Lennox MPB036S4M

123
Error Code: P4
Description: Hightemperaturesensedatcompressordischargeline.
General Note: Whenthecompressordischargetemperature(T5)ismorethan239°F(115°C)for10seconds,thecompressorwillstopand
restarttillT5islessthan194°F(90°C).
Temperatureprotectionofcompressor.
Checkwhetherthecompressordischargetemp.is
morethan239°F(115°C)?
No
Checkwhethertheconnectionisrightbetweencom-
pressordischargetemp.sensorandPCBaccordingto
wiringdiagrams?
Checkwhetherthe
refrigerantisleak.
Yes
Stopleakingandadd
refrigerant.
Yes
No
Correctthewiringconnection.
No
Yes
Measuretheresistancevalueofcompressordis-
chargetemp.sensor.Ifthevalueisnotnormalis
normalrefertotheAppendix2?
Replacethecompressor
dischargetemp.sensor.
No
Yes
ReplaceoutdoormainPCB.
No
Replacehighpressurevalveassy.