13
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 airflow 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 airflow 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.
WARNING
HIGH
VOLTAGE
!
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR INSTALLING
THIS UNIT.
M
ULTIPLE POWER SOURCES MAY BE PRESENT. FAILU
TO DO SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY O
DEATH.
RE
R
