Service Manual

8.4.2.12 P4 (Temperature protection of compressor discharge) error diagnosis and solution.
Error Code
P4
Malfunction decision
conditions
When the compressor discharge temperature(T5) is more
than 239ºF (115ºC) for 10 seconds, the compressor will
stop andrestart till T5 is less than 194ºF (90ºC).
Supposed causes
● Refrigerant leakage
● Wiring mistake
● The discharge temperature sensor faulty
● Outdoor PCB faulty
Trouble shooting:
Temperature protection of
compressor discharge
Temperature protection of
compressor discharge
Check whether the
connection is right between
compressor discharge temp.
sensor and PCB according
to wiring diagrams?
Check whether the
connection is right between
compressor discharge temp.
sensor and PCB according
to wiring diagrams?
Measure the resistance value
of compressor discharge
temp. sensor. If the value is
not normal is normal refer to
the Appendix 2?
Measure the resistance value
of compressor discharge
temp. sensor. If the value is
not normal is normal refer to
the Appendix 2?
No
Yes
Yes
No
Correct the wiring connection
Correct the wiring connection
Stop leaking and add refrigerant
Stop leaking and add refrigerant
Replace the compressor discharge temp. sensor
Replace the compressor discharge temp. sensorNo
Yes
Replace high pressure valve assy
Replace high pressure valve assy
Yes
No
Replace outdoor main PCB
Replace outdoor main PCB
No
Check whether the
refrigerant is leak
Check whether the
refrigerant is leak
Check whether the
compresor discharge temp. is
more than 239ºF (115ºC)?