Lennox MMDA048S4-*P - Page 149

149
Error Code: P6
Description: Compressorhigh-pressureorlow-pressureswitchopen
General Note: Ifthesamplingvoltageofpressureswitchisnot5V,theLEDwilldisplaythefailure.
Testeachpressureswitchseparatelyfollowingtheseowcharts.
Checkwiringconnectionsbetweenhighpressure
switchandmainPCB.
Yes
DetermineifHighpressureswitchisfaulty.
Method:Disconnecttheplug.Measuretheresistance
ofthehighpressureprotector,iftheprotectorisnormal
thevalueis0.
Yes
Makenecessarycorrections.
No
Replacehighpressureprotectionswitch.
No
Checktheoutdoorambienttemperature.Theoutdoor
ambienttemperatureshouldnotbehigherthan50°C
or122°F.
No
Stoptheunit.
Yes
Checkiftheoutdoorunitventilationisgood
Yes
Makecorrectionstoallowforproper
ventilation
No
Checkiftheoutdoorfanrunsproperly
SeeFaultcodeE8toproperlydiagnose
outdoor fan motor.
No
Yes
Checkoutdoorcoils.Theoutdoorunitcoilsshouldbe
clean and free of any debris.
Clean outdoor coils.
Yes
No
Replaceoutdoormainboard.
No
CheckwhethertherefrigerantsystemisOK.