Welcome to United Bimmer.
The AC system is very complex, and not something i recommend for DIY. The refrigerant, R134A is oxygen dispersing. Meaning it forces air out of the way. If your in a confined area and it leaks, or their is a blow out, you face the risk of serious injury or death. The system is under pressure and needs to maintain the vacuum pressure inside. It is recommened you seek a proffessional for this.