Heat Won't Cut Off

Just plugged in the electric and the heater/fan is running. Turned heat and fan to "off". Still running. Any suggestions?

Have you tried recycling the on/off switch? Is it just the fan, or does the heat also come on? Is there a "fan only" switch on your thermostat? You may have to disconnect the thermostat (with power off) to determine if it is defective.

I have tried recycling through Off, Cool, Heat, and back to Off. I've done this a few times. The fan has a selection for Hi, Lo, and Off. It is set to Off. There is no hot air (the thermostat is set to it's lowest setting 50 degrees). But cool air is blowing outside at the furnace exhaust. So I would say the furnace is running but blowing cold air. I am on household current.

The furnace runs on 12 volt. If it starts running when you plug in, I would look at your batteries. You may have a bad one or they are so low that you may not be getting full voltage to the furnace to operate it correctly.

Check the thermostat just had to replace ours on a 2011 Sundance 3100ES The furnace or fan would not come on.

The same exact thing happened to me last week
We are on the road and had cold nights and the batteries on the unit went down
The furnace fan brought them down as low as can be and stoped.

when I started the truck to recharge, the furnace fan kept running,
so I had to pull the 20Amp Fuse and disconnect.
Even with the batteries showing full charging the fan stayed on.

I had only 2 trailer batteries so I went and bought a new one and connected it
Put the fuse back on the furnace and the fan didn't start so switched it on and it has been perfect since.

I was all discouraged that the furnace needed repair but It was saved. Now I have 3 brand new batteries on the unit
and everything is well.

I noticed tonight that the fridge stop working while one propane tank emptied and auto switched,
must be that the furnace is taking to much for the auto switch valve supply both.
Switched the propane tank to the full tank and everything is well.