Lennox MPA009S4S Service Manual page 139

Error Code:
F3
Description: Compressor discharge temperature sensor error
General Note: When the compressor discharge temperature(T5) is more than 115°C for 10 seconds, the compressor will stop and restart
till T5 is less than 90°C.
Temperature protection of compressor.
Check whether the compressor discharge temp. is
more than 115°C ?
Check whether the connection is right between com-
pressor discharge temp. sensor and PCB according to
wiring diagrams?
Measure the resistance value of compressor dis-
charge temp. sensor. If the value is not normal is
normal refer to the Appendix 2?
Replace outdoor main PCB.
Replace high pressure valve assy.
No
Yes
Yes
No
Yes
Check whether the
refrigerant is leak.
No
No
Correct the wiring con-
nection.
No
Replace the compressor
discharge temp. sensor.
139
Yes
Stop leaking and add
refrigerant.