A.O. Smith 310 - Page 24

TroubleshootingGuide
24|Page
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CHECKINGTHEOVERHEATCUTOFFFUSE(OH CF):
1) LocatethewhiteOHCFwhichwrapsaround
theheatexchanger.
2) Findthewhiteclipattheendofthetwoblue 
braidedwirescomingfromtheOHCF.
3) Unplugtheconnection.
4) TestforcontinuityattheendoftheOHCF
withanohmmeter.Ifthereiscontinuity,the
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OHCFisstillintact.Reconnecttheplug.If
thereisnocontinuity,theOHCFhasbeen
compromised.Ifcompromised,contactthe
TechnicalServiceDepartmentforfurther
assistance.
5) Ifanohmmeterisnotavailable,jumptheplugconnectionontheoppositesideoftheOHCF
withawire,paperclip,
orothermetalmaterial.
6) Restorepowerandtestunit.Beverycautiouswiththisstep.Donottouchthejumperor
otherelectricalcomponents.
7) Iftheunitfiresup,itshowsthattheOHCFhasbeencompromisedandtheproblemwaswith
theOHCF.Ifso,contacttheTechnical
ServiceDepartmentforfurtherassistance.Iftheunit
doesnotfireup,itshowsthatthecauseofthe111or121errorcodeissomethingelse.
Continuewiththe111or121errorcodesectionsofthisguideforfurthertroubleshooting. 
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Figure23
Figure22