It may be low voltage getting to the clutch. You can check it out with a VOM connected to the clutch and sitting on the pass seat. I found the volts dropped to less than 11 and the clutch could not pull in. I put a relay in the circuit. and all is well now. Here is what I did.

First you need to locate the wire to the AC clutch. Follow it back from the clutch and you will find a small square box, this is the thermal limiter. It is not needed and is a problem area. Take the wire from before the thermal device (the wiring harness side) and extend this with a few feet of wire and take the wire from the other side of the thermal device and extend the same way. These wires will hook up to a relay(Std Bosch or Hella foglight type relay). This can be mounted any where you decide to put it. The wire going TO the compressor (The wire from before the thermal device) is the trigger wire for the relay. You will need a power source for the load. I took it from the battery. Dedicated wire with a fuse. The other compressor wire is load. This will give you full battery voltage to the clutch. When I did this over 2 years ago my mechanic thought it was a good idea but how much time will you get? And is it really worth it? So far well over a two years of 50 miles a day.
I'm not the best at describing things in writing. Hope this helps.
Any other questions, please ask.
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Howard Berman 2002 V70 90K, 95 850 wagon 162K, 2000 S80T6 72K, 94 850 Sedan 140K, 68 1800S 80K(My Toy)