If its not blowing at all, try the high fan mode. They have a resistor that is known to go bad and all you will get is air on high. If that doesn't work it may be your blower motor, or your blend door may have fallen down and stopped your motor from turning.

 

The "door" above the fan is the door that gives you either outside or inside air. I ripped mine out and sealed off the outside air screen.

 

I just had to replace my fan motor and now everything is working great.Does your fan stop or slows down on the high setting? mine did, sometimes I would have to tap on the blower motor housing to get it to run.

 

x2 goodluck...