Midea M2OC-18HFN1-M Service Manual page 78

9.4.2.9 P1(High pressure protection) error diagnosis and solution. (Only for M4OC-36HRFN1-M)
Error Code
Malfunction decision
conditions
Supposed causes
Trouble shooting:
P1
If the sampling voltage is not 5V, the LED will display the
failure.
● Wiring mistake
● Over load protector faulty
● System block
● Outdoor PCB faulty
High pressure protection
Judge 1: Whether the wiring
between the high pressure
switch and main control No
board is connected well or
correctly
Yes
Judge 2: Whether
the high pressure
protector is broken
Method: Short connect the high
pressure protector socket,
check whether the system can Yes
run normally or test the
resistance.
No
Check whether
the refrigerant
system is ok
Judge 3: Check whether the
outdoor ambient
Yes
temperature is higher than
43℃
No
Judge 4: Check whether the
outdoor unit is bad Yes
ventilation
No
Judge 5: Check whether the
Yes
heat exchanger is dirty
Judge 6: Check whether the
Yes
refrigerant pipe is blocked
Replace outdoor main board
Connect it well
Replace high pressure protector
Stop the unit
Make the outdoor unit ventilate well
Clean the heat exchanger
Let the refrigerant out, then use the
high pressure nitrogen or refrigerant to
blow pipe, vacuumize and charge the
refrigerant again