RV Repair: Suburban SF-35 furnace, wasp nest, limit switch

Question
QUESTION: My '95 Bounder 28T has a Suburban SF-35 furnace that would heat just fine until sometime during a late night on-off cycle, it would just blow cold air. Occasionally I could turn the thermostat off and on and it would light again. Recently it stopped lighting altogether, but the fan still works. Any suggestions?

ANSWER: Sounds like the limit switch. Part is inexpensive but access is difficult. It is a 2hr job at most any repair place. Good Luck.

---------- FOLLOW-UP ----------

QUESTION: Shawn,

I replaced the limit switch with no effect. Whats the next step?

Thanks for your time and expertise,

Jim

Answer
Try replacing the sail switch. Its located next to the blower. I'm guessing at this point. You can check it with a test light. Set the furnace into the point that it fails. and see if both wires have power. If so the sail switch is OK. After that I would ck for wasp nest in the burner chamber. Let me know.