Could be the blower resistor, not sure what kind of car you have but check out this video descibes your problem to a T, i am sure the replacement is different on different types of vehicles.
http://www.youtube.com/watch?v=33fqw0k_qkM
ginwoman, did you get it fixed, if so just curious what was the fix?
Could be the blower resistor, not sure what kind of car you have but check out this video descibes your problem to a T, i am sure the replacement is different on different types of vehicles.
http://www.youtube.com/watch?v=33fqw0k_qkM