Just wanted to throw my name into the hat with others who have had to replace their ignition boards. My furnace is a Dometic dfsad12131 and came with my late 2019 19'. .
The Problem: Basically the issue was that the furnace would fire for the first cycle as the temp came up (or almost all the way there), then just bug out and not come on again.
Then: If I...left the thermostat on it would try to fire again some period later, maybe like 15-30 min, but would not ignite and shut down.
If I I...turned the thermostat off and then left it off for maybe 15-30 min, it would fire up again as described in the The Problem above.
If I...turned the thermostat off and then immediately turned it back on, it would not fire.
The Solution: I tried to clean the sail switch first, but did not help. I contacted Dometic warranty and they wanted me to go to a service center. I really didn't want to do that, since I use the trailer for my remote Covid office while my toddler uses the entire house (it's Ok, he is really cute), so I just decided to forget the warranty and bought a Dinosaur ignition board (Fan 50 Plus Pins). I read somewhere that they are high quality than a Dometic OEM board, plus I really like their retro website!:
https://www.dinosaurelectronics.com/index.htm
Fired up perfectly and working as expected now. Will report back if I encounter any further issues. I will probably bring along Mr. Heater as backup in shoulder season.
Dometic Furnace Issues Solved...Hopefully
Linear Mode
