In my old Dometic 2652, we had it connected via 120, left for a trip and when we got to the destination it was running on gas.
over the trip it go warmer and warmer and by the time we came home, it was in the high 40's to low 50's. Dangerous.
When I got home, I posted here and someone suggested I check the flue baffle. When I pulled it out the bottom edge was rusted away from the heat and the moisture in the air at night. I cleaned out the burner tube and replaced the baffle and it worked like a champ until the day I sold it, 4 years later.
If you're relatively sure you don't have a leak in the system, check the baffle, clean the tube thoroughly and try it again. I couldn't believe it was something that simple.