2000 air condition stopped working??

My lady told me that the air conditioning stopped working. I Doubled checked it and yup it isnt working. I checked the fuses under the hood and swapped the fog light fuse with it and it still didnt work. I checked the pump and the center part of the pulley isnt turning when you turn it on and I noticed the rpm's didnt die a little when I turned it on like it would if it was working. What could be the problem?? How expensive would it be to take it in ,do you think they would find the prob right off??

Do your fans work when the a/c is on?

I'm not sure...I'll have to go see when she gets home,it hasnt over heated.