2001 CLK320 107000 miles

When the air is turned on, it blows cold air for a few minutes, then the compressor shuts off and it blows ambient air.

I took it to my technician who suspected the system was low on Freon. He evacuated the system and re-charged it. The symptoms didn't change at all. He checked for error codes in the computer - there were none. He said to go back in a week, and if no errors show up, there is 90% likelihood that the compressor clutch is defective.

1. The clutch works fine when it gets juice. Could it still cause this problem?

2. Could the problem be caused by the pressure switch (on the receiver drier) that is not sensing the pressure in the system and is shutting off the compressor?

3. There is second sensor on the receiver drier. What does it do?


Thanks