Volvo: 850 Turbo Wagon A/C, independent mechanic, failure rate

Question
Why, oh why, can't anyone fix the a/c in my 94 850 turbo wagon?  We have had the entire system, including blower motors, replaced twice since 2001 (once by an independent mechanic, once by the dealer.)  Sometimes it blows cold air, sometimes it doesn't.  Sometimes the fan works when I start the car, sometimes it doesn't.  The a/c tends to work fine on moderately hot days but not on those pushing 90 or more degrees.  We have literally had this into the dealer for a/c specific issues almost 20 times in the past 5 years. (Of course, things tend to work fine when the car is sitting on the dealer's repair lot, and things go wrong when I'm out and about making frequent stops.)  Each time we take it in we pay lots of money to have the problem "fixed" only to have it occur again a few weeks later.  Do we just have a lemon?  I love my wagon, but I'm hot!!!

Answer
Kim,
The A/C compressors have a high failure rate. That is due to the the clutch gap being to great. Have your favorite shop look into this. What happens is that the A/C works great and then cuts off and usually will not come back on until you stop and restart. There is also a switch in the compressor that turns the compressor off if it gets to hot. You can have your shop bypass it by wiring around it. This has been an excepted practice for a few years now.