Furnace trouble

[Dragonfly70]

We have a 2017 Hemisphere 5th wheel. Right now temps are such that we are running our furnace when we go to bed, but have the windows open during the day. The past few nights, around 2am, the furnace stops blowing hot air, and the main AC starts clicking. Things we've checked:
✅ Propane tanks aren't empty
✅ No smell of propane
✅ The thermostat for the bedroom is off (doesn't control the furnace)
✅ The main thermostat has been reset. Doesn't change the problem.
✅ The thermostat fan control is set to auto.

If we leave the heater off for a while, it comes back on and works fine. But it's a bit of a problem having to turn it off when the AC starts clicking, and we usually fall back to sleep without waiting to see if it come back on. Unfortunately that means we wake up to the RV being between 58-62. I want this fixed before real cold weather hits. Ideas for other things we can check before calling a repairman?

[llr]

Are you plugged in? Or running off battery? If battery I suspect low voltage as the fan is a big draw.

air conditioner clicking sounds real odd. Is it possible the clicking is just not heard with the furnace on and is not related?

What AC and furnace do you have?

[Dragonfly70]

We are plugged in. The furnace is from Suburban and the AC & thermostat are Dometic. Have checked the exterior exhaust as well, and no blockage there. I did some more searching and suspect it might be debris/dog hair blocking the sail switch. There is no exterior access to the furnace, though, so need to figure out where we can access the furnace to check.
The AC clicking happens for some reason when the furnace doesn't ignite. When we ran out of propane, it did the same thing.

[SeaDog]

Welcome to the forum its a great place to get your questions answered.

[{Tpc}]

I know its been awhile but the clicking is more than likely the ignitor trying to ignite than the AC unit? Since you said you heard this when you also ran out of propane, this is what I would expect.

I can't imagine it a result of a low battery but i am making the assumption your connected to shore power.

I'm wondering if there is a dirty sensor somewhere. Or if there isn't some recurrent air bubble in the line somehow, maybe its caused by higher day temps and colder night temps?

I would find the furthest thing away from your propane tanks (usually an outside connection for a grill) and try to ignite that. Make sure you have good flow to that point (grill works first try, etc), and see if the problem persists. Maybe you have a faulty automatic changeover switch and when it gets cold something happens?

To me though, it sounds like the furnace stops getting propane at some point in the night and starts trying to ignite, which doesn't work until you turn it off and back on. Maybe its an error on a control board or something, and that action clears it?

[Raven5280]

my 2022 FSX is currently getting it's furnace fixed, sounds similar to your issue. Unit will heat to temp and will not light once temperature drops below whats set on the thermostat. It clickes while trying to light the propane and then shuts down. If I turn the thermostat off wait a few mins and back on it fires and heats up and back to clicking once the temp drops. My issue is covered by warrantee but the shop said it related to one of the temperature sensors in furnace.