GPH16H Installation Instructions

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

ISCONNECT

ALL

POWER BEFORE SERVICING OR INSTALLING

THIS UNIT.

ULTIPLE POWER SOURCES MAY BE PRESENT. FAILU

TO DO SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY O

DEATH.