Midea R32 M thermal Arctic Mono fault L1

What it means

DC bus low voltage protection detected by refrigerant system main PCB. Displayed as P6/H4 on user interface.

Likely causes

1. Power supply is abnormal
2. P N +15V wire not connected properly
3. Voltage between N and +15 is abnormal
4. DC voltage between P and N is abnormal
5. Power supply or bridge rectifier failure
6. Relay on outdoor unit main PCB is open (if occurring after compressor running over 20rps)
7. Inverter module failure
8. DC bus voltage below minimum threshold
9. DC bus low voltage protection
10. P N +15V wire on refrigerant system main PCB not connected properly
11. Abnormal DC voltage between terminal P and N (power supply or three phase bridge rectifier fault)
12. Main PCB failure
13. Inverter module damaged
14. Power supply issue

Where to start

1. Check power supply voltage
2. Check P N +15V wire connections
3. Measure voltage between N and +15