Volvo Repair: Intermitent AC problems on Volvo S70, coolant level, volvo s70

Question
My Volvo S70 has developed an intermitent problem with the AC where it will start blowing warm air. It may do this a couple of times in a day, then may go 3 weeks without any problems. My local dealer checked the coolant level and found it was a little low, so they recharged it with dye. After about 2 weeks it did it again. The dealer checked the coolant level again and it was fine and there were no signs of leakage. They could not get it to repeat the problem. They replace a pressure switch which they said may be the problem based on a technical report they had. On the way home from the dealer, the AC quit working again. So far I have spent over $250 and I still have the same problem. Any advice?

Answer
Hello,
the problem is clear, it is ac pump (compressor). As a hint, I will advice you, when the problem repeats hit onto the compressor by a long strong stick, you will see that the system will start to work again, that means the problem is compressor. It should be replaced with new one.
Regards...