Furnace keeps running and running and...

[marcdohc]

Hello all, I have a 2004 Coachmen Mirada 30QB with a Atwood Furnace model #8531-1V-DCLP and a Dometic thermostat and AC. Heres my problem. We set the heat at 67* or so. The heat was not coming on till it was around 57* and then it would stay on till it was 80*. I purchased a new thermostat and wallha! it worked as it should, for 1 night. Now when the heat comes on it reaches temperature you her the furnace shut the flame out but the fan keeps going. Typically the fan will run for a minute or two and then shut off. Now the fan stays on and after 3 or 4 minutes the flame kicks on again. I also heard some light tapping sound coming from the heater after the flame would shut off. Does this sound like a part failure I could swap? What do you think? Thanks for reading, Marcdohc

[clyon51]

It sounds like the time delay relay is keeping the fan running until the next heat cycle. Heres some furnace troubleshooting tips

http://www.rverscorner.com/furnace1.html

[Papa_Jim]

Originally Posted by marcdohc

Now when the heat comes on it reaches temperature you her the furnace shut the flame out but the fan keeps going. Typically the fan will run for a minute or two and then shut off. Now the fan stays on and after 3 or 4 minutes the flame kicks on again. I also heard some light tapping sound coming from the heater after the flame would shut off. Thanks for reading, Marcdohc

I had exactly the same experience with my Suburban furnace a couple of years ago. I absolutely could not figure out what was causing it.

I was helped by a man that had experienced this before. The problem was the propane regulator at the propane tank. It was clogged with the oil they use in the propane (I forget the name of that oil, but I guess it doesn't matter). You can remove the regulator and clean it with carburetor cleaner. However, when I removed it I took it into our local RV place, and they had a brand spanking new one for $25.00.

That solved the problem.