Your air conditioner runs fine for a little while then all of a sudden it blows warm air. The clutch actually dissengages and you have to turn off the a/c, wait a while then turn it back on and it will again work for a while. Mine would turn off whenever I accelerated hard and then would not come back on.
How to determine if the clutch gap is the culprit:
Next time the compressor clicks off (starts blowing warm air): leave the a/c on and take a wooden broomstick and push the clutch in with it. If the clutch engages with the push of the broomstick, you know thats the problem.
If the compressor is clicking on and off constantly every couple seconds, then thats a different problem, probably low freon.
Requires taking the clutch apart and putting some shims in somewhere.. I don't even know.
Take 3 plastic bread bag clips and insert them on the outside of the clutch to push the clutch closer to where its supposed to be so it can engage automatically.
You'll need to cut the clips the way they look in the picture so they fit (it will all make sense when you try sliding them in place). I used a flat head screwdriver to spread the clutch apart while I slid the clip in. I also put crazy glue on the clips just to be certain they are not going to fly out with the centrifugal force. Make sure you work quickly once the glue is on because it will soften the clip. Once they are all in just break off the end of the clips. The bread clips were just the right size for my compressor but yours might be different. My brother's S60 is having the same problem but the clutch is different. The gap is smaller and a bit harder to get to, I'll probably cut up some copper sheet metal or maybe some old razors and slide them in.
It took me about 15 minutes when I did it about a year ago and it's still working.
Attached is the photo.
Good luck and let me know if it works for you too.