Lennox MPB012S4S

109
Error Code: E5
Description: Highorlowvoltageprotection
General Note: Anabnormalvoltageriseordropisdetectedbycheckingthespeciedvoltagedetectioncircuit.
Voltage protection
Checkthevoltageofoutdoorunitpower
supply,thevoltagebetween
L1andL2rangemin.187~253VACmax.
Yes
CheckwhetherthevoltageofIPMboard
PandNisnormal?277-356VDCfor
18-30KBtu/h;277-410VDCfor36KBtu/h.
No
Replacebridgerectiers,andthencheck
whetherthesystemoperatesnormally.
(Onlyfor4-zoneMPA036&MLA036
units)
No
ReplaceIPMboard,andthencheck
for normal unit operation.
No
Replaceoutdoormainboard.
Problem Solved.
Yes
Yes
Checktheprimarypowersupply.
No