My Goodman GMPN080 furnace has been acting strangely for several years now. After a concerted effort, I have determined that the stack over temp switch is opening at 140 degrees F, and not closing until it gets down to about
110 degrees F. This causes the gas valve to shut off. The controller tries three times to relight it, then shuts everything off for an hour, with a single LED flash code on the controller card.My question is: is this switch malfunctioning, or is 140F an unusually high temperature?
Thanks,
pf