Furnace - No Heat

[Steady_Rest]

I have the same furnace and have replaced the temp limit switch three times over the past 22 years. In fact this has been the only problem the furnace has ever had. The temp limiter is a bi-metal switch that when bad becomes stuck in the open position, it is a normally closed switch. If the furnace gets too hot the bi-metal strip bends away from its contact due to expansion, creating an open circuit.
I have replaced these switches a couple times in my home clothes dryer when there has been a no heat condition.
Good job diagnosing your furnace. You have saved money and gained knowledge about how the furnace works.

[Hangfive]

I had the same problem in our T REX. Run but no heat. Pulled the furnace, found wasps filled intake fan with nest, and a dead bat came out of exhaust side. Lots of rust. Still no start. so installed a new furnace, and the screens.
It worked Great at home. on trip, no heat. Pulled the plug, cleaned the pins and spread them a little to encourage contact and has ran great since. Sorry I hadn't seen your thread sooner, as I fixed this in July.
I'm not sorry I changed out the furnace as it was in bad condition.

[bobioknight]

Neither of my furnaces are working and it is pretty cold out our way. Actually they are hit and miss, sometimes they work, then they don't. The local RV repair shop whats $300 to just to diagnose the issues. I will be surely going to be cleaning all connections, checking the sail switch (probably sticky) and blowing out any debris in there tomorrow FOR SURE. Thanks for the heads up.