Dan, I'm no expert on these furnaces but I do have several hundred dollars invested in lessons.
We drove 1,500 miles a year ago January to pick up our new (to us) 15' Trillium
. On the way home we decided to sleep in the trailer. I lit the furnace
and slept the night away comfortably at 26 degrees F. That was the last night the furnace ran all night. I took it in to the RV dealer and he suggested a new thermo coupler. So in one went! Still it would not run all night. Back goes the trailer and the gas expert cleaned all of the lines and checked everything. He even let it run for 3 days to make sure it worked. Great! Now we are fixed.
Wrong! We took the unit to Arizona mid winter and the same old problem. It would not stay lit all night. ^&%$($#
Back to the shop when we got home and by now I'm not too happy. Finally, after checking everything again the gas expert asked me how I kept the little flap that covers the lighting
hole when I ran the furnace. I said, "Open of course. I want to lean out of bed and see if the pilot is lit."
Bingo! That was the problem. The sensor just inside the metal wall of the furnace reads whether the pilot is lit. If we got the slightest breeze from the intake the flame bent outside the wall thru the hole and the sensor shut the gas flow off because it sensed no flame. That can happen if you are badly out of level too. We now keep the flap closed after lighting
and we remain toasty. :red
Good luck with yours.