Wise man at the shop, the dryer/accumulator did need to be replaced, it gets garbaged up over the years and can get prone to leaks. Next time you go in for a charge...

Now, be brave. If the clutch on the compressor has too large a gap, it will not engage when hot. So start up the engine or when you come home and the AC no longer "works", look at the clutch and see if it is spinning.
If not, then using a short broom stick, carefully tap the clutch towards the compressor. WARNING, the clutch will start spinning and you don't want to touch the belts or other moving parts!!! If the clutch engages, then the gap is too large.
The permanent fix is to move a shim or two from behind the clutch to infront of the clutch, depending on the gap. There is another temporary fix:

http://volvospeed.com/vs_forum/index.php?showtopic=80181


Klaus
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I still miss my 164 and my 854T. Just driving a V70R :)