Armstrong Air 4SHP16LS Series User manual

506860-03 Issue 1946 Page 1 of 27
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INSTALLATION INSTRUCTIONS
4SHP16LS SERIES
Split System Heat Pump
*506860-03*
*506860-03*
Manufactured By
Allied Air Enterprises LLC
A Lennox International, Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
Table of Contents
General........................................................................1
Installation ...................................................................2
Refrigerant Piping........................................................4
Electrical Wiring.........................................................12
Start-Up .....................................................................14
Operation...................................................................15
7-Segment Alert and System Status Codes ..............17
Maintenance..............................................................24
Homeowner Information ............................................24
Wiring Diagrams........................................................26
General
Read this entire instruction manual, as well as the
instructions supplied in separate equipment, before
starting the installation. Observe and follow all warnings,
cautions, instructional labels, and tags. Failure to comply
with these instructions could result in an unsafe condition
and/or premature component failure.
These instructions are intended as a general guide only
for use by qualied personnel and do not supersede any
national or local codes in any way. The installation must
comply with all provincial, state, and local codes as well as
the National Electrical Code (U.S.) or Canadian Electrical
Code (Canada). Compliance should be determined prior
to installation.
This manual must be left with the homeowner for future reference.
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to
the potential for personal injury or death.
Installation and servicing of air conditioning equipment
can be hazardous due to internal refrigerant pressure
and live electrical components. Only trained and
qualied service personnel should install or service
this equipment. Installation and service performed by
unqualied persons can result in property damage,
personal injury, or death.
WARNING
Sharp metal edges can cause injury. When installing
the unit, use care to avoid sharp edges.
WARNING
ELECTRICAL SHOCK HAZARD!
Risk of electrical shock. Disconnect all
remote 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

506860-03Issue 1946Page 2 of 27
This unit uses R-410A, which is an ozone-friendly HFC
refrigerant. The unit must be installed with a matching
indoor coil and line set. A lter drier approved for use with
R-410A is installed in the unit.
IMPORTANT: This product has been designed and
manufactured to meet ENERGY STAR criteria for energy
eciency when matched with appropriate coil components.
However, proper refrigerant charge and proper air ow
are critical to achieve rated capacity and eciency.
Installation of this product should follow the manufacturer’s
refrigerant charging and air ow instructions. Failure to
conrm proper charge and airow may reduce energy
eciency and shorten equipment life.
When servicing or repairing HVAC components, ensure
the fasteners are appropriately tightened. Table 1 shows
torque values for fasteners.
Table 1. Torque Table
Fastener Torque
Stem Caps 8 ft. lbs.
Service Port Caps 8 ft. lbs.
Sheet Metal Screws 16 in. lbs.
#8 Machine Screws 16 in. lbs.
#10 Machine Screws 28 in. lbs.
Compressor Bolts 90 in. lbs.
Inspection of Shipment
Upon receipt of equipment, carefully inspect it for possible
shipping damage. If damage is found, it should be noted
on the carrier’s freight bill. Take special care to examine
the unit inside the carton if the carton is damaged. Any
concealed damage discovered should be reported to the
last carrier immediately, preferably in writing, and should
include a request for inspection by the carrier’s agent.
If any damages are discovered and reported to the carrier
DO NOT INSTALL THE UNIT, as claim may be denied.
Check the unit rating plate to conrm specications are as
ordered.
Safety Precautions
Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloth for brazing operations.
Have re extinguisher available. Read these instructions
thoroughly and follow all warning or cautions attached to
the unit.
1. Always wear proper personal protection equipment.
2. Always disconnect electrical power before removing
panel or servicing equipment.
3. Keep hands and clothing away from moving parts.
4. Handle refrigerant with caution; refer to proper MSDS
from refrigerant supplier.
5. Use care when lifting, avoid contact with sharp edges.
Installation
NOTE: In some cases, noise in the living area has been
traced to gas pulsations from improper installation of
equipment.
• Locate unit away from windows, patios, decks, etc.
where unit operation sounds may disturb customer.
• Leave some slack between structure and unit to
absorb vibration.
• Place a sound-absorbing material, such as Isomode,
under the unit if it will be installed in a location or
position that will transmit sound or vibration to the
living area or adjacent buildings.
• Install the unit high enough above the ground or roof to
allow adequate drainage of defrost water and prevent
ice buildup.
• In heavy snow areas, do not locate the unit where
drifting snow will occur. The unit base should be
elevated above the depth of average snows.
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.
• When installed in areas where low ambient
temperatures exist, locate unit so winter prevailing
winds do not blow directly into outdoor coil.
• Locate unit away from overhanging roof lines which
would allow water or ice to drop on, or in front of, coil
or into unit.
When outdoor unit is connected to factory-approved indoor
unit, outdoor unit contains system refrigerant charge for
operation with matching indoor unit when connected by 15
ft. of eld-supplied tubing. For proper unit operation, check
refrigerant charge using charging information located on
control box cover.
Outdoor Section
Zoning ordinances may govern the minimum distance the
condensing unit can be installed from the property line.
Install on a Solid, Level Mounting Pad
The outdoor section is to be installed on a solid foundation.
This foundation should extend a minimum of 2” (inches)
beyond the sides of the outdoor section. To reduce the
possibility of noise transmission, the foundation slab
should NOT be in contact with or be an integral part of the
building foundation. See Figure 1.
If conditions or local codes require the unit be attached to
pad or mounting frame, tie down bolts should be used and
secured to unit base pan.

506860-03 Issue 1946 Page 3 of 27
Discharge Air
Mounting Slab
Ground Level
Building
Structure
Mounting slab must slope slightly away from
building, not to exceed 1/4” per foot.
Figure 1. Slab Mounting
Elevate Unit
Accumulation of water and ice in base pan may cause
equipment damage.
CAUTION
Elevate unit per local climate and code requirements to
provide clearance above estimated snowfall level and
ensure adequate drainage of unit. Use snow stand in areas
where prolonged freezing temperatures are encountered.
If conditions or local codes require the unit be attached to
pad or mounting frame, tie down bolts should be used and
fastened through knockouts provided in unit base pan.
Clearance Requirements
When installing, allow su󰀩cient space for airow clearance,
wiring, refrigerant piping, and service. For proper airow,
quiet operation and maximum e󰀩ciency. Position so water,
snow, or ice from roof or eaves cannot fall directly on unit.
Refer to Table 2 for installation clearances.
Location Minimum Clearance
Service box 30”
Top of unit* 48”
Between units 24”
Against wall 6”
* Maximum so󰀩t overhang is 36”.
NOTE: At least one side should be unobstructed by a wall or
other barrier.
Table 2. Clearances
30” around
Control
Box
24”
6”*
NOTE: See Table 2 for specific minimum
clearance guidelines.
Figure 2.
DO LOCATE THE UNIT:
• With proper clearances on sides and top of unit
• On a solid, level foundation or pad (unit must be level
to within ± 1/4 in./ft. per compressor manufacturer
specications)
• To minimize refrigerant line lengths
DO NOT LOCATE THE UNIT:
• On brick, concrete blocks or unstable surfaces
• Near clothes dryer exhaust vents
• Near sleeping area or near windows
• Under eaves where water, snow or ice can fall directly
on the unit
• With clearance less than 2 ft. from a second unit
• With clearance less than 4 ft. on top of unit
Operating Ambient
The minimum outdoor operating ambient in cooling mode
is 55°F, and the maximum outdoor operating ambient in
cooling mode is 125°F. The maximum outdoor operating
ambient in heating mode is 66°F.
Rooftop Installations
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.
If unit cannot be mounted away from prevailing winds, a
wind barrier should be constructed. Due to variation in
installation applications, size and locate barrier according
to the best judgment of the installer.

506860-03Issue 1946Page 4 of 27
Refrigerant Piping
• Use only refrigerant grade copper tubes.
• Split systems may be installed with up to 50 feet of
line set (no more than 20 feet vertical) without special
consideration (see long line set guidelines).
• Ensure that vapor and liquid tube diameters are
appropriate to capacity of unit.
• Run refrigerant tubes as directly as possible by
avoiding unnecessary turns and bends.
• When passing refrigerant tubes through the wall, seal
opening with RTV or other silicon-based caulk.
• Avoid direct tubing contact with water pipes, duct work,
oor joists, wall studs, oors, walls, and any structure.
• Do not suspend refrigerant tubing from joists and
studs with a rigid wire or strap that comes in direct
contact with tubing.
• Ensure that tubing insulation is pliable and completely
surrounds vapor tube.
It is important that no tubing be cut or seals broken until you
are ready to actually make connections to the evaporator
and to the condenser section. DO NOT remove rubber
plugs or copper caps from the tube ends until ready to
make connections at evaporator and condenser. Under no
circumstances leave the lines open to the atmosphere for
any period of time, if so unit requires additional evacuation
to remove moisture.
Table 3. Refrigerant Line Set Diameters (in.)
Model Liquid Line Suction Line
24 3/8 3/4
36 3/8 7/8
48 3/8 7/8
60 3/8 1-1/8
For installations exceeding 50’, refer to long line set guidelines
Be extra careful with sharp bends. Tubing can “kink” very
easily, and if this occurs, the entire tube length will have
to be replaced. Extra care at this time will eliminate future
service problems.
It is recommended that vertical suction risers not be up-
sized. Proper oil return to the compressor should be
maintained with suction gas velocity.
Filter Drier
The lter drier is very important for proper system operation
and reliability. If the drier is shipped loose, it must be
installed by the installer in the eld. Unit warranty will be
void, if the drier is not installed.
Installation of Line Sets
DO NOT fasten liquid or suction lines in direct contact with
the oor or ceiling joist. Use an insulated or suspension
type of hanger. Keep both lines separate, and always
insulate the suction line. Liquid line runs (30 feet or more)
in an attic will require insulation. Route refrigeration line
sets to minimize length.
DO NOT let refrigerant lines come in direct contact with
foundation. When running refrigerant lines through the
foundation or wall, openings should allow for a sound
and vibration absorbing material to be placed or installed
between tubing and foundation. Any gap between
foundation or wall and refrigerant lines should be lled with
a vibration damping material.
If ANY refrigerant tubing is required to be buried by state
or local codes, provide a 6 inch vertical rise at service
valve.
CAUTION

506860-03 Issue 1946 Page 5 of 27
Flushing Line Sets
If the unit will be installed in an existing system that uses
an indoor unit or line sets charged with R-22 refrigerant,
installer must perform the following ushing procedure.
NOTE: Existing system components (including line set
and indoor coil) must be an AHRI match with the unit in
order to fulll unit warranty requirements.
Refrigerant must be reclaimed in accordance with
national and local codes.
WARNING
Do NOT attempt to ush and re-use existing line sets
or indoor coil when the system contains contaminants
(i.e., compressor burn out).
CAUTION
“Clean refrigerant” is any refrigerant in a system that
has not had compressor burnout. If the system has
experienced burnout, it is recommended that the
existing line set and indoor coil be replaced.
NOTE
In lieu of R-410A, an industry-standard ushing agent
may also be used.
NOTE
LOW
HIGH
EXISTING
INDOOR
UNIT
GAUGE
MANIFOLD
CYLINDER CONTAINING
CLEAN R-410A TO BE
USED FOR FLUSHING
(Positioned to deliver liquid
refrigerant)
LIQUID LINE SERVICE
VALVE
INLET
DISCHARGE
TANK
RETURN
CLOSED
OPENED
RECOVER
Y
CYLINDER
RECOVERY MACHINE
NEW
OUTDOOR
UNIT
VAPOR LINE
SER
VICE VALVE
VAPOR
LIQUID
1
A
B
C
D
ACylinder with clean R-410A (positioned to deliver liquid refrigerant) to the
vapor service valve.
BRefrigerant gauge set (low side) to the liquid line valve.
CRefrigerant gauge set center port to inlet on the recovery machine with
an empty recovery tank connected to the gauge set.
DConnect recovery tank to recovery machine per machine instructions.
Figure 3.
1. Connect gauges and equipment as shown in Figure 3.
2. 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 unit coil.
3. Position the cylinder of clean R-410A for delivery of
liquid refrigerant and open its valve to allow liquid
refrigerant to ow into the system through the vapor
line valve. Allow the refrigerant to pass from the
cylinder and through the line set and the indoor unit
coil before it enters the recovery machine.
4. After all of the liquid refrigerant has been recovered,
switch the recovery machine to vapor recovery so
that all of the R-410A vapor is recovered. Allow the
recovery machine to pull the system down to 0.
5. Close the valve on the inverted R-410A drum and the
gauge set valves. Pump the remaining refrigerant out
of the recovery machine and turn the machine o󰀨.

506860-03Issue 1946Page 6 of 27
Refrigerant Piping - Install Indoor Expansion Valve
This outdoor unit is designed for use in systems that include an expansion valve metering device (purchased separately) at
the indoor coil. See the Product Specications for approved expansion valve kit match-ups and application information. The
check expansion valve unit can be installed internal or external to the indoor coil. In applications where an uncased coil is
being installed in a eld-provided plenum, install the check/expansion valve in a manner that will provide access for future
eld service of the expansion valve. Refer to below illustration for reference during installation of expansion valve unit.
1 -Attach the vapor line sensing bulb in the proper
orientation as illustrated to the right using the clamp and
screws provided.
NOTE - Though it is preferred to have the sensing bulb
installed on a horizontal run of the vapor line, installation
on a vertical run of piping is acceptable if necessary.
NOTE - Confirm proper thermal contact between vapor
line and check/expansion bulb before insulating the
sensing bulb once installed.
2 -Connect the equalizer line from the check expansion
valve to the equalizer vapor port on the vapor line. Finger
tighten the flare nut plus 1/8 turn (7 ft-lbs) as illustrated
below.
TWO PIECE
PATCH PLATE
(UNCASED
COIL ONLY)
VAPOR
LINE
LIQUID LINE
ORIFICE
HOUSING
DISTRIBUTOR
TUBES
LIQUID LINE
MALE EQUALIZER LINE
FITTING (SEE
EQUALIZER LINE
INSTALLATION FOR
FURTHER DETAILS)
SENSING
LINE
EQUALIZER
LINE
CHECK
EXPANSION
VALVE
TEFLON®
RING
(Uncased Coil Shown)
Sensing bulb insulation is required if
mounted external to the coil casing. sensing
bulb installation for bulb positioning.
STUB
END
TEFLON®
RING
LIQUID LINE
ASSEMBLY WITH
BRASS NUT
DISTRIBUTOR
ASSEMBLY
3 -Install one of the provided Teflon®rings around the
stubbed end of the check expansion valve and lightly
lubricate the connector threads and expose surface of
the Teflon®ring with refrigerant oil.
4 -Attach the stubbed end of the check expansion valve to
the liquid line orifice housing. Finger tighten and use an
appropriately sized wrench to turn an additional 1/2 turn
clockwise as illustrated in the figure above, or tighten to
20 ft-lb.
5 -Place the remaining Te flon®washer around the other
end of the check expansion valve. Lightly lubricate
connector threads and expose surface of the Teflon®
ring with refrigerant oil.
6 -Attach the liquid line assembly to the check expansion
valve. Finger tighten and use an appropriately sized
wrench to turn an additional 1/2 turn clockwise as
illustrated in the figure above or tighten to 20 ft-lb.
ON 7/8” AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O'CLOCK
POSITION.
12
ON LINES SMALLER THAN
7/8”, MOUNT SENSING
BULB AT EITHER THE 3 OR
9 O'CLOCK POSITION.
12
BULB
VAPOR LINE
VAPOR LINE
NOTE - NEVER MOUNT THE SENSING BULB ON
BOTTOM OF LINE.
BULB
BULB
BULB
VAPOR LINE
FLARE NUT
COPPER FLARE
SEAL BONNET
MALE BRASS EQUALIZER
LINE FITTING
FLARE SEAL CAP
OR
1
2
3
4
5
6
7
8
9
10
11 12
1/2 Turn
SENSING BULB INSTALLATION
EQUALIZER LINE INSTALLATION
1
2
3
4
5
6
7
8
9
10
11 12
1/8 Turn
1 -Remove and discard either the flare seal cap or flare nut
with copper flare seal bonnet from the equalizer line port
on the vapor line as illustrated in the figure below.
2 -Remove the field-provided
sembly.
INDOOR EXPANSION VALVE INSTALLATION

506860-03 Issue 1946 Page 7 of 27
ATTACH THE MANIFOLD GAUGE SET FOR BRAZING LIQUID AND VAPOR LINE SERVICE VALVES
OUTDOOR
UNIT
LIQUID LINE
VAPOR LINE
LIQUID LINE SERVICE
VALVE
VAPOR LINE
SERVICE
VALVE
ATTACH
GAUGES
INDOOR
UNIT
VAPOR SERVICE PORT MUST BE OPEN
TO ALLOW EXIT POINT FOR NITROGEN
A -Connect gauge set low pressure side to
liquid line service valve (service port).
B -Connect gauge set center port to bottle of
nitrogen with regulator.
C -Remove core from valve in vapor line
service port to allow nitrogen to escape.
NITROGEN
HIGHLOW USE REGULATOR TO FLOW
NITROGEN AT 1 TO 2 PSIG.
B
A
C
WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALV E.
Flow regulated nitrogen (at 1 to 2 psig) through the low-side refrigeration gauge set into the liquid line service port valve, and out of the
vapor line service port valve.
CUT AND DEBUR CAP AND CORE REMOVAL
Cut ends of the refrigerant lines square (free from nicks or dents)
and debur the ends. The pipe must remain round. Do not crimp end
of the line.
Remove service cap and core from
both the vapor and liquid line service
ports.
12
LIQUID LINE SERVICE
VALVE
SERVICE
PORT
CORE
SERVICE PORT
CAP
SERVICE
PORT
CORE
SERVICE
PORT CAP
CUT AND DEBUR
LINE SET SIZE MATCHES
SERVICE VALVE CONNECTION
DO NOT CRIMP SERVICE VALVE
CONNECTOR WHEN PIPE IS
SMALLER THAN CONNECTION
3
VAPOR LINE SERVICE
VALVE
COPPER TUBE
STUB
REFRIGERANT LINE
REDUCER
SERVICE VALV E
CONNECTION
LINE SET SIZE IS SMALLER
THAN CONNECTION
Refrigerant Piping - Brazing Procedures
Before brazing, ensure the system is fully
recovered of all refrigerant. Application of a
brazing torch to a pressurized system may
result in ignition of the refrigerant and oil
mixture. Check the high and low pressures
before applying heat.
WARNING
Brazing alloys and ux contain materials which are
hazardous to your health.
Avoid breathing vapors or fumes from brazing
operations. Perform operations only in well-ventilated
areas.
Wear gloves and protective goggles or face shield to
protect against burns.
Wash hands with soap and water after handling brazing
alloys and ux.
WARNING
Use a manifold gauge set designed for use on R-410A
refrigerant systems.
NOTE

506860-03Issue 1946Page 8 of 27
WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.
LIQUID LINE SERVICE VALVE
LIQUID LINE
BRAZE LINE SET
Wrap both service valves with water-saturated cloths as illustrated here and as mentioned in step 4, before brazing to line set.
Cloths must remain water-saturated throughout the brazing and cool-down process.
WATER-SATURATED
CLOTH
IMPORTANT — Allow braze joint to cool. Apply
additional water-saturated cloths to help cool brazed
joint. Do not remove water-saturated cloths until
piping has cooled. Temperatures above 250ºF will
damage valve seals.
6
VAPOR LINE
WATER-SATURATED
CLOTH
VAPOR LINE
SERVICE VALVE
After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water-saturated cloths to both
services valves to cool piping. Once piping is cool, remove all water-saturated cloths.
WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.
PREPARATION FOR NEXT STEP
7
WRAP SERVICE VALVES
To help protect service valve seals during brazing, wrap water-saturated cloths around service valve bodies and copper tube stubs. Use
additional water-saturated cloths underneath the valve body to protect the base paint.
4
FLOW NITROGEN
Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration gauge set into the valve stem port connection on the liquid service valve and
out of the vapor valve stem port. See steps 3A, 3B and 3C on manifold gauge set connections.
5
WARNING
FIRE, PERSONAL INJURY, OR PROPERTY DAMAGE
may result if you do not wrap a water-saturated cloth around
both liquid and suction line service valve bodies and copper
tube stub while brazing the line set! The braze, when
complete, must be quenched with water to absorb any
residual heat.
Do not open service valves until refrigerant lines and
indoor coil have been leak-tested and evacuated. Refer
to Leak Test and Evacuation section of this manual.
WARNING
While protecting the
service valve seals with
water-saturated cloths,
ensure that water does
NOT enter the system.

506860-03 Issue 1946 Page 9 of 27
TO VAPOR
SERVICE VALVE
HFC-410A
MANIFOLD GAUGE SET
OUTDOOR UNIT
HIGH
LOW
1
2
A
B
NITROGEN
NOTE - Position
canister to deliver
liquid refrigerant.
A -With both manifold valves closed, connect the cylinder of HFC-410A refrigerant to the center port of the
manifold gauge set. Open the valve on the HFC-410A cylinder (vapor only).
B - Open the high pressure side of the manifold to allow HFC-410A into the line set and indoor unit. Weigh in
a trace amount of HFC-410A.[A trace amount is a maximum of two ounces (57 g) refrigerant or three
pounds (31 kPa) pressure.] Close the valve on the HFC-410A cylinder and the valve on the high
pressure side of the manifold gauge set. Disconnect the HFC-410A cylinder.
C - Connect a cylinder of nitrogen with a pressure regulating valve to the center port of the manifold gauge
set.
D - Adjust nitrogen pressure to 150 psig (1034 kPa). Open the valve on the high side of the manifold gauge set
in order to pressurize the line set and the indoor unit.
E - After a few minutes, open one of the service valve ports and verify that the refrigerant added to the
system earlier is measurable with a leak detector.
F -
After the line set has been connected to the indoor and outdoor units, check the line set connections and
indoor unit for leaks. Use the following procedure to test for leaks:
A -Connect the high pressure hose of an HFC-410A manifold gauge set to the vapor valve service port.
NOTE - Normally, the high pressure hose is connected to the liquid line port. However, connecting it
to the vapor port better protects the manifold gauge set from high pressure damage.
B - With both manifold valves closed, connect the cylinder of HFC-410A refrigerant to the center port of
the manifold gauge set.
CONNECT GAUGE SET
TEST FOR LEAKS
NOTE - Later in the procedure, the HFC-410A container will be replaced by the nitrogen container.
After leak testing, disconnect gauges from service ports.
NOTE - Service valve cores remain removed for the following evacuation procedure.
LEAK TEST
Leak Test and Evacuation

506860-03Issue 1946Page 10 of 27
A - Open both manifold valves and start the vacuum pump.
B -
NOTE - During the early stages of evacuation, it is desirable to close the manifold gauge valve at least once. A rapid rise in pressure
indicates a relatively large leak. If this occurs, repeat the leak testing procedure.
NOTE - The term absolute pressure means the total actual pressure above absolute zero within a given volume or system. Absolute
pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.
C - When the absolute pressure reaches 23,000 microns (29.01 inches of
mercury), perform the following:
Close manifold gauge valves.
Close valve on vacuum pump.
Turn off vacuum pump.
Disconnect manifold gauge center port hose from vacuum pump.
Attach manifold center port hose to a nitrogen cylinder with pressure
regulator set to 150 psig (1034 kPa) and purge the hose.
Open manifold gauge valves to break the vacuum in the line set and indoor
unit.
Close manifold gauge valves.
D - 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.
E - Reconnect the manifold gauge to the vacuum pump, turn the pump on, and continue to evacuate the line set and indoor unit until the
absolute pressure does not rise above 500 microns (29.9 inches of mercury) within a 20-minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
F - When the absolute pressure requirement above has been met, disconnect the manifold hose from the vacuum pump and connect it to a
cylinder of HFC-410A positioned to deliver liquid refrigerant. Open the manifold gauge valve 1 to 2 psig in order to release the vacuum in the
line set and indoor unit.
G - Perform the following:
Close manifold gauge valves.
Shut off HFC-410A cylinder.
Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core
tool while maintaining a positive system pressure.
Replace stem caps and finger tighten them, then tighten an additional one-sixth (1/6) of a turn as illustrated.
OUTDOOR
UNIT
TO VAPOR
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
MICRON
GAUGE
VACUUM PUMP
1/4 SAE TEE WITH SWIVEL
COUPLER
500
MANIFOLD
GAUGE SET
HFC-410A
RECOMMEND
MINIMUM 3/8” HOSE
A - Connect low side of manifold gauge set with
1/4 SAE in-line tee to vapor line service valve
B - Connect high side of manifold gauge set to
liquid line service valve
C - Connect available micron gauge connector
on the 1/4 SAE in-line tee.
D - Connect the vacuum pump (with vacuum
gauge) to the center port of the manifold
gauge set. The center port line will be used
later for both the HFC-410A and nitrogen
containers.
HIGH
LOW
1
2
3
4
5
6
7
8
9
10
11 12
1/6 TURN
NITROGEN
3CONNECT GAUGE SET
A
B
C
D
4EVACUATE THE SYSTEM
NOTE - Remove cores from service valves (if not already done).
Possible equipment damage.
Avoid deep vacuum operation. Do not use
compressors to evacuate a system.
Extremely low vacuum can cause internal
arcing and compressor failure. Damage
caused by deep vacuum operation will
void warranty.
WARNING !
EVACUATION
H - Open suction service valve first before liquid valve to release the unit charge into the system. Replace valve
caps and tighten (8 ft. lb.). Caps are the primary seal.
Evacuate the line set and indoor unit until a slight vacuum is indicated on the micron gauge (approximately 23,000 microns or
29.01 inches of mercury).
NOTE - Position
canister to deliver
liquid refrigerant.

506860-03 Issue 1946 Page 11 of 27
Liquid and Suction Line Service Valves
The liquid line and suction line service valves (see Figure
4) and service ports are used for leak testing, evacuation,
charging, and checking charge.
Each valve is equipped with a service port which has a
factory-installed Schrader valve. A service port cap protects
the Schrader valve from contamination and serves as the
primary leak seal.
To Access the Schrader Port:
1. Remove the service port cap with an adjustable
wrench.
2. Connect gauge to the service port.
3. When testing is completed, replace service port cap.
Tighten nger tight, then an additional 1/6 turn.
To Open Liquid or Suction Line Service Valve:
1. Remove stem cap with an adjustable wrench.
2. Use 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.
3. Replace the stem cap. Tighten nger tight, then tighten
an additional 1/6 turn.
To Close Liquid or Suction Line Service Valve:
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
rmly.
3. Replace the stem cap. Tighten nger tight, then tighten
an additional 1/6 turn.
Suction Line (Ball Type) Service Valve
Suction line (ball type) service valves function the same
way as the other valves; the di󰀨erence is in the construction
(see Figure 5).
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.
Figure 4.
Figure 5.

506860-03Issue 1946Page 12 of 27
Electrical Wiring
All eld 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.
Electrical Shock Hazard!
Turn OFF electric power before connecting
unit, performing any maintenance or
removing panels or doors. More than one
disconnect may be required to turn o󰀨 all
power.
FAILURE TO DO SO COULD RESULT IN
BODILY INJURY OR DEATH.
WARNING
Unit must be grounded in accordance with national and
local codes. Failure to ground unit properly can result in
personal injury or death.
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.
WARNING
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.
1. Install line voltage power supply to unit from a properly
sized disconnect switch. Any excess high voltage eld
wiring should be trimmed or secured away from the
low voltage eld wiring.
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 tting. Units are approved for
use only with copper conductors. 24V Class II circuit
connections are made in the low voltage junction box.
A complete unit wiring diagram is located inside the
unit control box cover.
3. Install room thermostat according to thermostat
installation instruction and on an inside wall that is
not subject to drafts, direct sunshine, or other heat
sources.
4. Install low voltage wiring from outdoor to indoor unit
and from thermostat to indoor unit (see Figure 6).
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 eld-installed low and
high voltage circuits.
1Refer to thermostat installation instructions
2If applicable
3Refer to indoor unit installation instructions
4“L” is used for any accessories (e.g. diagnostic /
warning / alarm), used to activate thermostat
warning light
W / W1 / W2 / W3 are auxiliary heat
(supplemental to heat pump).
“E” is emergency heat (disables heat pump).
NOTES:
W3
W2
R
RR
C
CC
W1
W/
W1 W1
Auxiliary Heat
(Heat Pump)
G
GIndoor Blower Only
OO
Heat Pump
Y2 Y2
Thermostat Indoor Unit Outdoor Unit
E
L L
B
Y1 Compressor / 1st Stage Y1
4
1
2
31 2
31 2
1
1
Not Used
L
Auxiliary Heat
(Heat Pump)
Compressor / 2nd Stage
Figure 6. Thermostat Designations -
Non-Communicating

506860-03 Issue 1946 Page 13 of 27
Figure 7.
Indoor Control
Outdoor Unit
Connect single wire
to terminal C
NOTE: On communicating systems, extra wires must terminate on the indoor “C” Comfort SyncTM
terminal strip (RSBus). Use an additional wire to connect all unused wires to “C” terminal on the indoor
control ONLY.
Comfort SyncTM
Thermostat
Connect single wire
to terminal C
All unused wires
All unused wires
Comfort SyncTM Thermostat with
Comfort SyncTM-enabled Furnace / Air Handler and
Non-Communicating Heat Pump
Comfort SyncTM Thermostat with
Comfort SyncTM-enabled Furnace / Air Handler and
Comfort SyncTM-enabled Heat Pump
COMFORT SYNCTM-
ENABLED FURNACE
OR AIR HANDLER
RSBus
RSBus
OPTIONAL
DISCHARGE
AIR SENSOR
COMFORT SYNCTM
THERMOSTAT
COMFORT SYNCTM-
ENABLED HEAT PUMP
RSBus
OPTIONAL
OUTDOOR
AIR SENSOR
OPTIONAL
DISCHARGE
AIR SENSOR
COMFORT SYNCTM-
ENABLED FURNACE
OR AIR HANDLER
COMFORT SYNCTM
THERMOSTAT
NON-COMMUNICATING
HEAT PUMP
1 OR 2 STAGE
NOTES:
Maximum total length of all connections on the RSBus is limited to 1500 ft.
Wire gauge of RSBus wire is 18.
Cut Y1-Y2 on-board link for 2-stage outdoor units
Cut R-O on-board link for outdoor heat pump units
Field Wiring and Routing - Communicating Controls
Maximum length of wiring (18 gauge) for all connections on the RSBus is 1500 feet (457 meters). Wires should be color
coded, with a temperature rating of 95ºF (35ºC) minimum, and solid core (Class II Rated Wiring). All low voltage wiring must
be connected through the low voltage grommet in the control box.

506860-03Issue 1946Page 14 of 27
Start-Up
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.
CAUTION
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and eld-installed wiring for loose
connections.
3. After evacuation is complete, open liquid line and
suction line service valves to release refrigerant
charge (contained in outdoor unit) into system.
4. Replace the stem caps and secure nger tight, then
tighten an additional 1/6 of a turn.
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.
6. Set thermostat for cooling demand, turn on power to
indoor blower, and close the outdoor unit disconnect
switch to start the unit.
7. Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate.
Refrigerant Charging
Excessive amounts of liquid refrigerant entering the
suction line can damage the compressor. When adding
refrigerant, precautions must be taken to control the
ow of liquid into the system. This can be done by using
a liquid vaporizing adapter or manual control using a
sight glass as indicator.
CAUTION
Units are factory charged with the amount of R-410A
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 eld charge.
Table 4. Refrigerant Charge Adjustment
Liquid Line Set Diameter Oz. Per 5 ft. adjust from 15
ft. line set*
3/8 in. 3 oz. per 5 ft.
or 0.6 oz. per 1 ft.
* If line length is greater than 15 ft., add this amount. If line
length is less than 15 ft., remove this amount.
Mineral oils are not compatible with R-410A. If oil must
be added, it must be a polyolester oil.
IMPORTANT
NOTE: Both airow and refrigerant charge must be
monitored for proper system set-up. It may be necessary to
alternately check and adjust the airow and the refrigerant
charge.
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, use the weigh-in method to charge the
unit. Do this after any leaks have been repaired.
1. Recover the refrigerant from the unit.
2. Conduct a leak check, then evacuate as previously
outlined.
3. Weigh in the charge according to the total amount
shown on the unit nameplate.
If weighing facilities are not available or if unit is being
charged during warm weather, use one of the following
procedures.
• For systems using a TXV on the indoor evaporator
and outdoor temperature above 60°F – charge in
cooling mode using the subcooling method and table
provided on the unit access panel.
• For systems below 60°F – charge in heating mode
using the subcooling method and table provided on
the unit access panel. Attach low pressure gauge
hose to auxiliary service port to access suction side in
heating mode.
NOTE: All unit table values are based on 70 to 80°F
indoor return air temperature for cooling mode, and
65°F to 75°F return air temperature for heat mode.

506860-03 Issue 1946 Page 15 of 27
Operation
The outdoor unit and the 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
The unit is equipped with a large capacity bi-ow lter
that keeps the system clean and dry. If replacement is
necessary, replace with one of similar design and capacity.
The replacement lter drier must be suitable for use with
R-410A refrigerant.
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 eld-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 o󰀨 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 su󰀩cient time to prevent compressor
slugging.
Pressure Switch Circuit
The control board includes two pressure switch circuits.
A high pressure switch is connected to the board’s HI-
PS terminals (see Figure 8). The low pressure, or loss-
of-charge pressure, switch is connected to the LO-PS
terminals.
During a single demand cycle, the control board will lock out
the unit after the fth time that the circuit is interrupted by a
pressure switch wired to the control board. In addition, the
diagnostic LEDs will indicate a locked-out pressure switch
after the fth occurrence of an open pressure switch.
The unit will remain locked out until power to the board
is interrupted, then re-established, or until the error is
cleaned.
NOTE: The control board ignores input from the low
pressure switch terminals as follows:
• During the TEST mode
• During the defrost cycle
• During the 90 seconds start-up period
• For the rst 90 seconds each time the reversing valve
switches heat/cool modes
Heat Pump Control-Defrost Operation
The defrost termination pins must be set on the heat pump
control prior to starting the system to ensure proper defrost
operation.
The heat pump control measures di󰀨erential temperatures
to detect when the system is performing poorly because
of frost buildup on the outdoor coil. The heat pump control
self-calibrates when the defrost system starts and after
each system defrost cycle. The heat pump control monitors
ambient temperature, outdoor coil temperature, and total
run time to determine when a defrost cycle is required. The
coil temperature sensor 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.
NOTE: The heat pump control 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 heat pump control initiates
defrost cycles.
Defrost Operating Modes
The heat pump control operational modes are:
• Defrost calibration and operation
• Defrost test
Defrost Termination Temperature (J1)
The heat pump control can be set to terminate the defrost
cycle at 50, 70, 90, or 100°F (10, 21, 32 and 38°C) (see
Figure 8). The termination jumper is factory set at 50°F
(10°C). If the termination jumper is not installed, the default
termination temperature is 90°F (32°C).
NOTE: Colder climates may require a higher defrost
termination temperature setting to maintain a clear coil.
Second Stage Lock-In (J2)
For second-stage heat pumps, if the outdoor ambient
temperature is below the selected compressor lock-in
temperature, the second-stage compressor solenoid will
be energized even without a Y2 thermostat input. If the
jumper is not connected to one of the temperature selection
pins (40, 45, 50, 55°F) (see Figure 8), the second-stage
lock-in feature will not be activated. Factory default is 40ºF.

506860-03Issue 1946Page 16 of 27
Fan Cycling (J3)
When the jumper is “ON,” the fan will cycle (see Figure
8) for ve minutes if the outdoor ambient air temperature
is between 15ºF and 35ºF and the compressor has been
OFF for 25 to 30 minutes. This option helps reduce the
potential for ice build-up on the orice ring during OFF
cycles greater than 25 to 30 minutes.
Shift Delay (J4)
During the defrost cycle, if the jumper is in the “ON” position,
there will be a compressor start delay of 30 seconds to
reduce the shifting noise of the reversing valve.
Time Delay
The timed-o󰀨 delay is 5 minutes long. The delay helps
to protect the compressor from short cycling in case the
power to the unit is interrupted or a pressure switch opens.
Figure 8. Control Board
Communicating System
For a communicating system, the Comfort Sync thermostat must be
used. The complete configuration of the outdoor unit is performed
using the Comfort Sync thermostat. For complete details on how to
integrate this unit into a Comfort Sync-enabled system, please refer
to the Comfort Sync Wi-Fi installer’s system setup guide.
Non-Communicating System
For systems with a non-communicating thermostat, the system will
operate based on the settings of the jumpers located on the control
board. All system settings must be done at the control board.
(HP Only)
Compressor
Shift Delay
30
30 second
Delay
(Default)
No Delay
(Two-Stage Heat
Pump Only)
Second Stage
Lock-In Temperature
55
50
45
40
55
50
45
40
55
50
45
40
55
50
45
40
50 Degree
Target
55 Degree
Target
45 Degree
Target
40Degree
Target
(Default)
Defrost Termination
Temperature
(HP Only)
100
90
70
50
100
90
70
50
100
90
70
50
100
90
70
50
100
90
70
50
50 Degree
Target
70 Degree
Target
90 Degree
Target
100 Degree
Target
90
Default when
jumper is
removed or
missing
7-Segment
Display

506860-03 Issue 1946 Page 17 of 27
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E105 Device communication problem - No other devices on RS
BUS (Communication system).
Equipment is unable to communicate. Indicates numerous
message errors. In most cases, errors are related to electrical
noise. Make sure high voltage power is separated from
RSBus. Check for mis-wired and/or loose connections
between the stat, indoor unit, and outdoor unit. Check for a
high voltage source of noise close to the system. Fault clears
after communication is restored.
E120 Unresponsive device (Communicating systems only). Usually caused by delay in outdoor unit responding to indoor
unit poling. Recycle power. Check all wiring connections.
Cleared after unresponsive device responds to any inquiry.
E124 Active communicating thermostat signal missing for more
than 3 minutes (Communicating systems only).
Equipment lost communication with the thermostat. Check
four wiring connections, ohm wires, and cycle power at the
thermostat. Alert stops all services and waits for heartbeat
message from thermostat (subnet controller). Cleared after
valid thermostat (subnet) message is received.
E125 Control failed self-check, internal error, failed hardware.
Will restart if error recovers, Integrated control not
communicating Covers hardware errors (ame sense
circuit faults, pin shorts, etc).
Hardware problem on the control. Cycle power on control.
Replace if problem prevents service and is persistent. Cleared
300 seconds after fault recovered.
E126 Control internal communication problem. Hardware problem on the control. Cycle power on control.
Replace if problem prevents service and is persistent. Cleared
300 seconds after fault recovered.
E131 Corrupted control parameters (Verify conguration of
system) (Communicating systems only).
Recongure the system. Replace control if heating or cooling
is not available. Only applicable in the communicating mode
not in startup. Exit from Commissioning and Execute Se+
factory Default mode. Control will still operate on default
parameter settings.
NOTE: Additional codes may be found in the Comfort Sync room thermostat manual.
Table 5. 7-Segment Alert and System Status Codes
7-Segment Alert and System Status Codes
Alert codes are displayed using the 7-segment display
located on the outdoor control.
NOTE: System fault and lockout 7-segment display
alarm codes take precedence over system status codes
(cooling, heating stages or defrost/dehumidication). Only
the latest active fault or lockout alarm code, if present, will
be displayed. If no fault or lockout codes are active, then
system status codes are routinely displayed.
The 7-segment will display an abnormal condition (error
code) when detected in the system. A list of the codes are
shown in Table 5.
Resetting Alert Codes
Alert codes can be reset manually or automatically:
Manual Reset
Manual reset can be achieved by one of the following
methods:
• Disconnecting R wire from the main control’s R
terminal.
• Turning the indoor unit o󰀨 and back ON again. After
power up, all existing codes will display for 60 seconds
and then clear.
Automatic Reset
After an alert is detected, the main control continues to
monitor the unit’s system and compressor operations.
When/if conditions return to normal, the alert code is turned
o󰀨 automatically.

506860-03Issue 1946Page 18 of 27
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E180 Outdoor air temperature sensor failure. Only shown if
shorted or out of range (Communicating systems only)
Compare outdoor sensor resistance to temperature
resistance charts in unit installation instructions. Replace
sensor pack if necessary. At beginning of (any) conguration,
furnace or air handler control will sense outdoor air and
discharge air temperature sensor(s) If detected (reading
in range), appropriate feature will be set as installed and
that could be seen in 'About ' screen. In normal operation
after control recognizes sensors, alarm will be sent if valid
temperature reading is lost. To get rid of setting and alarm,
redo conguration and make sure that temperature sensor is
marked as not installed in indoor Unit ‘About’ screen. When
indoor unit control is replaced thermostat will ‘tell’ new control
if temperature sensor is in system or not. Clears 30 seconds
after fault recovered.
E409 LSOM - Compressor low voltage. Secondary voltages below 18VAC. After 10 minutes, operation
is discontinued. Clears the code after voltage is higher than
20VAC for 2 seconds or after power reset.
E410 The outdoor unit pressure is below the required limit. Unit pressure is below the lower limit. The system is shut
down. The low pressure switch for R-410A will open at 40
PSIG and close at 90 PSIG. Conrm that the system is
properly charged with refrigerant. Check TXV, indoor unit
blower motor, dirty lters or clogged refrigerant lter. Conrm
that the evaporator coil is clean. The alarm clears after the
pressure switch closes or after a power rest.
E411 The low pressure switch has opened 5 times during one
cooling cycle. As a result, the system will shut down.
Open low pressure switch error count reached 5 strikes. The
low pressure switch for R-410A will open at 40 PSIG and
close at 90 PSIG. Conrm that the system is properly charged
with refrigerant. Check TXV, indoor unit blower motor, dirty
lters or clogged refrigerant lter. Conrm that the evaporator
coil is clean. The alarm clears after a power rest.
E412 The outdoor unit pressure is above the required limit. The
system will shut down.
Unit pressure is above the upper limit. System is shut down.
The high pressure switch for R-410A will open at 590 PSIG
and close at 418 PSIG. Conrm that the system is properly
charged with refrigerant. Check condenser fan motor, TXV,
indoor unit blower motor, stuck reversing valve or clogged
refrigerant lter. Conrm that the outdoor unit is clean. The
alarm clears after 4 consecutive normal compressor run
cycles, the pressure switch closes or a power reset.
E413 The high pressure switch has opened 5 times during one
cooling cycle. As a result, the Comfort Sync thermostat
will shut down.
Open high pressure switch error count reached 5 strikes.
System is shut down. The high pressure switch for R-410A will
open at 590 PSIG and close at 418 PSIG. Conrm that the
system is properly charged with refrigerant. Check condenser
fan motor, TXV, indoor unit blower motor, stuck reversing
valve or clogged refrigerant lter. Conrm that the outdoor unit
is clean. The alarm clears after a power reset.
E414 The discharge line temperature is higher than the
recommended upper limit of 279°F.
Discharge line temperature is > 279°F. Conrm that the
system is properly charged with refrigerant. Check system
operating pressures and compare to unit charging charts in
installation manual. Conrm that the outdoor unit is clean. The
alarm clears after the discharge temperature is < 225°F.
E415 The discharge line temperature has been consistently
higher than the recommended upper limit of 279°F.
Discharge line high temperature error count reached 5
strikes. Conrm that the system is properly charged with
refrigerant. Check system operating pressures and compare
to unit charging charts in installation manual. Conrm that the
outdoor unit is clean. The alarm clears after the discharge
temperature is < 225°F. The alarm clears after a power reset.
NOTE: Additional codes may be found in the Comfort Sync room thermostat manual.
Table 5. 7-Segment Alert and System Status Codes

506860-03 Issue 1946 Page 19 of 27
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E416 The outdoor coil sensor is either open, short-circuited
or the temperature is out of sensor range. As a result,
the outdoor unit control will not perform any defrost
tempering.
Coil sensor being detected open or shorted, or temperature is
out of coil sensor range. Outdoor unit control will not perform
demand or time/temperature defrost operation. System will
still heat or cool. Check the resistance of the coil sensor and
compare to temperature resistance chart. Replace coil sensor
if needed. The alarm clears when outdoor unit control detects
proper coil sensor readings or after a power reset.
E417 The outdoor unit discharge sensor is either open, short-
circuited or the temperature is out of sensor range. As a
result, the outdoor unit control will not perform any defrost
tempering.
Outdoor unit control detects open or shorted discharge
sensor, or temperature that is out of discharge sensor range.
Check the resistance of the discharge sensor and compare
to temperature resistance chart; replace if needed. Reset
by replacing the discharge sensor. This fault is detected
by allowing the unit to run for 90 seconds before checking
discharge sensor resistance. If the discharge sensor
resistance is not within range after 90 seconds, the board will
count one fault. After 5 faults, the board will lock out. Check
for proper sensor reading and attachment to line. The alarm
clears after a power reset.
E418 There is a faulty W output circuit. Faulty W output circuit. Conrm that the unit is not running.
Check for mis-wiring. Disconnect thermostat lines from W
and verify 24VAC on the W. If 24VAC is present, replace the
board.
E419 The W output on the outdoor unit has reported more
than 5 errors. As a result, the system has shut down the
outdoor unit.
W output hardware fault count reached 5 strikes.
E420 The heat pump defrost cycle has taken more than 20
minutes to complete.
Defrost cycle lasts longer than 20 minutes. This alarm is
applicable with non-communicating heat pump system only.
Check heat pump defrost operation. The alarm is cleared after
the “W1” signal is removed.
E421 The W output terminal on the outdoor unit is not wired
correctly.
Voltage sensed on W and O when Y1 thermostat input is
deactivated. Another device or wiring fault is energizing W
check wiring. The alarm clears when wiring is corrected or
after a power reset.
NOTE: Additional codes may be found in the Comfort Sync room thermostat manual.
Table 5. 7-Segment Alert and System Status Codes

506860-03Issue 1946Page 20 of 27
Mode Description Example of Display
Power Up / Reset
Unit type and number of stages is
displayed. Verify conguration with
information published on the unit
nameplate. If the information is
incorrect, refer to ow chart “Manual
Conguration of Unit Type” to
recongure control.
1 Stage AC: 1AC
2 Stage AC: 2AC
1 Stage AC: 1HP
1 Stage AC: 2HP
Power-Up 7-Segment Display String
2 H P ___
___
___
___
___
___
Unit Type / Stages No Capacity No Fan Prole
Power Up / Reset
following display
of self-discovered
conguration
Unit nominal capacity is displayed. If
not programmed, then three horizontal
lines and the decimal point are
displayed for 2 seconds.
Power up nominal capacity display of an 4SHP - LS136
Power-Up 7-Segment Display String
2 H P 3 6 ___
___
___
Unit Type / Stages Capacity No Fan Prole
Power Up / Reset
following display
of nominal
capacity
Fan Prole code (a single- or two-digit
number).
Displays the number of the selected fan prole.
Power-Up 7-Segment Display String
2 H P 3 6 3
Unit Type / Stages Capacity Fan Prole
Idle Mode Decimal point blinks at 1 Hz Idle Mode: Decimal point blinks at 1 Hz (0.5 second on, 0.5 second
o󰀨). Display OFF.
Soft Disabled Top and bottom horizontal line and
decimal point blink at 1 Hz.
Soft Disabled: Top and bottom horizontal line and decimal point blink
at 1 Hz (0.5 second on, 0.5 second o󰀨). NOTE: Control should be
replaced.
O.E.M. Test Mode All segments ashing at 2 Hz (unless error is detected). NOTE: Control
should be replaced.
Anti-Short Cycle
Delay
Middle line shall blink at 1 Hz for 2 seconds, followed by a two-second
display of the rounded up number of minutes left in the timer (two
minutes, one second shall be displayed as “3”). The Anti-Short Cycle
Delay time remaining is displayed when the delay is active.
Cooling Stage Shows what stage of heat pump is
currently operating.
Following string is repeated if two-stage cooling is active with outdoor
fan speed set at 700 RPM. NOTE: A - If available, displays outdoor
ambient temperature.
C2 pause F700 pause
Heat Pump Stage Shows what stage of heat pump is
currently operating.
Following string is repeated if rst-stage cooling is active with outdoor
fan speed set at 600 RPM. NOTE: A - If available, displays outdoor
ambient temperature.
H1 pause F600 pause
*Information will be displayed, but does not apply to this unit.
Table 6. Outdoor Control 7-Segment Unit Status Displays