Heat not coming on

[goodworkmax]

2001 Thor Chateau 31 with a Coleman Mach thermostat. Full tank of Propane. Heat was working fine. Now all of a sudden won't kick on and of course we're about to leave on a week long trip in February. Any ideas?

[bobndot]

Hmm, very spooky. Things like that usually happen in Salem. 🙂

[goodworkmax]

OK. So, mystery solved AND not solved. The switch I had found near the galley was for the water heater so that was me being dumb. However, here's where it gets strange. I opened up the panel on the outside of the rig where the furnace lives. 4 screws I had never taken off. intention was to blow compressed air around and check any leads I might find in there since all the fuses and breakers inside were all good. In there I found an on/off toggle switch and a 10amp reset button. The toggle was switched to "off" position. Now I swear to you that I have never been inside this compartment and 3 weeks ago the heat worked fine. But when I switched the toggle to "on", the **** thing kicked on like the day it was installed. I went in and tested the thermostat and it's working perfectly. What I cannot explain is how that toggle could have been switched to the off position. Absolute mystery. And I feel like an ******* for wasting all of your precious time. Thank you for trying to help. I guess the lesson is a reminder to check the easy stuff first.

[Bordercollie]

I once found a loose 12 volt connection at the thermostat. Also found a loose screw connection at the fuse panel. Fan must get 12 volts DC to run. I wouldn't attempt to run furnace without fan running, may be dangerous or damage furnace.

[enblethen]

You have a very old thermostat. You might watch this Utube.
Upgrade thermostat
This link Eldon shows wiring diagram better than Utube.
Eldon

[enblethen]

Picture works for me!
Note the sentence on the bottom about an internal fuse.

[goodworkmax]

couldn't find it there but here is a picture of it:

[enblethen]

Use this link to try and identify your thermostat.
Coleman thermostats
It is possible that someone added the switch for safety.

[goodworkmax]

I did not find a model for the thermostat. just says Coleman Mach on the front. I believe it does control the AC as well yes. I only just purchased this unit a month ago and it's been so cold here (boston area) that I never tested the AC. But the heat worked great 3 weeks ago.

[enblethen]

Sounds like someone has bypassed the thermostat!
Did you find model of the thermostat? Does the thermostat control the AC as well?

[goodworkmax]

OK. so I checked the fuses. One on the back of the Coleman Mach thermostat and one labeled "furnace" in the fuse box next to the breakers under the back bed. pulled, checked, cleaned. all good. I discovered that there is a switch next to the sofa against the kitchen cabinet which when turned on, I can hear the furnace light up and I can hear the burner going and warm exhaust coming from the exhaust vent outside. This turns on no matter what the thermostat is set at. But the fan never kicks on.

I am currently plugged into shore power. Furnace is Atwood 8500-IV I believe.

[midnightsadie]

don,t just look at the fuse ,pull and clean. some times they get dirty.

[enblethen]

Does the fan start? If no check the furnace for 12 volts DC. Check fuse in 12 volt DC distribution panel located normally adjacent to the 120 volt circuit breakers. Yes, are you on shore power or batteries? If on batteries are they charged?
Does stove top work or water heater? If yes, your sail switch may not be closing due to debris. Blow furnace out with high air pressure or canned air.
Make and model of furnace? What model of thermostat?

[goodworkmax]

I pulled the Thermostat but there are no batteries in there.

[Dick_B]

Thermostat batteries?