Atwood furnace issue

[Janesy]

Hey All, first post newbie here. I've search all over before posting this. I have found a couple thread with the same problem, but never a solution or follow up.

We bought a pre-owned 2015 jayco 19xud last month. Everything worked in the dealer lot
This past weekend the furnace (Atwood 7920-11) would randomly stop working. After a while, when the tstat turns over the unit just buzzes.

The red LED if flashing low air. (1 flash 3 second pause). The buzzing is coming from the ignitor coil. If you tap it, the buzzing stops. But it does not ignite until you demand it from the tstat.

All pipes are clean, doesn't look like it's ever been used.

It will run for hours then stop at random, tonight it ran for 1.5 hours before it did it . I cannot replicate it aside from turning it on and leaving it for the night. When it does this, you simply turn the tstat down, then back on again and the blower fires, and then the burner fires and it's good to go. For how long you don't get to know .

I haven't been able to replicate the issue, so when it happens, I don't know if the blower is coming on or not. Or how long it runs before the unit shuts down. As obviously it isn't fire the ignitor.

Every single time if hit the tstat, it's worked fine. It just won't stay working fine.

[Janesy]

Forgot to add...
Tried on two different full propane tanks, shore power, fuses are all good.
Be much easier to diagnose if it would constantly give up on me

[Colorado]

If it’s hasn’t been used in a long time the igniter may have corrosion on it. I had a similar experience, I thought the furnace was dying. However, I had to replace the motor on mine. Then saw hose that provided air to the ignition chamber was dry rotted. I replaced it with an automotive hose. I also opened the ignition chamber and sure enough FULL of corrosion, cleaned everything with steel wool. Fires up almost immediately and heats much better too.
My suggestion is to pull the unit, clean everything then hook it up on a table outside. Then light it and let it run for an hour or so...

[Janesy]

So I've just sat and watched this unit. I'm not usually one to shotgun parts at something.

But it would normally work as such,
1)tstat signal
2)blower
3) ignitor
4) burn.

What just happened twice randomly, was it almost like it tried to do it all at the same time.
The tstat clicked on, then immediately the ignitor tried to fire and seized and started buzzing. The blower motor which would normally run for 15 seconds prior to the ignitor, does not even fire up. Then it get the no airflow LED flash. Which makes sense if the fan never get the signal to turn on
This all happened instantaneously.
Reset the tstat and it works fine.

I'm thinking the control board is not working properly.