Hey I'm having almost the exact situation in my 97 Tioga Class C, except mine just cycles twice then gives up. It lights, stays lit for about a minute or less, then goes out, it lights again for a minute then goes out and stops cycling. If I go to the outside access door and flip the switch out there it seems to reset and does the same two cycles again with the same results. During all this, the blower in the furnace is running fine but just blowing cold air since the the flame keeps going out. In reading some of the comments in this thread, are you guys saying I can remove the furnace and clean it?