Volvo: Volvo a/c, clutch assembly, compressor clutch

Question
The A/C on my s70 is inconsitent. When I first turn the car on it blows very cold but if i idle for a spell, say at a stop-light or drive-through, I will get this humid smell and the air will stop being cold (it continues to blow, only now it's not cold). If I restart the car, or the turn the a/c off and then back on, it will blow cold again.

We've evacuated the system and added dye; we've been running for a couple of months since, and still have exactly the same problem - no leaks. Do you suppose it could be the clutch?

Answer
Tom,
Sounds like the compressor is turning off after a short while on. Most times that is too great a gap on the A/C clutch. You need to verify if the compressor stops when this happens. I always replace the compressor/clutch assembly when this happens.