1991 Oldsmobile Cutlass water pump.

Noises problem
1991 Oldsmobile Cutlass 6 cyl Four Wheel Drive Automatic

I have a 91 cutlass and my cooling fan does not work. I got the fan tested and it fine, but I cant figure out why it doesnt come on like it should to stop the car from over heating. I have gotten different things checked or changed like the fuse, I got it checked then I got a new relay switch put on and it still didn't work. I got all my wiring checked to make sure there wasn't a shortage somewhere in there. Recently my serpentine belt broke, which im replacing tomorrow. What else can possibly stop my cooling fan from coming on? I also had my radiator checked for leaks and it was working fine.
Thanks for any insight you can provide.