You most likely have a vacume problem. There are small air lines (like the kind used on fish tanks) that open and close valves, vents and the compresser I think... You can pull your radio and check out your control knob, see if maybe its disconected, then start it and see if you hear a hissing sound from a leak. I do not think that any of this system other than the fan is controled by a fuse. If its a fan problem check the wireing, fuse or there is a resister that controls the different fan speeds which likes to go out.
Hope this helps. | 
