1981 Bigfoot furnace problem

[alliestarr]

Edit: I meant to post this in the problem solving thread so if you see it twice, that's why!

So we have a 1981 Bigfoot 17 that we are currently having a furnace problem with. It's worked great in the past (albeit the fan is pretty loud and it can be a pain to get the pilot light lit...but I don't think this is uncommon for this age of Bigfoot).

The furnace started right about several weeks ago but when we went to turn it on last week, nothing. The pilot light is on and the thermostat makes the 'click sound' when the lever is pushed up, but the furnace just isn't powering up. It isn't a problem with the battery - we have solar panels that had the battery nice and charged up last week, and today we are plugged in. We've checked the wiring on the thermostat (the ones we can see) and nothing appears to be loose. Both propane tanks are full and we've had no problem lighting the stove or pilot lights on oven and fridge.

We haven't taken the back panel off yet to investigate from that angle, but I am just wondering if anyone has any insight or tips! We aren't experts but have done a pretty good of troubleshooting other problems and figuring them out, but this is one is stumping us.

Thanks in advance!
Allie

[South Coast Stu]

Do you know the make and model? I would start by finding the manual. Most manuals have a step-by-step trouble shooting guide for that particular appliance. Good luck!

[thrifty bill]

+10 above. Its not a Bigfoot furnace, its a Suburban, or Atwood, or whatever other brand it might be. As such, troubleshooting the brand of furnace, rather than the brand of trailer, is optimal. Many appliance manuals are in the document center. and unless you bought the trailer new, in 40 years there is certainly a chance that furnace is not original (replaced/installed by a prior owner).

[fishinjimi]

it may be a bad Thermocouple or a sail switch

[alliestarr]

Thanks, everyone!

And the mystery continues...We stopped on top of a pass yesterday to use the bathroom and as soon as I opened the door, I heard the furnace fan running, which it hadn't done in several weeks now! The thermostat wasn't all the way off and it was 40 degrees inside, so I guess the sensor finally kicked on.

When we got to our spot, we lit the pilot light and did all the usual things. Nothing. Then about an hour later, all of a sudden the damn thing kicked on and started blowing warm air. Fixed! Turned it down to a reasonable temp for the night and it never kicked on, even tho it was about 35. Super frustrating. Turn the thermostat off and on a couple of times and just let it be this morning...About an hour later it kicks on and starts working like a champ again.

It makes no sense and is completely illogical, but, apparently, it does still work..just has a mind of its own.

The thermocouple was one thing I thought might be going on..but now we have no idea. Gotta love the old Bigfoots!

[canyon Rafter]

Frustrating for sure! I had a sail switch that would work intermittently, it would work sometimes and then not work at all other times. I Replaced the sail switch and all is good now. Sail switch was under 15 bucks! I would start there, remove the switch and have it tested, if it is still good there are three main things that usually malfunction with rv furnaces. Circuit board(not common and most expensive),high limit switch, and most common and turned out to be my broken part is the sail switch.