[66joej]

[QUOTE=Mdm5487;371181
"Sometimes it runs 10 mins or so like all is good and shuts off. Other times, cold air and maybe 15-30 seconds runtime". [/QUOTE]

Check the sail switches. Should be a warranty item.

Just an FYI. We are in Bullhead City AZ for the winter. Had the 35,000 btu Atwood/Dometic furnace stop working. As it was still within the warranty period I called a local authorized Dometic dealer. Came out to fix it. Turns out it was the primary sail switch. According to the RV Techs who came out to do the repair this is a very common failure on this particular run of this model furnace. In fact they keep a stock of these switches as they get several calls for the same problem.
Bottom line if your furnace does not cycle past the purge stage and into ignition this is most likely the problem.
If you are out of the 2 year warranty and a bit handy it's about a half hour labour to fix. Switch is about $10 on Amazon.
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