When I bought my 2001 Land Rover Disco 2 it was already making a strange “whirring” noise. That’s the only way I can explain it. When I turned the ac or heat on the would make an additional noise but not the same noise. One day my ac pulley locked up and the friction melted through my serpentine belt. I’m not sure if I need to replace the whole compressor or just the pulley and bearing or maybe just the bearing. I’m going to take it apart soon but wondered if anyone might know the issue from what I’ve described.

 

I'd look for a good used replacement compressor from one of the guys here on the forum....