a/c Compressor
 

I was told that my a/c compressor was u/s and that I need a new one I was also told that I need a new drier insert because mine had been contaminated by burnt oil from the bad compressor, I ordered a new compressor and a new drier unit and had a local a/c guy come and install the compressor and drier unit as I was awayon business and my wife needed the truck, ut when the guy arrived he installed the new compressor and the drier but when he checked the old compressor there was no sign of burning and it was spinning free but the old drier was definately contaminated with burnt oil as you could see and smell it so if my old compressor was OK where did the burned oll come from and what would have caused my a/c to stop working in the first place my aux. fan is OK and the FSR was replaced so I am now baffled can somebody help me here please.