LG Therma V fault 03

What it means

Error (serious fail - system cannot be used before repair). Communication between wired remote controller and indoor unit is not possible.

Likely causes

1. Communication between wired remote controller and indoor unit is not possible
2. Abnormal refrigerant pressure
3. Compressor wiring reverse phase loss
4. Inverter PCB assembly or connector connection fault
5. Communication line shorted or disconnected
6. Main PCB(Indoor) CN-REMO voltage not present (fault on Main PCB)
7. Noise near wired remote control or communication line

Where to start

1. Check if the product installation is in good condition: check if the fan is locked, check the shield around the heat exchanger, check the distance between the product and the wall, check the condition of piping such as bending of the pipe, check EEV operation status and connection status, check refrigerant pressure. If No: remove the cause of the abnormality.
2. If installation OK, check if the compressor is normal: check compressor restraint, check compressor wiring (reverse phase loss), check short circuit/opening of internal connection line, check resistance between each terminal of compressor (0.529 ~ 0.631 Ω ± 7%), check insulation resistance between compressor terminal and pipe (50 MΩ). If No: compressor wiring check / compressor replacement.
3. If compressor OK, check if the inverter PCB assembly and connector connections are in good condition. If No: inverter reassembly, connector reconnection, replace connector when defective.