Midea M-Thermal Arctic HT R290 Mono fault EA

What it means

Protects the compressor when discharge temperature (Tp) is below suction temperature (Th) for more than 12 minutes after compressor operates. Also triggered by running time ≥12 mins with Tp<-20°C or Tp<Th lasting 30s.

Likely causes

1. Discharge temperature abnormally low relative to suction temperature Expansion valve stuck open, refrigerant overcharge, compressor valve leakage, low load condition
2. Loose, misconnected, broken or moisturized sensor connection
3. Sensor short-circuit (resistance < 0.5 kΩ)
4. Sensor failure (resistance > 380 kΩ)
5. Resistance inconsistent with resistance characteristics table
6. Sensor probe dislodged from installation position
7. Main Control PCB failure
8. Discharge temperature below suction temperature for extended period
9. Low refrigerant charge or flow issue causing insufficient discharge superheat
10. Tp<-20°C condition or Tp<Th lasting 30s during compressor run
11. Flow switch leak due to faulty sealing ring
12. Pump idling due to insufficient water/air in circuit
13. Feedback signal cable CN17 not connected properly
14. Water temperature sensor resistance does not match expected characteristics table value
15. Unit capacity not matched to the system (oversized or undersized)
16. Heat exchanger coil in DHW tank too small (insufficient heat exchange area)
17. Insufficient water volume in system / high water side resistance due to lack of buffer tank
18. Water pump leak due to faulty sealing ring
19. Flow switch FS plug (CN8) is not connected properly
20. The water flow in the pipe is not consistent with arrow on the flow switch
21. Water flow switch mechanically damaged (rake does not trigger contact closure)
22. Abnormal state detected requiring compressor protection
23. Set temperature reached (normal stop)
24. Abnormal system state detected

Where to start

1. Monitor discharge temperature (Tp) and suction temperature (Th) during compressor operation
2. Track compressor running time against 12 minute threshold for EA logic
3. Monitor discharge and suction temperatures, check expansion valve operation, verify system load Monitor discharge and suction temperature differential for duration exceeding 5 minutes Monitor discharge temperature versus suction temperature for duration exceeding 5 minutes Monitor discharge temperature versus suction temperature for duration exceeding 5 minutes Monitor discharge and suction temperatures, check expansion valve operation, verify system load