Midea MCH2U-18PHH2 Service Manual page 86

8.4.2.11 P4 (Temperature protection of compressor discharge) diagnosis and solution.
Error Code
Malfunction conditions
Potential causes
Trouble shooting:
P4
When the compressor discharge temperature(T5) is more
than 115℃ for 10 seconds, the compressor will stop
restart till T5 is less than 90℃.
● Refrigerant leakage
● Wiring mistake
● Faulty discharge temperature sensor
● Faulty outdoor PCB
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