Thermostat for heat

Hi--it is a bit more involved that you stated. If the battery(ies) are not up, there may be insufficient voltage to fire it off. Is the motorhome plugged in? If not, try it plugged in. If you push up the thermostat and the heater runs, it is probably not the thermostat. Let us know what you find.

One check you can do, is remove your cover and check your fuse. My fuse looked good, I took it out and placed it back and every thing was fine.

Mechanical thermostats have no fuse to check. Electronic thermostat have fuse and some have batteries.
If it is a small mechanical thermostat, remove cover, locate the two wires going to furnace. Connect them together. Fan should start, then in about 15-20 seconds the burner should start. Separate the two wires and the furnace should go into shut down mode and then shut completely off.
Make sure you have 12 volt DC turned on and batteries are up or main engine is running providing power to the coach system.
Make and model of rig would help.
Make and model of thermostat and furnace.

If all else fails, remove the two wires from the thermostat (you may have to remove the thermostat from the wall) and twist them together. This will bypass the thermostat and tell the furnace to come on.

You need to state year/brand/model RV. Also the Roof AC brand and model if you know it. The TYPE wall tstat. Does it control all AC/furnace functions or just the furnace? Describe what the wall tstat looks like if you cannot get brand/model number. ONLY RVP(Coleman) tstats have a fuse on the tstat. The odds are you do NOT have a bad tstat. Rarely does a tstat fail, it is usually something else and in your case probably at the furnace itself. Doug

I agree with Doug that tstats rarely fail, although I did have a Duo-Therm mechanical stat fail with a burnt heat anticipator printed circuit board once. Hard to believe how bad that postage stamp sized board smelled when it cooked! That failure did make for a good excuse for upgrading both stats in the coach to Honeywell programmable digitals though. :)

If you have a whole bunch of wires hooked to a heat/cool T-Stat.. Look for Blue, may or may not be the right wires, but Look for blue.

Use a meter to find 12 volts (reference to ground) that will be one of the wires, make sure you mark that wire and the screw it attaches to (on a multi wire unit)

The other blue wires is the other thermostat lead,,, IF, that is they used blue which there is never a guarantee on.

Thank you for all responses. Our RV is nothing spectacular...just a 98 Coachmen Mirada that's paid off and gets us were we want to explore for the past 12 years. I'll check the thermostat wiring and if that doesn't work I'll get additional info for help. Let you know tomorrow.

did you find make and model of the thermostat?

OK....there is a gremlin in my coachmen. RV was plugged in the last time I tried the heat...checked the microwave to see if it was on and it was but heat didn't work. Pulled cover off of thermostat today and turned it on. The heat worked! Maybe I jolted something...who knows. At least I have an idea if anything goes wrong with the heater what to do. RV has been good to us for 12 years so I am waiting for things to start going on it. Thank you everyone for your suggestions.