A).
This procedure should not be performed on systems
which contain contaminants, such as compressor
burn out.
Flushing Procedure
IMPORTANT: The line set and/or indoor coil must be
flushed with at least the same amount of refrigerant that
previously charged the system. Check the charge in the
flushing cylinder before flushing the unit.
CAUTION
When flushing existing line set and/or indoor
coil, be sure to empty all existing traps. Residual
mineral oil can act as an insulator, preventing
proper heat transfer. It can also clog the thermal
expansion valve, reducing system performance
and capacity. Failure to properly flush system as
explained in these instructions will void warranty.
1. Remove existing R22 refrigerant using the appropriate
procedure.
If the existing outdoor unit is not equipped with shutoff
valves, or if the unit is not operational AND the existing
R22 refrigerant will be used to flush the system:
Disconnect all power to the existing outdoor unit.
Connect the existing unit, a clean recovery cylinder, and
the recovery machine according to the instructions
provided with the recovery machine. Remove all R22
refrigerant from the existing system. Refer to the
gauges after shutdown to confirm that the entire system
is completely void of refrigerant. Disconnect the liquid
and suction lines from the existing outdoor unit.
Required Equipment
The following equipment is needed to flush the existing
line set and indoor coil (see Figure 8 on page 8): Two
clean R22 recovery bottles, an oil-less recovery machine
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Flushing Connections
Note: The inverted R22 cylinder must contain
at least the same amount of refrigerant
as was recovered from the existing
system.
Figure 8
If the existing outdoor unit is equipped with manual
shutoff valves AND new R22 refrigerant will be used
to flush the system:
are not approved for use with R410A refrigerant and
may prevent proper flushing. Use a field-provided
fitting to reconnect the lines.
Start the existing R22 refrigerant system in cooling mode
and close the liquid line valve. Pump all the existing R22
refrigerant back into the outdoor unit.
5. Remove the pressure tap valve cores from the
4HP16LT unit’s service valves. Connect an R-22
cylinder with clean refrigerant to the suction service
valve. Connect the R-22 gauge set to the liquid line
valve and connect a recovery machine with an empty
recovery tank to the gauge set.
(It may be necessary to bypass the low pressure
switches to ensure complete refrigerant evacuation.)
When the low side system pressures reach 0 psig, close
the suction line valve. Disconnect all power to the
existing outdoor unit. Refer to the gauges after shutdown
to confirm that the valves are not allowing refrigerant to
flow back into the low side of the system. Disconnect the
liquid and suction lines from the existing outdoor unit.
6. Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to
allow the recovery machine to pull a vacuum on the
existing system line set and indoor coil.
7. Invert the cylinder of clean R-22 and open its valve to
allow liquid refrigerant to flow into the system through
the suction line valve. Allow the refrigerant to pass
from the cylinder and through the line set and the
indoor coil before it enters the recovery machine.
2. Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure
outlined previously on this page to make line set
connections. Do not install the R410A thermal
expansion valve at this time.
8. After all of the liquid refrigerant has been recovered,
switch the recovery machine to vapor recovery so that
all of the R-22 vapor is recovered. Allow the recovery
machine to pull a vacuum on the system.
3. Make low voltage and line voltage connections to the
new outdoor unit. Do not turn on power to the unit or
open the outdoor unit service valves at this time.
NOTE: A single system flush should remove all of the
mineral oil from the existing refrigerant lines and indoor
coil. A second flushing may be done (using clean
refrigerant) if insufficient amounts of mineral oil were
4. Remove the existing R-22 refrigerant flow control
orifice or thermal expansion valve before continuing
with flushing procedures. R-22 flow control devices
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removed during the first flush. After each system flush,
allow the recovery machine to pull a vacuum on the
system at the end of the procedure.
9. Close the valve on the inverted R22 cylinder and the
gauge set valves. Pump the remaining refrigeraant out of
the recovery machine and turn the machine off.
10. Use nitrogen to break the vacuum on the refrigerant
lines and indoor coil before removing the recovery machine,
gauges, and R22 refrigerant drum. Re-install pressure tap
valve cores into the 4HP16LT unit’s service valves.
11. Install a thermal expansion valve approved for use with
R410a refrigerant in the liquid line at the indoor coil.
Refrigerant Metering Device
Figure 9
4HP16LT units are designed for use with TXV systems only.
An R410a system will not operate properly with an R22
metering device.
4. Strap the superheat sensing bulb to the suction header.
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.
If installing an expansion valve on an indoor coil that
previously used a fixed orifice, be sure to remove the existing
fixed orifice. Failure to remove a fixed orifice when installing
an expansion valve to the indoor coil will result in improper
operation and damage to the system.
TXV Data
Manifold Gauge Set
MODEL
PART NUMBER
Manifold guage sets used with systems charged with R410A
refrigerant must be capable of handling the higher system
operating pressures. The gauges should be rated for use
with pressures 1 - 800 on the high side and a low side of 30”
vacuum to 250 psi with dampened speed to 500 psi. Gauge
hoses must be rated for use at up to 800 psi of pressure
with a 4000 psi burst rating.
H4TXV01
H4TXV02
H4TXV03
4HP16LT- 24
4HP16LT - 36
4HP16LT - 48, -60
Table 3
Liquid and Suction Line Service Valves
To install an expansion valve (See Figure 9):
The liquid line and suction line service valves (See Figure
11) and service ports are used for leak teating, evacuation,
charging, and checking charge.
1. Separate the distributor assembly and remove the piston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributor and tighten to 20 - 30 ft. lbs. Use backup wrench
on all wrench flats. Overtightening will crush the teflon
seal and may cause a leak.
Each valve is equipped with a service port which has a
factory-installed Schrader valve. Aservice port cap protects
the Schrader valve from contamination and serves as the
primary leak seal.
2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 - 30 ft. lbs. Use backup wrench on all wrench
flats. Overtightening will crush the teflon seal and may
cause a leak.
To Access the Schrader Port:
1. Remove the service port cap with an adjustable wrench.
2. Connect gauge to the service port.
3. Connect the external equalizer line to the equalizer port
on the suction line and tighten to 8 ft.lbs.
3. When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
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Page 9
Service Valve
Ball Type Service Valve
(Valve Open)
Valve Closed
Stem Cap
Service Port
Insert hex
wrench here
To outdoor coil
Service
Port Cap
To indoor coil
(valve front seated)
Schrader valve open
to line set when valve is
closed (front seated)
Stem Cap
Insert hex
wrench here
Service Port
Use adjustable wrench. To open, rotate stem
counterclockwise 1/4 turn (90°). To close, rotate
stem clockwise 1/4 turn (90°).
To outdoor coil
Figure 11
To indoor coil
Service Port Cap
The ball valve is equipped with a service port with a
factory-installed Schrader valve. A service port cap
protects the Schrader valve from contamination and
serves as the primary seal.
Schrader
Valve
Valve Open
Figure 10
Leak Testing
To Open Liquid or Suction Line Service Valve:
After the line set has been connected to the indoor and
outdoor units, the line set connections and indoor unit
must be checked for leaks.
1. Remove stem cap with an adjustable wrench.
2. Use a service wrench with a hex-head extension to back
the stem out counterclockwise as far as it will go. Use a
3/16" hex head extension for liquid line service valves
and a 5/16" extension for suction line service valves.
WARNING
Fire, Explosion, and Personal Safety Hazard.
3. Replace the stem cap. Tighten finger tight, then
tighten an additional 1/6 turn.
Failure to follow this warning could result in
damage, personal injury, or death.
To Close Liquid or Suction Line Service Valve:
Never use oxygen to pressurize or purge
refrigeration lines. Oxygen, when exposed to
a spark or open flame, can cause damage by
fire and/or an explosion, that could result in
personal injury or death.
1. Remove the stem cap with an adjustable wrench.
2. Use a service wrench with a hex-head extension to turn
the stem clockwise to seat the valve. Tighten firmly.
3. Replace the stem cap. Tighten finger tight, then
tighten an additional 1/6 turn.
Using an Electronic Leak Detector
Suction Line (Ball Type) Service Valve
1. Connect the high pressure hose of the manifold
gauge set to the suction valve service port. (Normally
the high pressure hose is connected to the liquid line
port; however, connecting it to the suction ports helps
Suction line (ball type) service valves function the same
way as the other valves; the difference is in the construc-
tion (see Figure 11).
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to protect the manifold gauge set from damage
caused by high pressure.)
•
•
Low pressure gauge to suction line service valve
High pressure gauge to liquid line service valve
2. With both manifold valves closed, connect the cylin-
der of R410A refrigerant. Open the valve on the
R410A cylinder (vapor only).
2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to
the center port of the manifold gauge set.
3. Open the high pressure side of the manifold to allow
R410A into the line set and indoor unit. Weigh in a
trace amount of R410A. (A trace amount is a maxi-
mum of 2 oz. of refrigerant or 3 lbs. pressure.) Close
the valve on the R410A cylinder and the valve on the
high pressure side of the manifold gauge set. Discon-
nect the R410A cylinder.
4. Open both manifold valves and start vacuum pump.
5. Evacuate the line set and indoor unit to a minimum of
500 microns or lower. During the early stages of
evacuation, it is desirable to close the manifold gauge
valve at least once to determine if there is a rapid rise
in pressure. A rapid rise in pressure indicates a
relatively large leak. If this occurs, the leak testing
procedure must be repeated.
4. Connect a cylinder of nitrogen with a pressure regulat-
ing valve to the center port of the manifold gauge set.
When using high pressure gas such as nitrogen
for this purpose, be sure to use a regulator that
can control the pressure down to 1 or 2 psig.
6. When 500 microns or lower is maintained, close the
manifold gauge valves, turn off the vacuum pump, and
disconnect the manifold gauge center port hose from
the vacuum pump. Attach the manifold gauge center
port hose to a nitrogen cylinder with pressure regulator
set to 150 psig and purge the hose. Open the manifold
gauge valves to break the vacuum in the line set and
indoor unit. Close the manifold gauge valves.
5. Adjust nitrogen pressure to 150 psig. Open the valve
on the high side of the manifold gauge set to pressur-
ize the line set and the indoor coil.
6. After a short period of time, open a refrigerant port to
make sure that an adequate amount of refrigerant has
been added for detection (refrigerant requirements will
vary with lengths). Check all joints for leaks. Purge
nitrogen and R410A mixture. Correct any leaks and
recheck.
7. Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold
gauge valves to release the nitrogen from the line set
and indoor unit.
Evacuation
8. Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line
set and indoor unit until 500 microns is maintained
within a 20-minute period after shutting off the
Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerant to produce substances that corrode copper
piping and compressor parts.
vacuum pump and closing the manifold gauge valves.
9. When the requirements above have been met,
disconnect the manifold hose from the vacuum pump.
Open the service valves to break the vacuum in the
line set and indoor unit.
WARNING
Do not use a compressor to evacuate a sys-
tem. Avoid deep vacuum operation. Extremely
low vacuums can cause internal arcing and
compressor failure. Danger of equipment
damage. Damage caused by deep vacuum
operation will void warranty.
Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument that
reads down to 50 microns.
1. Connect the manifold gauge set to the service valve
ports as follows:
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Units are factory charged with the amount of R410A
refrigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with 15’
line set. For varying lengths of line set, refer to Table 4 for
refrigerant charge adjustment. A blank space is provided
on the unit rating plate to list the actual field charge.
START-UP
CAUTION
If unit is equipped with a crankcase heater, it should be
energized 24 hours before unit start-up to prevent
compressor damage as a result of slugging.
Refrigerant Charge Adjustment
Liquid Line Set Diameter
Oz. Per 5 ft. adjust from 15
ft. line set*
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and field-installed wiring for loose
connections.
3/8 in.
3 oz. Per 5 ft.
* If line length is greater than 15 ft., add this amount.
If line length is less than 15 ft., remove this amount.
3. After evacuation is complete, open liquid line and suction
line service valves to release refrigerant charge (contained
in outdoor unit) into system.
Table 4
IMPORTANT
4. Replace the stem caps and secure finger tight, then
tighten an additional 1/6 of a turn.
Mineral oils are not compatible with R410A. If oil must
be added, it must be a polyolester oil.
5. Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit nameplate.
If not, do not start equipment until the power company has
been consulted and the voltage condition corrected.
If the system is void of refrigerant, clean the system using
the procedure described below.
1. Use dry nitrogen to pressurized the system and check
for leaks. Repair leaks, if possible.
6. Set thermostat for cooling demand, turn on power to
indoor blower, and close the outdoor unit disconnect switch
to start the unit.
2. Evacuate the system to remove as much of the moisture
as possible.
7. Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate.
3. Use dry nitrogen to break the vacuum.
4. Evacuate the system again.
Refrigerant Charging
This system is charged with R410A refrigerant which
operates at much higher pressures than R-22. The liquid
line drier provided with the unit is approved for use with
R410A. Do not replace it with one designed for use with R-
22. This unit is NOT approved for use with coils which
use capillary tubes as a refrigerant metering device.
5. Weigh the appropriate amount of R410Arefrigerant (listed
on unit nameplate) into the system.
6. Monitor the system to determine the amount of moisture
remaining in the oil. Use a test kit to verify that the moisture
content is withing the kit’s dry color range. It may be
necessary to replace the filter drier several times to achieve
the required dryness level. If system dryness is not
verified, the compressor will fail in the future.
R410A refrigerant cylinders are rose colored.
Refrigerant should be added through the suction valve
in the liquid state.
The outdoor unit should be charged during warm weather.
However, applications arise in which charging must occur in
the colder months. The method of charging is determined
by the unit’s refrigerant metering device and the outdoor
ambient temperature.
Certain R410Acylinders are identified as being equipped
with a dip tube. These allow liquid refrigerant to be
drawn from the bottom of the cylinder without inverting
the cylinder. Do not turn this type of cylinder upside
down to draw refrigerant.
Measure the liquid line temperature and the outdoor ambient
temperature as outlined below:
1. Connect the manifold gauge set to the service valve ports
as follows (See Figure 13 above):
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Page 12
Cooling Cycle
OUTDOOR UNIT
DEFROST THERMOSTAT
EXPANSION/CHECK VALVE
DISTRIBUTOR
NOTE - ARROWS INDICATE
DIRECTION OF
REFRIGERANT FLOW
REVERSING VALVE
OUTDOOR COIL
BIFLOW
FILTER / DRIER
LOW
PRESSURE
HIGH
PRESSURE
INDOOR UNIT
MUFFLER
GAUGE MANIFOLD
SUCTION
SERVICE
PORT
SUCTION
LINE
VALVE
TO
R410A
DRUM
LIQUID
LINE
SERVICE
PORT
COMPRESSOR
INDOOR
COIL
EXPANSION/CHECK VALVE
Use gauge ports on suction line valve and liquid line valve for evacuating refrigerant lines and indoor coil. Use
suction gauge port to measure suction pressure during charging.
Figure 12
•
•
Low pressure gauge to suction line service valve
High pressure gauge to liquid line service valve
3. Weigh in the charge according to the total amount
shown on the unit nameplate.
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R410A.
If weighing facilities are not available, use one of the
following procedures to charge the unit.
3. If room temperature is below 70°F, set the room thermo-
stat to call for heat. This will create the necessary load
for properly charging the system in the cooling cycle.
Charge Using Subcooling Method –
Outdoor Temperatures Below 65°F
When the outdoor ambient temperature is below 65°F, the
subcooling method can be used to charge the unit. It may
be necessary to restrict the air flow through the outdoor
coil to achieve pressures in the 200-250 psig range.
These higher pressures are necessary for checking the
charge. Block equal sections of air intake panels and
move obstructions sideways until the liquid pressure is in
the 200-250 psig range (see Figure 13 on page 14).
4. Use a digital thermometer to record the outdoor
ambient temperature.
5. When the heating demand has been satisfied, switch
the thermostat to cooling mode with a set point of 68°F.
When pressures have stabilized, use a digital thermom-
eter to record the liquid and suction line temperatures.
6. The outdoor temperature will determine which charg-
ing method to use. Proceed with the appropriate
charging method.
1. With the manifold gauge hose still on the liquid
service port and the unit operating stably, use a digital
thermometer to check the liquid line temperature. For
best results, use the same digital thermometer to
check both the outdoor ambient and the liquid line
temperatures.
Charge Using Weigh-In Method
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, first locate and repair any leaks then
use the weigh-in method to charge the unit.
2. At the same time, record the liquid line pressure reading.
3. Use the temperature/pressure chart (Table 5 on page 14)
to determine the saturation temperature for the liquid line
pressure reading.
1. Recover the refrigerant from the unit.
2. Conduct a leak check, then evacuate as previously
outlined.
506468-01
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Blocking Outdoor Coil
Outdoor coil should be
R410A Temperature/Pressure Chart
Temp.
EF
Pressure
Psig
Temp.
EF
Pressure
Psig
Temp.
EF
Pressure
Psig
blocked one side at a time
with cardboard or plastic
sheet until proper testing
pressures are reached.
32
33
100.8
102.9
74
75
214.0
217.4
116
117
396.0
401.3
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
105.0
107.1
109.2
111.4
113.6
115.8
118.0
120.3
122.6
125.0
127.3
129.7
132.2
134.6
137.1
139.6
142.2
144.8
147.4
150.1
152.8
155.5
158.2
161.0
163.9
166.7
169.6
172.6
175.5
178.5
181.6
184.3
187.7
190.9
194.1
197.3
200.6
203.9
207.2
210.6
76
77
220.9
224.4
228.0
231.6
235.3
239.0
242.7
246.5
250.3
254.1
258.0
262.0
266.0
270.0
274.1
278.2
282.3
286.5
290.3
295.1
299.4
303.8
308.2
312.7
317.2
321.8
326.4
331.0
335.7
340.5
345.3
350.1
355.0
360.0
365.0
370.0
375.1
380.2
385.4
390.7
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
406.7
412.2
417.7
423.2
428.8
434.5
440.2
445.9
451.8
457.6
463.5
469.5
475.6
481.6
487.8
494.0
500.2
506.5
512.9
519.3
525.8
532.4
539.0
545.6
552.3
559.1
565.9
572.8
579.8
586.8
593.8
601.0
608.1
615.4
622.7
630.1
637.5
645.0
78
CARDBOARD OR
PLASTIC SHEET
79
80
81
82
83
Figure 13
84
85
4. Subtract the liquid line temperature from the saturation
temperature (according to the chart) to determine
Subcooling.
86
87
88
°
°
°
Saturation Temperature °F
Liquid Line Temperature °F
Subcooling Value °F
89
_
90
=
91
92
5. Compare the subcooling value with those shown in Table
6. If subcooling is greater than shown, recover some
refrigerant. If subcooling is less than shown, add some
refrigerant.
93
94
95
96
97
98
Subcooling Values
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
Table 6
Charge UsingApproach Method (TXV System) - Outdoor
Temperatures 65°F or Above
The following procedure is intended as a general guide and
is for use on expansion valve systems only. For best results,
indoor temperature should be 70°F to 80°F. Monitor system
pressures while charging.
1. Record outdoor ambient temperature usig a digital
thermometer.
72
73
207.2
210.6
114
115
385.4
390.7
2. Attach high pressure gauge set and operate unit for
several minutes to allow system pressures to stabilize.
Table 5
3. Compare stabilized pressures with those provided in Table
7. Minor variations in these pressures may be expected
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Page 14
Normal Operating Pressures
Heating & Cooling
Cooling Indoor: 80 db; 67 wb
Heating (indoor): 70°F
± 2 psi
L - Liquid
S- Suction
Values provided above are for HSV match pressures; different indoor unit match, and indoor load will cause
pressures to vary.
Table 7
system is undercharged. Verify adjusted charge using the
approach method.
due to differences in installations. Significant
differences could mean that the system is not
properly charged or that a problem exists with some
component in the system. Pressures higher than those
listed indicate that the system is overcharged. Pressures
4. Use the same digital thermometer to check liquid line
temperature.
lower than those listed indicate that the
506468-01
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5. Subtract the outdoor ambient temperature from the liquid
line temperture to determine the approach temperature.
Check Charge Using Normal Operating Pressures
Use Table 7 to perform maintenance checks. Table 7 is not
a procedure for charging the system. Minor variations in
these pressures may be due to differences in installations.
Significant deviations could mean that the system is not
properly charged or that a problem exists with some
component in the system.
°
°
°
Liquid Line Temperature °F
Outdoor Ambient Temperature °F
Approach Temperature °F
_
=
6. Compare the approach value with those shown in Table
8. If the values do not agree with those provided in Table 8,
add refrigerant to lower the approach temperature or recover
refrigerant from the system to increase the approach
temperature.
Approach Values for TXV Systems
Approach value is the liquid line temperature minus the outdoor
ambient temperature (±1°F).
Note: For best results, use the same digital thermometer to check
both outdoor ambient and liquid temperatures.
Table 8
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Page 16
NOTE - The demand defrost board accurately
measures the performance of the system as frost
accumulates on the outdoor coil. This typically will
translate into longer running time between defrost
cycles as more frost accumulates on the outdoor coil
before the board initiates defrost cycles.
OPERATION
Outdoor unit and indoor blower cycle on demand from the
room thermostat. When the thermostat blower switch is
moved to the ON position, the indoor blower operates
continuously.
Filter Drier
DIAGNOSTIC LEDS
The unit is equipped with a large capacity bi-flow filter
which keeps the system clean and dry. If replacement is
necessary, replace with one of similar design and
capacity. The replacement filter drier must be suitable for
use with R410A refrigerant.
The state (Off, On, Flashing) of two LEDs on the defrost
board (DS1 [Red] and DS2 [Green]) indicate diagnostics
conditions that are described in table.
Crankcase Heater
If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start-up to prevent
compressor damage as a result of slugging.
Emergency Heat Function (Room Thermostat)
An emergency heat function is designed into some room
thermostats. This feature is applicable when isolation of
outdoor unit is required or when auxiliary electric heat is
stage by outdoor thermostats. When the room thermostat
is placed in the emergency heat position, the outdoor unit
control circuit is isolated from power and the field-supplied
relays bypass the outdoor thermostats. An amber
indicating light simultaneously comes on to remind the
homeowner that the unit is operating in the emergency
heat mode.
Emergency heat is usually used during an outdoor
shutdown, but it should also be used following a power
outage if power has been off for over an hour and the
outdoor temperature is below 50°F. System should be left
in the emergency heat mode at least 6 hours to allow the
crankcase heater sufficient time to prevent compressor
slugging.
Mode
Green Led (DS2)
Red Led (DS1)
OFF
No power to control
OFF
Normal operation/
power to control
Anti-short cycle
lockout
Simultaneous Slow Flash
Alternating Slow Flash
DEMAND DEFROST SYSTEM DESCRIPTION
The demand defrost controller measures differential
temperatures to detect when the system is performing
poorly because of ice build-up on the outdoor coil. The
controller “self-calibrates” when the defrost system starts
and after each system defrost cycle. The defrost control
board components are shown below.
Low pressure switch
fault (Optional)
Slow FLASH
OFF
Low pressure switch
lockout (Optional)
ON
OFF
High presssure switch
fault (Optional)
Slow FLASH
OFF
OFF
High pressure switch
lockout (Optional)
OFF
The control monitors ambient temperature, outdoor
coil temperature, and total run time to determine when a
defrost cycle is required. The coil temperature probe is
designed with a spring clip to allow mounting to the
outside coil tubing. The location of the coil sensor is
important for proper defrost operation.
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Page 17
DEFROST BOARD PRESSURE SWITCH
CONNECTIONS
The unit’s automatic reset pressure switches (LO PS -
S87 and HI PS - S4) are factory-wired into the defrost
board on the LO-PS and HI-PS terminals, respectively.
Sensor Temp. / Resistance Range
Temperature
Range °F (°C)
Pins/Wire
Color
Red Led (DS1)
Sensor
Outdoor
-35 (-37 to 120
(48)
3 & 4
280,000 to 3750
280,000 to 3750
(Ambient)
(Black)
5 & 6
-35 (-37) to 120
(48)
Coil
(Brown)
(OPTIONAL) Low Pressure Switch (LO-PS) — When
the low pressure switch trips, the defrost board will cycle
off the compressor, and the strike counter in the board
will count one strike. The low pressure switch is ignored
under the following conditions:
Discharge (If
applicable)
24 (-4) to 350
(176)
1 & 2
41,000 to 103
(Yellow)
Note: Sensor resistance decreases as sensed temperature increases.
! during the defrost cycle and 90 seconds after the
termination of defrost
! when the average ambient sensor temperature is below
15° F (-9°C)
! for 90 seconds following the start up of the compressor
! during “test” mode
NOTE - When checking the ohms across a sensor, be
aware that a sensor showing a resistance value that
is not within the range shown, may be performing as
designed. However, if a shorted or open circuit is
detected, then the sensor may be faulty and the
sensor harness will needs to be replaced.
High Pressure Switch (HI-PS) — When the high
pressure switch trips, the defrost board will cycle off the
compressor, and the strike counter in the board will count
one strike.
Coil Sensor—The coil temperature sensor considers
outdoor temperatures below -35°F (-37°C) or above
120°F (48°C) as a fault. If the coil temperature sensor is
detected as being open, shorted or out of the temperature
range of the sensor, the board will not perform demand or
time/temperature defrost operation and will display the
appropriate fault code. Heating and cooling operation will
be allowed in this fault condition.
DEFROST BOARD PRESSURE SWITCH SETTINGS
High Pressure (auto reset) - trip at 590 psig; reset at
418.
Low Pressure (auto reset) - trip at 25 psig; reset at 40.
5-STRIKE LOCKOUT FEATURE
The internal control logic of the board counts the pressure
switch trips only while the Y1 (Input) line is active. If a
pressure switch opens and closes four times during a Y1
(Input), the control logic will reset the pressure switch trip
counter to zero at the end of the Y1 (Input). If the
pressure switch opens for a fifth time during the current
Y1 (Input), the control will enter a lockout condition.
Ambient Sensor—The ambient sensor considers
outdoor temperatures below -35°F (-37°C) or above
120°F (48°C) as a fault. If the ambient sensor is detected
as being open, shorted or out of the temperature range of
the sensor, the board will not perform demand defrost
operation. The board will revert to time/temperature
defrost operation and will display the appropriate fault
code. Heating and cooling operation will be allowed in this
fault condition.
The 5-strike pressure switch lockout condition can be
reset by cycling OFF the 24-volt power to the control
board or by shorting the TEST pins between 1 and 2
seconds. All timer functions (run times) will also be reset.
NOTE - Within a single room thermostat
demand, if 5-strikes occur, the board will lockout
the unit. Defrost board 24 volt power “R” must
be cycled “OFF” or the “TEST” pins on board
must be shorted between 1 to 2 seconds to reset
the board.
If a pressure switch opens while the Y1 Out line is
engaged, a 5-minute short cycle will occur after the switch
closes.
DEFROST SYSTEM SENSORS
Sensors connect to the defrost board through a field–
replaceable harness assembly that plugs into the board.
Through the sensors, the board detects outdoor ambient,
coil, and discharge temperature fault conditions. As the
detected temperature changes, the resistance across the
sensor changes. Sensor resistance values can be
checked by ohming across pins .
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Page 18
Defrost Temperature Termination Shunt (Jumper)
Pins—The defrost board selections are: 50, 70, 90, and
100°F (10, 21, 32 and 38°C). The shunt termination pin is
factory set at 50°F (10°C). If the temperature shunt is not
installed, the default termination temperature is 90°F
(32°C).
Actuation—When the reversing valve is de-energized,
the Y1 circuit is energized, and the coil temperature is
below 35°F (2°C), the board logs the compressor run
time. If the board is not calibrated, a defrost cycle will be
initiated after 30 minutes of heating mode compressor run
time. The control will attempt to self-calibrate after this
(and all other) defrost cycle(s).
DELAY MODE
The defrost board has a field-selectable function to
reduce occasional sounds that may occur while the unit is
cycling in and out of the defrost mode. When a jumper is
installed on the DELAY pins, the compressor will be
cycled off for 30 seconds going in and out of the defrost
mode. Units are shipped with jumper installed on DELAY
pins.
Calibration success depends on stable system
temperatures during the 20-minute calibration period. If
the board fails to calibrate, another defrost cycle will be
initiated after 45 minutes of heating mode compressor run
time. Once the defrost board is calibrated, it initiates a
demand def rost cycle when the difference between the
clear coil and frosted coil temperatures exceeds the
maximum difference allowed by the control OR after 6
hours of heating mode compressor run time has been
logged since the last defrost cycle.
NOTE - The 30 second off cycle is NOT functional
when jumpering the TEST pins.
NOTE - If ambient or coil fault is detected, the board
will not execute the “TEST” mode.
OPERATIONAL DESCRIPTION
The defrost control board has three basic operational
modes: normal, calibration, and defrost.
Termination—The defrost cycle ends when the coil
temperature exceeds the termination temperature or after
14 minutes of defrost operation. If the defrost is
terminated by the 14-minute timer, another defrost cycle
will be initiated after 30 minutes of run time.
Normal Mode—The demand defrost board monitors the
O line, to determine the system operating mode (heat/
cool), outdoor ambient temperature, coil temperature
(outdoor coil) and compressor run time to determine
when a defrost cycle is required.
Test Mode—When Y1 is energized and 24V power is
being applied to the board, a test cycle can be initiated by
placing the termination temperature jumper across the
“Test” pins for 2 to 5 seconds. If the jumper remains
across the “Test” pins longer than 5 seconds, the control
will ignore the test pins and revert to normal operation.
The jumper will initiate one cycle per test.
Calibration Mode—The board is considered uncalibrated
when power is applied to the board, after cool mode
operation, or if the coil temperature exceeds the
termination temperature when it is in heat mode.
Calibration of the board occurs after a defrost cycle to
ensure that there is no ice on the coil. During calibration,
the temperature of both the coil and the ambient sensor
are measured to establish the temperature differential
which is required to allow a defrost cycle.
Enter the “TEST” mode by placing a shunt (jumper)
across the “TEST” pins on the board after power-up.
(The “TEST” pins are ignored and the test function is
locked out if the shunt is applied on the “TEST” pins
before power-up). Board timings are reduced, the low-
pressure switch is ignored and the board will clear any
active lockout condition.
Defrost Mode—The following paragraphs provide a
detailed description of the defrost system operation.
DETAILED DEFROST SYSTEM OPERATION
Defrost Cycles—The demand defrost control board
initiates a defrost cycle based on either frost detection or
time.
Each test pin shorting will result in one test event.
For each “TEST” the shunt (jumper) must be removed for
at least 1 second and reapplied. Refer to flow chart for
“TEST” operation.
!
Frost Detection—If the compressor runs longer than
30 minutes and the actual difference between the
clear coil and frosted coil temperatures exceeds the
maximum difference allowed by the control, a defrost
cycle will be initiated.
Note: The Y1 input must be active (ON) and the “O”
room thermostat terminal into board must be
inactive.
IMPORTANT - The demand defrost control board
will allow a greater accumulation of frost and will
initiate fewer defrost cycles than a time/
DEFROST BOARD DIAGNOSTICS
See defrost control board diagnostic LED table on next
page to determine defrost board operational conditions
and to diagnose cause and solution to problems.
temperature defrost system.
!
Time—If 6 hours of heating mode compressor run
time has elapsed since the last defrost cycle while the
coil temperature remains below 35°F (2°C), the
demand defrost control will initiate a defrost cycle.
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Defrost Control Board Diagnostic LEDs
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System Diagnostic Module
flashes correlates to a particular abnormal condition.
TRIP LED (Red) indicates there is a demand signal from
the thermostat but no current to the compressor is de-
tected by the module. The TRIP LED typically indicates
the compressor protector is open or may indicate missing
supply power to the compressor.
4HP16LT units contain a diagnostic module for trouble-
shooting heat pump system failures. By monitoring and
analyzing data from the compressor and thermostat
demand, the module can accurately detect the cause of
electrical and system related failure without any sensors.
If a system problem occurs, a flashing LED indicator
communicates the failure code.
Interpreting the Diagnostic LEDs
When an abnormal system condition occurs, the diagnos-
tic module displays the appropriate ALERT and/or TRIP
LED. The yellow ALERT LED will flash a number of times
consecutively, pause, and then repeat the process. To
identify a flash code number, count the number of con-
secutive flashes. Refer to Table 10 below and Table 11 on
page 20 for information on the flash codes.
LED Description
POWER LED (Green) indicates voltage is present at the
power connection of the module.
ALERT LED (Yellow) communicates an abnormal system
condition through a unique flash code. The ALERT LED
will flash a number of times consecutively, pause, and
then repeat the process. The number of consecutive
Every time the module powers up, the last ALERT LED
flash code that occurred prior to shutdown is displayed for
Flash Codes
LED
Status
Fault Description
Troubleshooting Information
POWER
(Green)
Module has power
Supply voltage is present at module terminals
1. Compressor protector is open
* Check for high head pressure
Thermostat demand
signal Y1 is present,
but the compressor
is not running
* Check compressor supply voltage
TRIP
(Red)
2. Outdoor unit power disconnect is open
3. Compressor circuit breaker or fuse(s) is open
4. Broken wire or connector is not making contact
5. Low pressure switch open if present in system
6. Compressor contactor has failed open
Long Run Time
Compressor is
running
extremely long run
cycles
ALERT
(Yellow)
Flash
--
Code 1
(Not applicable on
heat pump models)
1. High head pressure
* Check high pressure switch if present in system
* Check if system is overcharged with refrigerant
* Check for non-condensable in system
2. Condenser coil poor air circulation (dirty, blocked, damaged)
3. Condenser fan is not running
System
Pressure Trip
Discharge or suction
pressure
ALERT
(Yellow)
Flash
out of limits or
compressor
* Check fan capacitor
* Check fan wiring and connectors
Code 2
overloaded
* Check fan motor for failure or blockage
4. Return air duct has substantial leakage
5. If low pressure switch present in system, check Flash Code 1 info
Table 10
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60 seconds. The module will continue to display the
previous flash code until the condition returns to normal or
24VAC is removed from the module. TRIP and ALERT
LEDs flashing at the same time means control circuit
voltage is too low for operation.
24VAC Power Wiring
The diagnostic module requires a constant nominal
24VAC power supply. The wiring to the module’s R and C
terminals must be directly from the indoor unit or thermo-
stat. The module cannot be powered by R and C terminals
on the defrost board without experiencing nuisance alerts.
Flash Codes (cont.)
LED
Status
Fault Description
Troubleshooting Information
1. Thermostat demand signal is in
2. Time delay relay or control board defective
3. If high pressure switch present, go to Flash Code 2 info
4. If low pressure switch present, go to Flash Code 1 info
termittent
ALERT
(Yellow)
Flash
Short Cycling
Compressor is
running
Code 3
only briefly
1. Run capacitor has failed
ALERT
(Yellow)
Flash
2. Low line voltage (contact utility if voltage at disconnect is low)
* Check wiring connections
3. Excessive liquid refrigerant in compressor
4. Compressor bearings are seized
*Measure compressor oil level
Locked Rotor
Code 4
1. Outdoor unit power disconnect is open
2. Compressor circuit breaker or fuse(s) is open
3. Compressor contactor has failed open
* Check compressor contactor wiring and connectors
* Check for compressor contactor failure (burned, pitted, or open)
* Check wiring and connectors between supply and compressor
* Check for low pilot voltage at compressor contactor coil
4. High pressure switch is open and requires manual reset
5. Open circuit in compressor supply wiring or connections
6. Unusually long compressor protector reset time due to extreme ambient temperature
7. Compressor windings are damaged
ALERT
(Yellow)
Flash
Open Circuit
Code 5
* Check compressor motor winding resistance
1. Run capacitor has failed
ALERT
(Yellow)
Flash
Open Start Circuit
Current only in run
circuit
2. Open circuit in compressor start wiring or connections
* Check wiring and connectors between supply and the compressor S terminal
3. Compressor start winding is damaged
Code 6
* Check compressor motor winding resistance
ALERT
(Yellow)
Flash
1. Open circuit in compressor run wiring or connections
* Check wiring and connectors between supply and the compressor R terminal
2. Compressor run winding is damaged
Open Run Circuit
Current only in start
circuit
Code 7
* Check compressor motor winding resistance
ALERT
(Yellow)
Flash
Welded Contactor
Compressor always
runs
1. Compressor contactor has failed closed
2. Thermostat demand signal not connected to module
Code 8
ALERT
(Yellow)
Flash
Low Voltage
Control circuit less
than 17VAC
1. Control circuit transformer is overloaded
2. Low line voltage (contact utility if voltage at disconnect is low)
* Check wiring conditions
Code 9
Table 11
Page 23
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Thermostat Demand Wiring
Miswired Module Codes
The diagnostic module requires a thermostat demand
signal to operate properly. The thermostat demand signal
input, labeled Y on the module, should always be con-
nected to the compressor contactor coil so that when the
coil is energized, the demand signal input is 24VAC.
When the coil is not energized, the demand signal input
should be less than 0.5VAC.
Depending on the system configuration, some ALERT
flash codes may not be active. The presence of safety
switches affects how the system alerts are displayed by
the module.
Miswiring the diagnostic module will cause false LED
codes. Table 12 describes LED operation when the
module is miswired and what troubleshooting action is
required to correct the problem.
Miswired Module Troubleshooting
Miswired Module Indication
Recommended Troubleshooting Action
Determine if both R and C module terminals are connected. Verify voltage is present
at module's R and C terminals. Review 24VAC Power Wiring section on page 20 for
R and C wiring.
Green LED is not on,
module does not power up.
Green LED intermittent,
module powers up only
when compressor runs.
Determine if R and Y terminals are wired in reverse. Verify module's R and C
terminals have a constant source. Review 24VAC Power Wiring section on page 20
for R and C wiring.
TRIP LED is on but system
and compressor check OK.
Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at contactor
coils falls below 0.5VAC when off.
TRIP LED and ALERT LED
flashing together.
Verify R and C terminals are supplied with 19-28VAC.
ALERT Flash Code 3
(Compressor Short Cycling)
displayed incorrectly.
Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at contactor
coil falls below 0.5VAC when off.
ALERT Flash Code 5, 6, or 7
(Open Circuit, Open Start
Circuit, or Open Run Circuit)
displayed incorrectly.
Check that compressor run and start wires are through module's current sensing
holes. Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at
contactor coil falls below 0.5VAC when off.
ALERT Flash Code 6
(Open Start Circuit)
displayed for Code 7
(Open Run Circuit)
or vice versa.
Check that compressor run and start wires are routed through the correct module
sensing holes.
Determine if module's Y terminal is connected. Verify Y terminal is connected to 24VAC at
contactor coil. Verify 24VAC is present across Y and C when thermostat demand signal is
present. If not, R and C are reverse wired. Verify voltage at contactor coil falls below
0.5VAC when off. Review Thermostat Demand Wiring on this page for Y and C wiring.
ALERT Flash Code 8
(Welded Contactor)
displayed incorrectly.
Table 12
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MAINTENANCE
WARNING
Before performing maintenance operations on
system, turn the electric power to unit OFF at
disconnect switch(es). Unit may have multiple
power supplies. Electrical shock could cause
personal injury or death.
Before the start of each heating and cooling season, the
following service checks should be performed by a
qualified service technician.
•
Inspect and clean outdoor and indoor coils. The
outdoor coil may be flushed with a water hose.
NOTE: It may be necessary to flush the outdoor coil
more frequently if it is exposed to substances which
are corrosive or which block airflow across the coil
(such as pet urine, cottonwood seeds, etc...).
•
•
•
Visually inspect the refrigerant lines and coils for leaks.
Check wiring for loose connections.
Check voltage at the indoor and outdoor units (with
units operating).
•
Check amperage draw at the outdoor fan motor,
compressor, and indoor blower motor. Values should
be compared with those given on unit nameplate.
•
•
Check, clean (or replace) indoor unit filters.
Check the refrigerant charge and gauge the system
pressures.
•
•
•
Check the condensate drain line for free and unob-
structed flow. Clean drain line, if necessary.
Adjust blower speed for cooling. Measure the pressure
drop over the coil to determine the correct blower CFM.
Belt drive blowers: Check drive belt for wear and
proper tensions.
If insufficient cooling is reported, the unit should be
gaugedand refrigerant charge checked (see Refrigerant
Charging on page 12).
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is exposed to substances which are corrosive or
which block airflow across the coil (such as pet urine,
cottonwood seeds, etc...).
HOMEOWNER INFORMATION
In order to ensure peak performance, your system must be
properly maintained. Clogged filters and blocked airflow
prevent your unit from operating at its most efficient level.
Heat Pump Operation
Heat pump units have several characteristics you should
be aware of:
WARNING
Turn all electric power to unit OFF at discon-
nect switch(es) before performing any mainte-
nance operations on system. Unit may have
multiple power supplies. Electrical shock could
cause personal injury or death.
•
•
Heat pumps satisfy heating demand by delivering
large amounts of warm air into the living space. This
is quite different from gas-fired, oil-fired, or electric
furnaces which deliver lower volumes of considerably
hotter air to heat the space.
Do not be alarmed if you notice frost on the outdoor
coil in the winter months. Frost develops on the
outdoor coil during the heating cycle when tempera-
tures are below 45°F. An electronic control activates a
defrost cycle lasting 5 to 15 minutes at preset inter-
vals to clear the outdoor coil of the frost. A shift in
sound type does occur during the defrost mode.
•
Ask your dealer to show you where the indoor unit’s
filter is located. It will be either at the indoor unit
(installed internal or external to the cabinet) or behind
a return air grille in the wall or ceiling. Check the filter
monthly and clean or replace it as needed.
•
•
Disposable filters should be replaced with a filter of
the same type and size. If you unsure of the filter you
need for your system, contact your dealer.
•
During the defrost cycle, you may notice steam rising
from the unit. This is a normal occurrence. The
thermostat may engage auxiliary heat during the
defrost cycle to satisfy a heating demand. The unit will
return to normal operation at the conclusion of the
defrost cycle.
Many indoor units are equipped with reusable foam
filters. These filters can be cleaned with a mild soap
and water solution. Rinse the filter thoroughly and let
dry completely before returning to unit or grille.
In case of extended power outage...
The filter and all access panels must be in place
any time the unit is in operation.
If the outdoor temperature is below 50°F and power to the
outdoor unit has been interrupted for 6 hours or longer,
observe the following when restoring power to the heat
pump system.
•
•
Some systems are equipped with an electronic air
cleaner, designed to remove the majority of airborne
particles from the air passing through the cleaner. If
your system includes an electronic air cleaner, ask
your dealer for maintenance instructions.
•
Set the room thermostat selector to the “Emergency
Heat” setting to obtain temporary heat for a minimum
of 6 hours. This will allow system refrigerant pres-
sures and temperatures enough time to return to a
stabilized condition.
Inspect and clean indoor coil. The indoor evaporator
coil is equipped with a drain pan to collect condensate
formed as the system removes humidity from the
inside air. Have your dealer show you the location of
the drain line and how to check for obstructions. This
also applies to an auxiliary drain, if one is installed.
•
In the Emergency Heat mode, all heating demand is
satisfied by auxiliary heat; heat pump operation is
locked out. After a 6-hour “warmup” period, the
thermostat can then be switched to the “Heat” setting
and normal heat operation may resume.
•
Inspect and clean outdoor coil:
Make sure no obstructions restrict airflow to the
outdoor unit. Leaves, trash, or shrubs crowding the unit
can cause it to work harder and use more energy. Keep
shrubbery trimmed away from the unit and periodically
check for debris which collects around the unit.
Thermostat Operation
Though your thermostat may vary somewhat from the
description below, its operation will be similar.
Temperature Setting Levers
The outdoor coil may require frequent cleaning,
depending on environmental conditions. Clean the
outdoor coil with an unpressurized water hose to
remove surface contaminants and debris. It may be
necessary to flush the outdoor coil more frequently if it
Most heat pump thermostats have two temperature
selector levers: one for heating and one for cooling. Set
the levers or dials to the desired temperature setpoints for
both heating and cooling. Avoid frequent temperature
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adjustment; turning the unit off and back on before
pressures equalize puts stress on unit compressor.
Preservice Check
If your system fails to operate, check the following before
calling for service:
Fan Switch
In AUTO or INT (intermittent) mode, the blower operates
only when the thermostat calls for heating or cooling. This
mode is generally preferred when humidity control is a
priority. The ON or CONT mode provides continuous indoor
blower operation, regardless of whether the compressor or
auxiliary heat are operating. This mode is required when
constant air circulation or filtering is desired.
•
•
Check to see that all electrical disconnect switches
are ON.
Make sure the thermostat temperature selector is
properly set.
•
•
•
•
•
Make sure the thermostat system switch is properly set.
Replace any blown fuses, or reset circuit breakers.
Make sure unit access panels are in place.
Make sure air filter is clean.
System Switch
Set the system switch for heating, cooling, or auto opera-
tion. The auto mode allows the heat pump to automatically
switch from heating mode to cooling mode to maintain
predetermined comfort settings. Many heat pump thermo-
stats are also equipped with an emergency heat mode
which locks out heat pump operation and provides
temporary heat supplied by the auxiliary heat.
Locate unit model number and have it handy before
calling.
Indicating Light
Most heat pump thermostats have an amber light which
indicates when the heat pump is operating in the emer-
gency heat mode.
Temperature Indicator
The temperature indicator displays the actual room
temperature.
Programmable Thermostats
Your system may be controlled by a programmable thermo-
stat. These thermostats provide the added feature of
programmable time-of-day setpoints for both heating and
cooling. Refer to the user’s information manual provided
with your particular thermostat for operation details.
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Start-Up and Performance Checklist
Job Name _______________________________
Job No. ________________
City ___________________
City ___________________
Date ______________
State ______________
State ______________
Job Location _____________________________
Installer _________________________________
Unit Model No.______________
Serial No. ___________________
Service Technician ________________________________________
Nameplate Voltage ______________
Rated Load Ampacity ________
Maximum Fuse or Circuit Breaker________________________
Compressor Amperage ____________ Outdoor Fan ______________
Electrical Connections Tight?
Indoor Filter Clean?
Supply Voltage (Unit Off) ________________
Indoor Blower RPM _____________
S.P. Drop Over Indoor (Dry) ____________
Outdoor Coil Entering Air Temperature _____________
Voltage with Compressor Operating _____________
Outdoor Fan Checked?
Cooling
Liquid Line Pressure __________
Suction Line Pressure ___________ Refrigerant Charge Checked?
Heating
Liquid Line Pressure __________
Suction Line Pressure ___________
Refrigerant Charge Checked?
Refrigerant Lines: Leak Checked?
Service Valves: Fully Opened?
Properly Insulated?
Caps Tight?
Thermostat: Calibrated?
Properly Set?
Level?
Sequence of Operation
Heating Correct?
Cooling Correct?
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Single Stage Wire Diagram
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Two Stage Wire Diagram
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