I had the same problem in my 1995 850 at 110k miles. The fix was to remove the shims. The car is now 176k miles old and the fix has lasted so far.
AC is on 100% of the time the car is used.

I took the car to an AC shop, and work was done from under the car. It took a little bit over one hour. The splash guard was removed, the right front wheel was removed and a couple of screws holding the compressor to the subframe were removed. The compressor drops down enough to reach the screw on the center of the clutch assembly. The hoses to the compressor were not removed, so there was no need to recharge the system. There were three shims. Two very thin and a thicker one. Just the two thinner ones were removed.

Hope this helps.

Icelandic

While what you are asking is feasible it isn't too practical from a business stand point. What kind of guarantee are you looking for on this work? You have diagnosed it and you would like to have a shop adjust your worn out clutch. While it will probably work just fine if it does not or if it quits working in a relatively short time you will find yourself having spent a decent amount of money for a repair that did not hold up. This is why shops do not like using customer's parts or basically holding hands with the customer on repairs, it just makes bad business sense. If you are determined that this is the avenue you want to take I suggest you contact a Volvo specialty shop or an A/C specialty shop and see what kind of answers you get.

Mark