Unique CU Series, Service Manual And Spare Parts List

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9.3 Poor Heating Troubleshooting.
Symptom Probable Cause Corrective Action
1 Refrigerant flow
failure 1. Refrigerant gas
shortage.
2.
Excessive overcharging
of refrigerant.
3.
Gas leakage.
4.
Clogging of strainer or
capillary tube.
5.
4-Way valve is
defective.
6.
Solenoid 4-Way valve is
defective.
7.
Compressor is defective.
8.
Service valves are not
fully open.
1. Charge refrigerant gas.
2.
Recharge gas.
3.
Repair leakage.
4.
Replace strainer.
5.
Replace 4-Way valve.
6.
Replace solenoid.
7.
Replace compressor.
8.
Open the valves full.
2
Air circulation
failure.
Air filter is clogged. Clean air filter.
3 Installation failure. 1. Location of the indoor or
the outdoor units is not
according to the
instructions.
2. Refrigerant tubes between
the units are not installed
according to the
instructions.
1. Relocate units.
2. Relocate or replace tubes.
4 Defrost failure. T2-T2 Thermistor is defective. Replace T2-T2 Thermistor.