A few weeks ago we went for a week-long camping trip. On the second night out, the furnace stops working; turns on, blows cold air for 20 seconds, shuts off. I tried everything the manual suggested about 30 times over - no change. Overnight temperatures were 4-5C, so we spent two freezing, sleepless nights, packed up camp and drove out to the nearest town in search of reception.
Once I had signal I found a bunch of online videos suggesting that the furnace's sail-switch may be the problem, and it needs to be removed and cleaned. Looking at the furnace, it seemed like the opening under the fridge was too small to pull the furnace out, and I'd have to remove the fridge to get access to the furnace. This seemed like a nightmare that I'd have to do at home, so I picked up some additional blankets and a portable propane heater, and we went to camp in our second (planned) location.
In camp, after a few bravery beers, I decided to give it a shot and see if I can pull out the furnace through the interior opening. As it happened, it came out with literally a millimetre of room to spare. I pulled off the propane line, both ducts, loosened electrical, removed mounting brackets, and out it came. Got access to the sail switch, and sure enough, it had the tiniest fluff of dog fur on it. Cleaned it off, re-assembled, furnace fired right up. This is what that process looked like in camp:
Winnebago cut a corner and didn't provide an exterior access panel to the furnace. Since I have zero interest in ever pulling out this furnace again, especially in camp, I decided to fix that. Ordered the "DOMETIC 33044 Small Furnace Access Door" and got to work this morning.
Made a template for my router (with the flush trim bit) to do the cut:
Ran into an unexpected stud towards the back of the trailer. I thought the studs here were 16" OC, but it looks like they're closer to 12". This stud wouldn't allow me to fit the flange of the inner trim piece that comes with the access panel, and since I'm not about to go cutting studs, I trimmed the flange, instead:
Hole fully cut. Note the random gaps in insulation. Clowns at Winnebago doing what they do!
Applied butyl tape and Sikaflex 291 to the inner flange, screwed it in, then installed the exterior panel door with the original exhaust.
Total 3 hours of work, but I'll never again have to pull out the furnace, so it's time well spent. I've also picked up a few spare sail switches should I ever need one in camp.
As a separate mini-project, I installed two ducts in the panel that hides the fridge. These are installed exactly where the fridge's own ventilation ducts are, and I think this should help overall fridge performance.
I removed the panel for this, and since it was originally nailed-in from the inside of the trailer (and I could no longer do that without pulling out the fridge), I installed a few rivnuts into the panel and screwed it in from the outside with those stainless, recessed bolts in the photo. Liberal use of Sikaflex 291 all over.