Blower motor works intermittenly usually when I hit a bump.

I have a 1997 Oldsmobile Regency with a V6 3.8L w/ ac. I was going to replace my blower motor because it stopped working, but it comes on from time to time especially when I hit a bump. It could be a loose connection was my first thought but I don't know where to start. I was told by the auto parts clerk that it may be a resistor, but I don't know where it may be located. Any information on this topic will be greatly appreciated.