Furnace overshoots set-point, and will not restart

[Dr Hillbilly]

I woke up to find my RV at 81 degrees F with the furnace still running and the set-point at 67 degrees F. The furnace would not shut off with the thermostat control so I shut the propane off. The blower then shut off after cooling. Now the furnace will not attempt to restart:
12V is good (I am running on a generator and the battery measures 13.6V)
the fuse is not blown and the breaker is OK as other items on the same circuit work
Propane is full and I am heating with the range as the heater is dead

Any ideas?

[Country Campers]

What model RV? What brand or model of furnace?

Brian

[Scott'n'Wendy]

First...heating with the range can kill you...... CO.
And along with Brian's questions, type of t-stat.

[Dr Hillbilly]

I have a Grand Design Imagine with a Suburban furnace.
The control-card (which I suspect) is the 06-237591-001
I have 13.6 volts to the on-off switch, and to the yellow and blue connectors on the card.

I have a propane sensor but do not trust it, and only heat with the range when I can watch it.
There are more than enough air-leaks in the trailer to prevent a build up of CO2! And the flame is blue and clean so CO1 should not be an issue.

[Scott'n'Wendy]

On the fail to restart, Does the fan start? If so, do you hear the ignitor trying shortly after?

What I'm thinking is we need to try and determine if you have a t-stat problem or a furnace control board problem.

[Dr Hillbilly]

the fan does not start and no attempt at ignition

[Scott'n'Wendy]

Then I think you need to jumper the t-stat wires to initiate a call for heat. Difficult to call if it's tstat or furnace board yet.

If the furnace than tries to start, I say you have a tstat problem...if it doesn't, furnace board problem.

[Dr Hillbilly]

when I increase the temp setting on the thermostat the "heat" logo blinks four times. Does that indicate a call for heat?

[Country Campers]

What is the brand of thermostat?

Brian

[Dr Hillbilly]

it is airxcel

[Jlawles2]

You might try pulling the t-stat off the wall and verifying that the connector on the back is properly seated. there have been a few reported issues with the connector coming lose and creating several intermittent issues.

Most likely you will need to pry the stat out of the housing if it does not lift straight up to remove (documented in the forum several places).

[Country Campers]

I would also suggest cutting all power to the furnace and the thermostat, this may reset everything and get it working. Turning off the propane to force the furnace to shut off may have caused a fault. From the description of the furnace overheating the coach you may have a faulty thermostat. You may also try to remove the thermostat and figure out which wire turns the furnace on and jump that to see if the furnace will run, this could mean that the thermostat is bad.

Brian

[Scott'n'Wendy]

when I increase the temp setting on the thermostat the "heat" logo blinks four times. Does that indicate a call for heat?

Well it is supposed to mean that, but if it's faulty, not necessarily. The only way to guarantee you are calling for heat is to jumper the wires of the tstat together. You need the manual of your tstat to know which are the correct two to jumper together. Unless there are only two wires.....

[Dr Hillbilly]

I downloaded the thermostat manual, determined which wires to jumper, and the heater started!
I now have a new thermostat on order, and just might have heat tomorrow...

Thanks for all of the help!

[Jlawles2]

In the mean time, try plugging the thermostat back in and see if it works until you get the new one. Now that you have it off the wall, should the heater stick again, it's a simple unplug.