LG Therma V fault CH27

What it means

Transfer of signals with detection of the flow of over-current in PSC (Power Switching Circuit) / PFC (Power Factor Correction).

Likely causes

1. Reactor PCB incorrect wiring
2. PCB Internal Components (PFC Module) Burnout
3. Power cable or communication cable not completely connected (test operation fails to start)
4. Incorrect pipe length or amount of refrigerant
5. Abnormal refrigerant pressure
6. Compressor wiring reverse phase loss
7. Inverter PCB assembly or connector connection fault
8. Communication line shorted or disconnected
9. Main PCB(Indoor) CN-REMO voltage not present (fault on Main PCB)
10. Noise near wired remote control or communication line

Where to start

1. If circuit breaker capacity is proper, check if Reactor PCB connection is normal. If not normal, check Reactor PCB assembly normality and replace Reactor PCB assembly if abnormality found.
2. If Reactor PCB connection is normal, check if Outdoor PCB PSC/PFC Module is normal. If not normal, check Inverter PCB assembly PFC part and replace PCB assembly if abnormality found.
3. Operate the unit in heating mode and check whether Test operation starts; if No, check whether the power cable and communication cable are completely connected.