I made my furnace work yesterday. I had to replace a fuse (really!) and the fan limit switch. The latter is an 8-inch probe that sticks into the plenum and acts as both the blower fan controller and a high-temperature safety override for the gas valve. Let there be heat! And it was hot.
This was just one of many things that the previous occupant neglected.
Now if only I could be sure my heat exchanger was intact… cough, cough. Wait, why am I feeling sleepy and lightheaded all of a sudden?
P.S. Oh yeah, I also replaced the battery in the carbon monoxide detector. :)