heater fan runs with no heater turned on

[careyc]

I have a 4wheel pickup pop up.
when the heater is off ( many hrs) the fan runs intermittly. it Will shut off but turns back on shortly.
do I need a new thermostat? its a emerson #1E78-140 if so is it easy to replace?
or can the contacts be cleaned (where&How)??
Mine has two batteries and the new ones have three, is there a reason for that?

 

[Kirk]

The thermostat does turn the furnace on, starting with the blower that both moves air through the camper to warm it and also air from outside through the combustion chamber for the propane to burn. I would highly suspect a problem with your thermostat or the wires to it. If it were me, I would lift one of the wires from the thermostat first, just to verify that it turns the furnace lower off.

As to the number of batteries, they probably want to supply more power for camping without outside electricity.

 

[careyc]

The thermostat does turn the furnace on, starting with the blower that both moves air through the camper to warm it and also air from outside through the combustion chamber for the propane to burn. I would highly suspect a problem with your thermostat or the wires to it. If it were me, I would lift one of the wires from the thermostat first, just to verify that it turns the furnace lower off.

As to the number of batteries, they probably want to supply more power for camping without outside electricity.

i'll give it a try thank you

 

[Alontheway]

Need more info...
Your thermostat, no matter how complex it is, does two things. Turn on or turn off. It is just a switch. It either connects the circuit or disconnects it, like a light switch, on or off.
The fan is operated by the furnace itself. The fan should run first before the propane valve is open and the burner lit. This is to run out any possible propane gas that might have leaked and accumulated around the burner to prevent a boom boom, and might be other reasons too.
If the propane pressure is too low then the propane valve will not open and the fan will turn itself back off (the furnace turns the fan off) for a time period. It might try again later and just keep trying, BUT the thermostat must be in the ON position or nothing will happen, so check for a short that might be keeping the thermostat on anywhere between the stat and the furnace. If you can get to it then unhook the thermostat wire at the furnace to be sure that a short is not keeping it on first.

 

[unni]

I agree with Kirk to make sure, but I think you are thinking in the right direction. I could be the thermostat.