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Atwood Furnace Thermostat Short

Furnace Heater electrical

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#1 FiveMileFWC



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Posted 15 October 2020 - 01:18 AM

I recently picked up a 2000 FWC Grandby that I've been loving. The furnace, however, has been a bit of an enigma. The fan starts, but the spark and fire of the propane heat has been intermittent at best.


After some digging, I noticed that the anticipator wire on the thermostat was fried, enough to where when you clicked the heat on, the wire would glow red hot and smoke. I figured "maybe it's a problem with an old t-stat"... so I bought the newer Dometic branded exact replaced off Amazon.


Today, I installed the new thermostat and instantly fried the anticipator wire in half. The furnace still kicks on (which is surprising), but the anticipator wire and metal arm on the thermostat are red-hot... enough to burn your finger on touch.


Does anyone here have any suggestions on what might be causing the short? (I assume somewhere wires are shorting but don't know where to start looking.)


Attached is a photo of the old friend thermostat anticipator wire.

Edited by FiveMileFWC, 21 October 2020 - 12:46 AM.

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#2 FiveMileFWC



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Posted 04 January 2021 - 04:46 PM



This service manual was a huge help: http://techsupport.p...Manual-2007.pdf


According to the manual, a friend anticipator wire / thermostat can either be caused by a dead short, or from a failed time delay relay. After inspecting the wiring that I could see, and not hearing or seeing a short when power was applied to the t-stat, I determined it was most likely the TDR.


I went ahead and installed this TDR: https://www.amazon.c...0?ie=UTF8&psc=1


And this new thermostat: https://www.amazon.c...0?ie=UTF8&psc=1


...and we're back in action!

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#3 veryactivelife


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Posted 05 January 2021 - 04:30 PM

Good to hear that you sorted this out and thanks for posting the fix.

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