Furnace shuts off before reaching setpoint

[GeneAubrey]

Dfdm35131 dometic furnace shuts off before reaching setpoint. If I shut it off and restart it runs a while and shuts down again, repeat, repeat same results. Sometime it runs for 5 minutes, sometimes less. Thought it was sail switch but camping world said no, it was a short in the gas valve??? Don't really believe that. Another thread said black 15 amp resettable fuse cured his. Camping world left furnace parts loose and shut off so they can sell $78.68 part and install it. Think I'll try the fuse first

[chuckster57]

Also check the high limit switch.

[sourdough]

Anything blocking that outside vent? I put a seemingly non affecting bug screen over the exhaust on my Dometic/Atwood furnace and it began doing exactly what you describe because it blocked too much exhaust....unbelievably. Removed the screen, removed the problem.

[Customer1]

I would suspect as said above that it may be overheating or a bad high limit switch.

[GeneAubrey]

I failed to mention that I did that first, thanks

[ChuckS]

So I gather you have the RV back home and you’ve reinstalled whatever the repair place left disconnected?

If so then did you replace furnace fuse? If it’s an auto reset style it will usually be black in color and 20 amp...

If furnace is back together then simply replace fuse and see what happens.

Also..make and model of RV is most helpful ...

You stated it’s a Dometic/Atwood AFM35 series furnace...

Is your thermostat a digital one with remote temp sensors, old analog style, or In Command HVAC global connect?