Is it just the fan? Can you turn the blade by hand? If not, the fan motor froze on you.
It's a bitch to find anyone that will sell you the parts, but Granger carries the fan motors if you want to replace it yourself. I had that happen about 7 yrs ago here.
Honest AC people are HARD to come by. Be careful that when they do a "tune up and freon install" that they don't screw with it and try to charge you for unnecessary repairs.
RJ