SYSTEM OPERATION
22
EXPANSION VALVE/CHECK VALVE ASSEMBLY
IN COOLING OPERATION
EXPANSION VALVE/CHECK VALVE ASSEMBLY
IN HEATING OPERATION
Most expansion valves used in current Goodman/Amana
®
Brand Heat Pump products
use an internally checked expansion valve.
This type of expansion valve does not require an external check valve as shown above.
However, the principle of operation is the same.
With a heat pump the reversing valve can leak. Discharge
gases can leak into the suction inside the valve. Compound
gages will give the same symptoms as bad compressor
valves. The temperature between true suction and the
suction line after the valve should not be greater than 4
degrees.
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.
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.
1. When operating properly the valve contains refrigerant
gases at certain temperatures.
2. The discharge line should be the same temperature
after the valves discharge line.
3. The true suction should be the same as the suction line
after the valve. If there is a 4-degree dierence, the
valve is leaking.
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