Sounds like the compressor is not kicking in and since you don't know where the compressor is located, best to take it in. If the compressor needs to be replaced you will need to remove the refrigerant in the system, which will require special equipment that you probably don't have.
If you are located near Avoca in upper New York, you can take it to South Main Auto. Eric is probably one of the best mechanic out there. Unlike a BMW dealer, it's not going to cost you an arm and a leg just to get back cold air for the summer.
https://www.youtube.com/channel/UCtA...PBhzTHA/videos