Blower motor only works on High

I dont know where it is in your car, maybe behind the glovebox, or somewhere by the blower motor, mine went out in my 90 subaru legacy and it would only work on high, no lower speeds, I went to a junk yard and paid $2.50 for a used one and after I installed it my fan worked on all speeds, thats my guess, these things go out all the time on lots of different cars, so this would be the first thing I would check, I went to a junkyard because mine was about $55.00 for a new one.
Hope this helps