Lennox MPB012S4S

106
Error Code: E3
Description: CommunicationerrorbetweenoutdoorunitmaincontrolandIPM.
General Note: PCBmainchipdoesnotreceivefeedbackfromIPMduring60seconds.
CommunicationmalfunctionbetweenIPM
board and outdoor main board.
IsthereatleastoneLEDintheIPM
boardlight?
No
CheckthesignalwirebetweentheIPM
moduleandthemainboard,isitcon-
nectedcorrectly?
No
Reconnectandretry.Doeserrorstill
display?
Yes
ReplaceIPMboard,andthencheck
whetherthesystemoperatesnormally.
No
Replaceoutdoormainboard,andthen
checkwhetherthesystemoperates
normally.
No
Replacetheelectriccontrolbox.
Problem Solved.
Yes
Yes
No
Yes
Yes
Yes