Originally Posted by jimdelora
My wife and I are 70+ years old, living in AL, and maybe due to Covid 19 we want to get out of the house so we bought a 2019 Cougar RBS. Plan on going to the FL panhandle in 2 days to spend a week. As the weather has turned cold...in the 30's, I decided I better turn on the furnace. With unit on rear AC, Gas, Auto, it starts up and runs for about 30 seconds (plus the AC fan blows), it then shuts off. As we are real novices we need some info as to how to get the furnace working...don't want to carry a heater along. Excited about learning this new way of life but currently frustrated. HELP!
Have the same rig, had the same problem.
Easy problem: AC fan comes on. This is due to a ridiculous human interface
on the part of Dometic:
Dometic AC fans, when in Heat mode, turn off when set to "Auto" speed.
When the fan speed is set to “Off”, the AC fans run at low speed.
Get it? "Off" means "on low," what could be easier?
Harder problem: You say it runs for 30 seconds and shuts off. This isn't necessarily
a sail switch problem (according to the experts here) but I will say that every time I have seen this behavior reported either in my own rig or on this forum, it has been
a sail switch problem. Another "tell" is that you hear the heater fan running for 30 seconds before giving up, but you never hear the snap-snap-snap of the igniter trying to ignite the gas... because the sail switch is telling it the heater fan isn't running, so the igniter won't even try.
I've had the sail switch replaced (or de-fouled) twice on my rig in barely two years. The first time, it had been fouled by construction debris (sawdust and styro chips). The second time, it just went bad.
The furnace in the 26RBS is particularly nasty to access, as there is no outer skin port. It has to be extracted from underneath the fridge to be worked on, then installed into a custom bench jig to be tested before reinstallation.
The warranty on Dometic parts is two years. If you hurry, you may be able to get your sail switch fixed under warranty.
I'll also mention: given the unreliability I have encountered with this furnace, I don't leave home without a spare electric heater under the dinette, and I haven't been sorry. My small cube heater, paired with a Lux plug-in thermostat adapter, kept the entire cabin comfortable on a recent Flagstaff-area trip when our sail switch gave up the ghost most recently.