Furnace won't start - 2019 Globetrotter

[tgoedken]

Furnace was operating just fine - until late last night. Now, even though the thermostat is calling for heat, the furnace will not start. I have two A/C units with heat pumps - they work on same thermostat and will start and provide heat. But the FURN and FAN settings on the thermostat just won't come on.

We are on 50AMP shore power and batteries are fully charged.

I looked at previous posts and and replaced the 15AMP fuse for fan/furn - still nothing.

Ready to take the cover off the outside - but wnated to post to see if there are other things to do.

2019 Globetrotter 27FB

Thx

Tom

[GCinSC2]

Tom

Does the blower on the furnace turn on?

Outside cover do you see a red fault code light on control board is it flashing?

Model number of furnace can also prevent false leads etc.

Gary

[mojo]

Try turning off the propane, wait 5 minutes and turn back on slowly. Turning on quickly can often cause a lock out on the pressure regulator.

[tgoedken]

Thanks so much for repsonses.

No - the blower does not turn on.

Model number = AFMD25 by Atwood.

I removed the cover - there is ONE red flash each 3 seconds - indicating "Limit Switch/Airflow problems" per the manual.

I have shut down the furnace, turned thermostat to off, closed gas supply - then opened gas supply slowly, truned furnace back on and set thermostsat to call for heat - I hear an audible "click", then the red light flashes.

Any suggestions appreciated.

Tom

[tgoedken]

Still new to posts/repies. I enterred a "reply" in this thread

[GCinSC2]

Tom

That fault code light is first place to start. I’ve found lots of factory service manuals here https://myrvworks.com/manuals/ I’m away from pc so a bit harder to search but look for troubleshooting guides in that link. Darren has a YouTube channel and has covered furnaces extensively.

Gary

[tgoedken]

Thanks - will get busy on it!

[AndrewF]

This happened to me last year on my 2020 GT. Turned out the control board for the furnace was bad. I had it replaced under warranty

[GCinSC2]

Something that’s pretty helpful with the Atwood or Dometic service manuals is they use diagnostic info to go from symptom to likely component to check and what to look for.

And the furnace has a very specific starting sequence. Observing which step isn’t happening is a big clue to diagnosis and repairs. And hopefully leaving the parts cannon unfired.

[MSL]

I had a similar situation with my 2019 Sport 22 when it was 2 years old; worked fine until then. The code led me to the sail switch. I checked it with continuity, and it looked good. However, when I checked with voltage, it showed the connection was bad. I removed the switch and opened it up, even though the contacts looked good, I sanded them and put it back together; still same problem. I removed the switch again and bent the "sail" portion and got it to work properly.

You have to be careful when bending the sail. The switch has to be open when the fan is off and fully closed when the fan is on. It took me a couple of tries.

Photo of switch assembly attached, but it doesn't show the view needed to see the "sail" portion.

My fix worked for months until my first warranty trip to Jackson City. I asked if they would just give me a new one in case my sanded contacts failed; they wouldn't, but they did install a new switch, which has worked for the past 1 1/2 years.

Good luck, Mark

[tgoedken]

Thanks all. I have an appointment now with AS service. I’m not comfortable with changing a switch - which it appears to be

So, blankets and we will use the Heat Pumps.

Thx all!!

[hhendrix]

The sail switch (good picture above) can get dirt and lint in the lever area and prevent the contacts from working. Very easy to remove and check. The sail switch ensures the fan is on before the ignition, otherwise the furnace can overheat or worse.

[hhendrix]

BTW my post says it is 1:38 am but I'm in Cambodia and it is 3:43 pm

[tgoedken]

All - Final update.

It ended up being a board replacment - there was one connection that was fried.

Furnace is now working great!

Thanks All!!

Tom