AC/ Heater Blower (fan)

Can anyone tell why the first two positions on the fan switch will not start the blower for the AC or Heater? Turn to the third, you can hear and feel air coming out of the vents. 2001 and 2003 Alero. Thanks Tony

Sounds like a bad blower motor resistor. It's a very common problem, usually caused by water leaking down into the blower motor from the cowling. They are not very expensive, and you can change it yourself. Search here for "blower motor resistor", you'll find instructions on the change.