Here are a few things to check.
1. Turn on AC system and ensure that the compressor clutch and electric fan are spinning.
2. System operating lowside pressure should be around 30-32 psi. If the pressure is low, have the system professionally drained. BMW system must be evacuated, new compressor oil added and freon added to a specific weight.
3. If the compressor constantly cuts on and off, I would check for high system pressure, a bad sensor, or bad expansion valve. The AC tech will have the manifold guages to check the high and low side pressures.
Once you have the system functioning properly, a good practice is to run the AC system 5-10 minutes per month. This allows the system to cycle the freon and lubricate the seals.
Big Boyz with Bad Toyz.
Last edited by BigBoy740il; 02-17-2013 at 08:15 AM.