That really sucks. Mine started to catch, one morning. Smoke started poring out of the vents, had to put my head out the window, to see enough to drive it to an out of the way lot and let her go. I called the fire dept, which showed up in minutes.....And then the fire went out!!!!!! It stunk like burned leaves in the cab for weeks. I noticed the heater only worked on high speed. Like has been said, my blower speed resistors caught the leaves on fire....and then the fire wrecked the resistor. I changed the resistor and vacuumed out all the leaves I could reach through the resistor hole. Truck has been fine ever since and that was maybe 10 years ago, now. Moral of the story, you guys, is to take out your resistor and clean out the leaves BEFORE your truck burns to the waterline.
Bill