Midea M2OC-18HFN1-M Service Manual page 84

9.4.2.12 P4(Temperature protection of compressor discharge) error diagnosis and solution.
Error Code
Malfunction decision
conditions
Supposed causes
Trouble shooting:
Temperature protection of
compressor discharge
Check whether the
compressor discharge temp.
is more than 115° C ?
No
Check whether the wiring
connection is right between
compressor discharge temp.
sensor and PCB according
to wiring diagrams?
Yes
Judge: The
discharge temp.
sensor is broken
Method: Check whether the
resistance of compressor
discharge temp. sensor is
right refer to the Appendix 2
Yes
Replace outdoor main board
P4
When the compressor discharge temperature(Tp) is more
than 115℃ for 10 seconds, the compressor will stop
restart till Tp is less than 90℃.
● Refrigerant leakage
● Wiring mistake
● The discharge temperature sensor faulty
● Outdoor PCB faulty
Check whether the
Yes
refrigerant is leak
No Correct the wiring connection
No Replace the compressor discharge temp. sensor
Yes Stop leaking and add refrigerant
Trouble is solved
and