RV Repair: Furnace 1979 Suburban NT24, intake tubes, happy camping

Question
My furnace turns on and warms up. When the thermostat setting is reached it turns off. The problem is when the thermostat calls for heat again,the fan starts and then backfires like a shotgun. Suggestions for a remedy? Thanks!

Answer
Gene,
    My best guess is that you have had a hornet, wasp or other critter building a nice new home for themselves in your burn chamber.  You should be able to shine a light in the exhaust and intake tubes on the outside of your RV and look inside to see if you can see any nests or other obstructions.  If thats not it then it may be incorrect gas pressure at the furnace.  The only way to check that is with a manometer.  I hope this helps, good luck and happy camping.

Darren