Fan Problem

Hello,

I have a 1995 Nissan Maxima. The fan on my car runs at 4 levels - 1/2/3/4. After I started the car today morning the fan is not workin on 1/2/3, but is ONLY working on setting 4.

1. What might be the problem?
2. How much would it cost me to fix it?

Any help is much appreciated.

-Thanks !