Carrier 38MGRQ36D 3 Series - Temperature Protection of Compressor Discharge Error (P4)

60 Specifications subject to change without notice. 38MGR-04SM
DIAGNOSIS AND SOLUTION (CONT)
Temperature protection of compressor discharge error (P4)
Troubleshooting
ERROR CODE P4
MALFUNCTION DECISION
CONDITIONS
When the compressor discharge temperature (T5) is more than 239
° F for ten seconds, the compressor
stops and restarts when T5 is less than 194
° F.
SUPPOSED CAUSES
• Refrigerant leakage
• Wiring mistake
• The discharge temperature sensor faulty
• Outdoor PCB faulty
No
Yes
Yes
No
No
Yes Yes
No
No
Ch k h h h
g
Temperature Protection of
the Compressor Discharge
Check if the compressor
discharge temp. is higher
than 239°F (115°C).
Check if the refrigerant
is leaking.
Stop the leak and add refrigerant.
Check if the connection is right
between the compressor
discharge temperature sensor
and the PCB based on the
wiring diagrams.
Correct the wiring connection.
Measure the compressor discharge
temperature sensor resistance value.
If the value is not normal, refer to
Appendix 2.
Replace the compressor discharge temp. sensor.
Replace the outdoor main PCB.
Replace the high pressure
valve assembly.