Mitsubishi Electric PLA Series Service Manual page 24

Abnormal point and detection method
Check code
Abnormal refrigerant circuit
During Cooling, Dry, or Auto Cooling
operation, the following conditions are
regarded as failures when detected for 1
second.
a) The compressor continues to run for 30
PL or more seconds.
b) The liquid pipe temperature or the
condense/evaporator temperature is
75°C or more.
These detected errors will not be
cancelled until the power source is
reset.
OCH529A
Cause
1 Abnormal operation of 4-way
valve
2 Disconnection of or leakage in
refrigerant pipes
3 Air into refrigerant piping
4 Abnormal operation (no rotation)
of indoor fan
· Defective fan motor.
· Defective indoor control board.
5 Defective refrigerant circuit
(clogging)
24
Countermeasure
1 When this error occurs, be sure to replace
the 4-way valve.
2 Check refrigerant pipes for disconnection or
leakage.
3 After the recovery of refrigerant, vacuum dry
the whole refrigerant circuit.
4 Refer to "9-6-2. DC Fan motor (Fan motor/
Indoor controller board)".
5 Check refrigerant circuit for operation.
Purge air in refrigerant circuit to avoid
entry of moisture or air into refrigerant
circuit which could cause abnormal high
pressure, or replace refrigerant.