listen up everyone, I have had over half a dozen bimmers this summer in my shop for the same problem. 4 out of 6 cars had a bad high speed fan. what happens is that this fan kicks in when the refrigerant preasure rises up and the refrigerant gets hotter. the A/C high speed fan cools down the refrigerant in the condenser. if the fan was getting power but the temp or the preasure did not drop, the A/C compressor shuts off to avoid any damage to the system until temp and preasure are back to normal. have the high speed fan inspected by a mechanic or an auto-electrician (like myself......)