Dometic furnace won’t ignite

[Bporourke2]

So my furnace on my 2019 Alpine 3700FL will not ignite. It’s one of the Dometic 35K BTU doorless units. Anyways, when I set the temp high enough to turn on the propane furnace, the blower will activate for 30 seconds but the burner will not come on and then the whole unit shuts down. I was fiddling with it yesterday and I got the burner to come on after power cycling the furnace via the power switch in the body about 10 times. When the temp hit the set point and turned off, the burner did not come on the next time it dipped below the set point.

I do have the in command system as well and I have been reading about issues with that but I don’t believe that’s my issue since the internal temp in my trailer isn’t below 40°.

Any ideas on what could be the issue?

[LHaven]

It's not the gateway problem, because with that, not even the blower would activate.

My first guess would be that your ignition sparker is faulty or fouled, and only occasionally igniting. If the furnace doesn't ignite in some set time, it turns off to avoid spewing raw propane.

[wiredgeorge]

Have you tried lighting your stove to ensure your propane is flowing?

[Bporourke2]

Have you tried lighting your stove to ensure your propane is flowing?
Yes I have, everything else that uses propane works fine. My tanks are practically full as well.

[ChuckS]

Some suggestions...
Blower runs but are you hearing the DSI sparking when listening outside at the furnace exhaust?

After 3 failed attempts furnace will go into lockout mode...to clear turn thermostat completely off and back on to reset lockout

If you run the stove long enough it should have purged any air to furnace line

2 items that will prevent furnace light off are .... sail switch sticking and not making continuity or the furnace control module itself has failed.

If you have a multi meter skill set you can TS yourself to determine what’s at fault.

Access to what you need to get at will be thru basement of drivers side..have to remove rear cargo bay panel to get to furnace.

[ChuckS]

Any further luck with your furnace issue

[Bporourke2]

Yes, it was in fact the sail switch. Had it swapped out today under warranty.

Thanks for all the help!

[djac13]

@Bporourke2, isn't the doorless unit annoying?

did you have to remove the entire unit to open the unit up?

did you cap the gas propane or plug it someway to continue using the gas?