We are here in sunny but cold FL and using the furnace a lot more than in the past... of course when we need it the most it quits on us.
Initially I'd wake up in the morning to cold (yes we had propane) but if I cycled the thermostat off then on the furnace fired immediately. I should have taken this as sign of more ominous things to come.
Finally one morning it quit, nada, nothing, would not start up. So we cranked up the electric heaters we'd been using for supplemental heat anyway and I figured I'd look at it later that day. When later came I cycled the thermostat from off to on and the heat started again. Odd we thought. The next day we went through the same dance - heat stops in the night, won't start in the morning, starts again fine 12 hours later...
The third time around this block, not so lucky. The furnace just quit. The control board would make a slight hum when the thermostat went on but nothing else happened. Based on internet wisdom I checked all connections for being loose/corroded and wiggled all wires to see if I could convince the beast to work. Based on additional internet wisdom (backed by the Suburban manuals and schematics) I eliminated a few possible issues and decided this was over my head and called a service tech.
The tech agreed with all my diagnosis and proceeded to replace the control board - no change. Next he concluded my fan motor must be bad, but he directly applied 12V to the fan and it spun fine. Next suspicion was the thermostat (even though we could hear the control board hum/not-hum when the stat called for heat or not). So he jumpered out the thermostat - no change.
At this point he called the Suburban number and described the symptoms - they gave him the answer immediately. Any arm-chair techs here want to guess?
I'll put the answer in my next post.
Initially I'd wake up in the morning to cold (yes we had propane) but if I cycled the thermostat off then on the furnace fired immediately. I should have taken this as sign of more ominous things to come.
Finally one morning it quit, nada, nothing, would not start up. So we cranked up the electric heaters we'd been using for supplemental heat anyway and I figured I'd look at it later that day. When later came I cycled the thermostat from off to on and the heat started again. Odd we thought. The next day we went through the same dance - heat stops in the night, won't start in the morning, starts again fine 12 hours later...
The third time around this block, not so lucky. The furnace just quit. The control board would make a slight hum when the thermostat went on but nothing else happened. Based on internet wisdom I checked all connections for being loose/corroded and wiggled all wires to see if I could convince the beast to work. Based on additional internet wisdom (backed by the Suburban manuals and schematics) I eliminated a few possible issues and decided this was over my head and called a service tech.
The tech agreed with all my diagnosis and proceeded to replace the control board - no change. Next he concluded my fan motor must be bad, but he directly applied 12V to the fan and it spun fine. Next suspicion was the thermostat (even though we could hear the control board hum/not-hum when the stat called for heat or not). So he jumpered out the thermostat - no change.
At this point he called the Suburban number and described the symptoms - they gave him the answer immediately. Any arm-chair techs here want to guess?
I'll put the answer in my next post.