Atwood Heater won't turn off???

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butchiiii

Well-known member
Joined
Sep 8, 2014
Posts
347
Location
Los Angeles
Okay I finally got to go back to our TT to check out the furnace issue. We got to our destination
and I set up. Turned on the propane and 5 minutes later the furnace comes on and I can't turn it off.
The Dometic LCD single zone thermostat was in the off position at the time. I cycled to the heat setting and set the
temp way below the temp that it would call for heat but it still would not shut off. So I turned of the propane
and after failing to light it finally shut down.  Turned the propane back on and it stayed off until about
2am in the morning it came on by itself again with the thermostat in the off position and the inside temp
way above any need for heat being called.aWhat could possibly be the problem. Thermostat? I did not see anyththing
in Gary's trouble shooting guide that referenced this problem.
Help needed. TIA
 
Makes and models would be helpful!! Has this thermostat been changed or is it the original??

Take the cover off the thermostat and locate the "I need heat"* wire. You may have to remove the thermostat from the wall and find the wire in question. (It may be spliced to a heavier wire behind the thermostat). Disconnect or unplug it it and see if the problem is still there. If it is, then you have eliminated the thermostat as a source. If it is not, do the same at the furnace end. If the problem reoccurs, It would likely be the furnace control board.

*To demand heat, the thermostat applies 12V to this wire, you can also measure with a voltmeter to see if there is a constant 12V on this wire when there should not be.
 
Hi Stu,
It is an Atwood AFMD20 furnance. 20k btu. The thermostat is original Dometic LCD Single zone heat/cool series 3313192.xxx.
I will try the tests that you suggested.
Thanks
 

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