1998 Chevy Cavalier A/C suddenly stopped working

The a/c in the car was running completely fine until one day I tried to turn it on, and all it blew was warm/hot air. No cool air at all. I do remember hearing a banging sound of some kind under the hood a day or two before the a/c no longer worked. Don't know if this had anything to do with it. I have turned the a/c and looked under the hood to see what I could see and I do notice the fan in front of the radiator does not run at all.