15
MODEL
5
8
10
15
20
GPHM52441
X
X
X
GPHM53041
X
X
X
X
GPHM53641
X
X
X
X
GPHM54241
X
X
X
X
GPHM54841
X
X
X
X
X
ELECTRIC HEAT kW
Electric Heat kW
Figure 14
MAINTENANCE
WARNING
HIGH VOLTAGE
Disconnect all power before servicing or
installing this unit. Multiple power sources
may be present. Failure to do so may cause
property damage, personal injury or death.
The Self Contained Package Air Conditioner and Heat
Pump should operate for many years without excessive
service calls if the unit is installed properly. However it
is recommended that the homeowner inspect the unit
before a seasonal start up. The coils should be free of
debris so adequate air flow is achieved. The return and
supply registers should be free of any obstructions. The
filters should be cleaned or replaced. These few steps
will help to keep the product up time to a maximum. The
Troubleshooting Chart (see Appendix) should help in
identifying problems if the unit does not operate properly.
SERVICE
THE FOLLOWING INFORMATION IS FOR USE BY
QUALIFIED SERVICE AGENCY ONLY: OTHERS
SHOULD NOT ATTEMPT TO SERVICE THIS
EQUIPMENT.
Common Causes of Unsatisfactory Operation of
Heat Pump on the Heating Cycle
Inadequate Air Volume Through Indoor Coil
When a heat pump is in the heating cycle, the indoor coil
is functioning as a condenser. The return air filter must
always be clean, and sufficient air volume must pass
through the indoor coil to prevent excessive discharge
pressure, and high pressure cut out.
Outside Air into Return Duct
Do not introduce cold outside air into the return duct of a
heat pump installation. Do not allow air entering the indoor
coil to drop below 65°F. Air below this temperature will
cause low discharge pressure, thus low suction pressure,
and excessive defrost cycling resulting in low heating
output. It may also cause false defrosting.
Undercharge
An undercharged heat pump on the heating cycle will
cause low discharge pressure resulting in low suction
pressure and frost accumulation on the outdoor coil.
Poor “Terminating” Sensor contact
The unit’s defrost terminating sensor must make good
thermal contact with the outdoor coil tubing. Poor contact
may not terminate the unit’s defrost cycle quickly enough
to prevent the unit from cutting out on high discharge
pressure.
Malfunctioning Reversing Valve - This may be due
to:
1. Solenoid not energized -
In order to determine if the
solenoid is energized, touch the nut that holds the
solenoid cover in place with a screwdriver. If the nut
magnetically holds the screwdriver, the solenoid is
energized and the unit is in the cooling cycle.
2. No voltage at unit’s solenoid
- Check unit voltage. If
no voltage, check wiring circuit.
3. Valve will not shift:
a. Undercharged
- Check for leaks;
b. Valve Body Damaged
- Replace valve;
c. Unit Properly Charged
- If it is on the heating
cycle, raise the discharge pressure by restricting
air flow through the indoor coil. If the valve
does not shift, tap it lightly on both ends with a
screwdriver handle. DO NOT TAP THE VALVE
BODY. If the unit is on the cooling cycle, raise the
discharge pressure by restricting air flow through
the outdoor coil. If the valve does not shift after
the above attempts, cut the unit off and wait until
the discharge and suction pressure equalize, and
repeat above steps. If the valve does not shift,
replace it.
REVERSING VALVE TROUBLESHOOTING
Checking Reversing Valve and Solenoid
Reversing valve used in heat pumps could potentially leak
internally. Discharge gases can leak into the suction inside
the valve. Compound gages will give the same symptoms
as bad compressor valves or broken scroll flanks. The
temperature between true suction and the suction line after
the valve should not be greater than 4 degrees. Note: The
center tube is always the suction line and should be cold.
