Originally Posted by BMWHoochie

I was replacing my power steering pump which is under the ac compressor so I didn't need to disconnect the lines as my AC system works just fine. Just needed to move it out of the way.

Correct, before you disconnect those lines the system must be evacuated or you will have high-pressure freon and compressor oil spraying everywhere.

After the system is evacuated you are free to remove the lines, install the new compressor, and then have the shop fill the system back up and you are good to go. Make sure you don't have the AC turned on until the shop fills the system back up. I think BMW charges around $150 to fill the system back up.