The more I think about this, the more I'm led to believe that degradation of the oil has occurred, which is usually caused by moisture getting into the system via a leak, as has been said. If so, it might have happened unbeknownst to you before you owned the car. If the oil is contaminated and its lubricity compromised, then the compressor internals will also be affected, and eventually the compressor will fail. You might be on the cusp of the latter given the brown gunk you found in the R/D and the screeching that you're now hearing.kapilamuni wrote: ↑Wed Dec 15, 2021 11:24 pm I cut open the RD and it's holes are all blocked with some light brown colour dust like wet thing. Got few pictures but can't get them to shrink to post here.
A bad clutch bearing could cause the noise, too. One way to eliminate the bearing from consideration is to remove the clutch from the compressor (it's not necessary to recover the refrigerant to do this) and rotate the bearing by hand. If it feels rough and wobbly and sounds like an old-time metal roller skate, it needs replacement. If it turns smoothly without any play, it's probably fine.
If the oil has been contaminated with moisture, which will also cause corrosives to form, affecting the system components from the inside, then you're looking at replacing the compressor, condenser, and R/D (again), and thoroughly flushing and blowing-out the rest of the components using an approved solvent. You might or might not want to go that far to restore the system.
I use an app to compress photos for online posting called Compress Photo Puma that you'll find in the Google Play Store, which I presume is accessible worldwide. YMMV if you have an iPhone, but I've found that the app works great on Android.