I seem to have picked up a pesky poltergeist while at the Baker Hotel in Mineral Wells, TX!
For no reason my furnace comes on, and stays on till I pull the hot wire from the electric motor. It's a Hydro-Flame Mod#:8531-III SN#0080356
After a while, I can replace the hot wire and it functions normally and can be controlled from the thermostat.
I suspect the relay mounted on the motor housing.
PS, As we speak it is learning new tricks; now it turns on and off all by it self, Op there it goes again!
I have turned of the internal rocker switch which keeps the propane from firing up, it's hot enough here in TX.