Well, the AC compressor started knocking on the S60, so I decided to do some exploratory surgery.  After removing the belt I noticed the clutch was very wobbly.  I naturally assumed the clutch was bad, unfortunately, that was not the case.  The clutch bearing was fine, the entire clutch assembly was wobbling on the shaft.  This damaged the shaft housing which is part of the compressor body, yes time for a new compressor.    The compressor was around $450 – $750 depending on the parts shop.  It was just too much, I found one in a junkyard in Florida for $100.  I had to also purchase a vacuum pump from Harbor Freight for $80.  The system also calls for 5.7 OZs of PAG 46 oil, and 24 OZs of R134a freon.  This is for the T5, I think the T6 has different specs.  I removed the old compressor and added the PAG oil to the new (used) compressor and installed the new compressor.  This was the hard part, the freaking belt.  This car has two drive belts the big one has a tensioner and the small, AC belt, has no tensioner.  So to install this AC belt you have to install the front two bolts in the compressor, leave them loose.  Then place the belt over the pulley, then tighten down the rear bolt to apply tension to the belt.  The problem, there is NO adjustment for the poor belt and I bet it has 400LBS of pressure on it!  I had to use a hydraulic jack to push the compressor into place.  I think this is why the clutch destroyed the compressor housing, the belt is just crazy tight.  I know it is going to destroy the new compressor, hopefully I will sell this thing before this happens. Maybe I could have purchased a belt that was .25 inch longer, not sure, but this was the OEM size.  After the hours-long fight with the belt, I hooked up the vacuum and vacuumed the system for about 5 hours.  The little 2.5 CFM vacuum from Harbor Freight worked well, and it was very quite.  After the vacuuming, I added two 12OZ cans of R134a; it took the system several minuted to consume both cans.  I also changed both drive belts since the were off and due to be changed.  The compressor works very well, you can just about make it snow in the car now.  This was my first AC compressor change.  I feel pretty confident now, I have always wondered how hard it would be to change a compressor.  I may be converting the ’66 Volvo from R12 to R134a in the near future.

A video of the vacuum running:   https://www.youtube.com/watch?v=6bsPwijc6zY

Products used:

• 5.7 OZs PAG 46 compressor oil
• 24 OZs R134a Freon
• Two new belts
• Used compressor from Florida