GSZH5 Service Manual
91
SERVICING
WARNING
• If the compressor starts and continues to run, the
cause for failure is somewhere else in the system.
• If the compressor fails to start - replace.
COPELAND COMPRESSOR
03 A L
YEAR
MONTH
SERIAL
NUMBER
PLANT
Verify the proper rotation of Copeland scroll compressors
as follows:
normal and does not harm the compressor.
1. Install gauges and verify that the suction pressure
drops while the discharge pressure increases.
2. Listen for normal compressor sound levels. Reverse
rotation results in elevated or unusual sound levels.
3. Reverse rotation will result in substantially reduced
amp draw from tabulated values.
To correct improper rotation, switch any two power supply
leads at the outdoor unit contactor.
The 3-phase scroll compressors are direction of rotation
sensitive. They will rotate in either direction depending on
the phasing of the power. There is no negative impact on
durability caused by operating 3-phase compressors in
reversed rotation. The compressor’s internal protector will
trip, de-energizing the compressor. Continued operation
of 3-phase scroll compressors with the rotation reversed
will contribute to compressor failure. All 3-phase scroll
compressors should be checked for correct phase rotation.
The crankcase heater must be energized a minimum of
four (4) hours before the condensing unit is operated.
Crankcase heaters are used to prevent migration or
accumulation of refrigerant in the compressor crankcase
pumping on start up.
A crankcase heater will not prevent compressor damage
due to a oodback or over charge condition.
WARNING
1. Disconnect the heater lead in wires.
2. Using an ohmmeter, check heater continuity - should
test continuous. If not, replace.
ohms. The resistance will become greater as the
temperature of the compressor shell increases.
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
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.
Troubleshooting the Reversing Valve for Electrical
Failure
1. Place unit into the cooling mode. Test for 24 volts at the
solenoid. If there is no voltage present at coil, check
the control voltage.
2. If voltage is present, loosen the nut on the top of the
coil. Remove the coil, there should be slight resistance.
3. If the slight resistance is felt, remove the coil. As you
remove the coil listen carefully, an audible click should
be detected. The clicking is due to the movement of the
pilot valve plunger. The absence of a clicking sound
indicates the plunger is stuck.
Troubleshooting Mechanical Failures on a Reversing
Valve by Pressure
1. Troubleshooting the reversing valve can be done by
pressure and touch.
2. Raise the head pressure. In the cooling mode block
the fan exhaust. Once head pressure has been raised,
cycle between cooling and heating and see if the piston
can be freed.