dougrainer wrote:
You have replaced a couple of tstats in the past few years? THAT is NOT normal. Tstats rarely fail. So, your problem was there prior and now it is there for good. When the fan comes ON, The sail switch closes and sends power thru the Hi limit to the control board. Now, without the brand and model, we can only guess now. It is not uncommon for certain Atwoods the wire going to the hi limit switch touch the burner casing and melt and short. THAT would be my first thing to look and verify. Gas Valves shorting out? I have not seen such a thing in over 25 years and I have worked on thousands of furnaces in that time. Possible corrosion on the Control board. Most furnaces have a circuit breaker to prevent shorts from burning out tstats and such. Doug
Problem solved. I think you were right. Found a mobile tech guy in Louisville KY who worked us in between jobs, and found a yellow wire that chaffed, taped it up and reinstalled another extra thermostat I had laying around, all in about 15 minutes, at a VERY reasonable price. Both I and my furnace guy friend inMI had looked and never saw it. So happy to have a working furnace again.
If anyone needs him, the name of his company is B&S Mobile RV Service and Repair, in Louisville.
Thanks EVERYONE for the suggestions and help.
