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2020 Montana- Legacy - Dometic Furnace
Furnace with In-Command shuts off in cold weather. Originally shut off with temps below 35 degrees and once temp reached 40 degrees the furnace would start working again. If attempting to start the furnace the blower fan starts, after approx 10 seconds the furnace starts but quits after approx. 10 seconds. The blower fan continues to run and after approx. 15 seconds the furnace will relight but will quit again after approx. 10 seconds. This sequence will repeat itself. The blower fan never shuts off till after 15 min of this sequence. Fuel tnks are full. The fact that the furnace does works all day in temps above 40 degrees and regulator already replaced should rule out any propane issues
The sail switch is clean and has 12 volts from the circuit board to and from the switch.
The voltage from the circuit board to the thermistor is 3 volts. I have been advised the correct voltage is 12 volts.
The dealer after the 1st occurrence replaced the regulator but did not document any diagnosis procedure performed so one can not determine if any proper diagnosis was performed or merely shot gunning the repair process.
I went to the Badlands in 8" of snow and found out I would be vacationing in sub-freezing temps w/o a furnace when i turned on the furnace.

Now with temps in the 70's the dealer is unable to duplicate and wants me to pick up the unit. Montana is saying unable to duplicate - no repairs - wait till i have the unit out again in sub-freezing temps and then take it back to the dealer.

QUESTION - ANY IDEA WHAT PART I MIGHT NEED TO HAVE ON HAND TO REPAIR SAID CONCERN?