Furnace problem

[gblackburn120]

Good afternoon everyone. I'm having a problem with my furnace. I have a Crossroads Rezerve 31sb, 2016. It has the Atwood furnace in it. It started on me last time out, but seems to be worse now. The furnace kicks on, fan/ blower runs, the combustion chamber lights and heats for about 10 seconds and shuts off. 20 seconds later it lights again and stays on for another 10 seconds again. This goes on until it gets to temperature. I believe it use to stay lit and heating for the entire duration until it brought the camper to temp. Both propane tanks are full, the blower continues blowing air the entire time. The thermostat is set to 75 degrees, doesn't matter if blower switch is set to on or auto. I'm sure someone in this forum family has ideas or thoughts. Thank you all in advance. I'm wondering if a blockage in intake or exhaust? The exhaust vent is siliconed to side of camper and not where I can cut it to remove to check inside. No access to internal furnace inside camper, other than removing wooden vents under refrigerator. It's self contained under there.

[RC3]

I had similar problem except no gas going through. I had to actually take furnace out to diagnose problem. Same location, behind vent under fridge. Had to remove vent to access furnace for removable. Initially thought it was sail switch inside furnace. That usually turns off furnace if no propane detected. Tested it and it was fine. It turned out to be the motherboard. I think your going to need to get access to furnace and pull it out just like I had to do. Good luck.

[Crazyt]

If these unit have a flame sensor like on residential furnaces the sensor is dirty if you cane locate it with the unit powered down and gas off clean the sensor with some sand paper or scotch bright pad.
If these units use a hot surface igniter do not touch it ( they are fragile )
The flame sensor is just a small steel rod in front of the burner tube thee igniter will be flat or coiled and dark gray in color.

There should be a access panel to get to the unit ether thru the return air vent or the under belly storage area



I have been in the HVAC industry for the 42 years.
Good Luck


Jeff T