Thermostat for heat

[6845ct]

When I used the heat last in December on a 1,500 trip, there were no problems. Got in motorhome last week to excersize her, turned on the thermostat and the heat did not go on, didn't get the usual click. Hoping it is the thermostat. How can I check to find out if it is the thermostat that is no good?

[6845ct]

Wow! Didn't realize how involved that little thermostat is. Think I'll replace it to play it safe.

[enblethen]

Yes and no. What happens on some is the attenuator if equipped gets burnt and will not allow the current to flow. This is either a bar or a coil that allows you to adjust how close to set temperature the furnace runs. If equipped it is normally set about .80. You can slide the bar or turn the setting up or down slightly and the furnace will run.
Another problem is with the contacts. They get burnt and will not conduct. You could use an Emery board and clean them a little and they will still work.
Yes, the wires are small and somewhat delicate.
You can get a replacement mechanical for around $15.

[6845ct]

Yeah...I think it's old, 17-18 years old. Wires looked thin and very fragile and there was a coil. Carefully cleaned dust out of it while heat was running. We have rain/ice right now and more snow for tomorrow so I won't get back into RV till about Tuesday or Wednesday. Does it really matter if it's an old thermostat?

[enblethen]

Did you ever get the make and model of the thermostat?
I am still thinking you have an old mechanical thermostat. Just removing cover could make it work.

[6845ct]

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.

[enblethen]

did you find make and model of the thermostat?

[6845ct]

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.

[wa8yxm]

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.

[Dutch_12078]

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. 🙂

[dougrainer]

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

[chast]

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.

[enblethen]

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.

[Branson_in_Tucs]

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.

[chast]

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.