Here's the story, Tuesday night/Wednesday morning our power went out at least once. Yesterday the furnace was running as I was leaving for work. As I am want to do I reached over and turned the furnace off with the thermostat as I was walking out the door. Later when my wife came home she thought the furnace was on because the main blower was running. After a while she realized the furnace was not on at the thermostat, and she turned it on at the thermostat. Needless to say, even though the blower was running, no heat.
After I came home I started digging into it. I turned off the thermostat and removed it from the base and turned off the furnace at the switch by the furnace. I waited a few minutes then turned on the switch. The main blower came back on. I opened the furnace and lightly tapped the relays on the circuit board, thinking it was a stuck relay. I closed up the furnace and turned everything back on. It worked for one start up cycle, and then the main blower stayed on. I said the heck with it and went to bed. This afternoon I got a new circuit board and replaced it. After replacing the board I had to cycle the gas valve to get the burners working, which I'm pretty sure is normal. Everything was fine for one cycle. I had to cycle the gas valve in order to get the furnace to light for the second cycle. Now the darn exhaust fan won't turn off. The burners and main fan cycle fine.
Any help would be appreciated.
Oh, the furnace is an older Armstrong sx80.
Thanks.
After I came home I started digging into it. I turned off the thermostat and removed it from the base and turned off the furnace at the switch by the furnace. I waited a few minutes then turned on the switch. The main blower came back on. I opened the furnace and lightly tapped the relays on the circuit board, thinking it was a stuck relay. I closed up the furnace and turned everything back on. It worked for one start up cycle, and then the main blower stayed on. I said the heck with it and went to bed. This afternoon I got a new circuit board and replaced it. After replacing the board I had to cycle the gas valve to get the burners working, which I'm pretty sure is normal. Everything was fine for one cycle. I had to cycle the gas valve in order to get the furnace to light for the second cycle. Now the darn exhaust fan won't turn off. The burners and main fan cycle fine.
Any help would be appreciated.
Oh, the furnace is an older Armstrong sx80.
Thanks.