RV Repair: Suburan Furnace NT345, wasp nests, combustion chamber

Question
We have a 1984 Itasca Motor Home, we replaced the thermostat, now it will light the burner for a couple of seconds then goes out.

Answer
SHELLY
YOU  WANT TO LOOK INTO THE EXHAUST/INTAKE OF THAT FURNACE TO SEE IF YOU CAN SEE WASP NESTS. IT SOUNDS LIKE THEY ARE BLOCKING THE FRESH AIR INTAKE. THAT WILL CAUSE THE FURN TO RUN OUT OF FRESH AIR IN THE COMBUSTION CHAMBER, PUTTING OUT THE FLAME.

THOM