Is it all fan speeds or just one in particular? Almost sounds like wiring plug going to fan switch may be loose. I would also check fuse for fan to make sure it is seated correctly. Pull it and look to make Shute it doesn't show signs of overheating. Discoloration of fuse or discoloration on wiring plug or switch.
---------- Post added 01-22-2014 at 05:15 AM ----------
All fan speeds not working, its been over a week now since it has even worked, checked connections behind knob and all are fine, and checked fuse, I have no owners manual, so what i found online was the #3 40 fuse for heater and that was fine.
There is usually a resistor block that is mounted in the ductwork. These resistors are how you get the different speeds. They are actually exposed to the airflow in the ductwork to keep them from overheating. If the plug has come loose, you would loose fan speeds.