Furnace help needed

[214skier]

2020 377FL.

Issue:

Furnace nor the fan will come on when I adjust the thermostat. All other thermostat related systems work fine: AC, AC Heatpump, Fan.

Evidence:
Just a month ago we took the rig boon docking and the furnace worked fine over several days
Furnace has not been run since returning home
Yesterday I changed the propane out (did I vapor lock this?)
Hot water heater runs fine on propane
I ran the cook top for over 20 min on propane to ensure the line was cleared
I have 100% on both lithium batteries


Action yet to be taken:
1. I have not taken the Dometic cover off (it is still factory caulk).


Help--we are supposed to leave for a 10 day trip tonight.

[Daryles]

Simple test is to swap the black 15A self resetting fuse with a regular blue 15A fuse.
Next.
You are going to need to take the cover off the furnace and check the "RESET" switch.
Cyle it off then on. You can accomplish the same thing by pulling the fuse and putting it back in (reset) but in this case you want to verify the switch hasn't tripped.
While you have the cover off, look for water intrusion on the circuit board and under it. Mine was intermittent. I discovered water on and under the board and evidence of previous water intrusion. I thought I had a good seal and good Caulk around the panel.
If you have a multimeter download the furnace manual from the files section and follow the troubleshooting chart.

[raygreg]

I just had the same problem (No Fan) repaired after I replaced a board in the furnace and a board in the heat pump, that did nothing to remedy the problem.
The skilled repairman found a bad connection in the wiring behind the furnace. It was a wire that came from the AC control board to the furnace.
Only charged me for 2 hours labor @$180 per hour.

[214skier]

Thank you for the follow up:

I took the cover off and there is no sign of moisture.

I reset the system and it is still inactive.

I noted the red LED light on the motherboard is out--I am guessing the system does not have power.

I replaced the black fuse for a blue one--no improvement.

[Daryles]

You will need to troubleshoot the 12v furnace supply wiring.