Midea R32 M thermal Arctic Mono fault L4

What it means

MCE error detected by refrigerant system main PCB. Displayed as P6/H4 on user interface.

Likely causes

1. Compressor is over-current
2. Inverter PCB has malfunctioned
3. Inverter module damaged
4. DC bus low voltage protection
5. DC bus high voltage protection
6. Software over current protection
7. Inverter PCB failure (if appears immediately on power-on)
8. Compressor over-current (if appears during running at speed over 60rps)
9. Inverter PCB failure (if compressor current is normal during running condition)
10. Inverter module has overheated
11. Inverter module is over-current (compressor failure)
12. Inverter module failed
13. Motor control error
14. Discharge temperature exceeding 105°C indicating high compressor load or high ambient/system conditions
15. Compressor current exceeding Currentmax threshold

Where to start

1. Restart unit
2. Use clip-on ammeter to measure compressor current
3. Check: Is the inverter module damaged? Measure the resistance between each of U, V and W and each of P and N on the inverter module.