My Wife's 98 Protege stalls at idle when the A/C is turned on. There seems to be an incredible drag on the engine. If I keep the RPM's at 2,500 without the A/C on and then switch it on, it drops to about 1,250. Then stalls if I come off the gas. Any ideas as to the problem? I think it has to do with the compressor, but I don't know how to tell.