AC Makes loud Noise?

Hey guys! Longtime no talk because I had no problem with my 2000 528i.
Now as we have severs hot weather in the East, when I am using AC, it sounds very loud and abnormaly noisy. My son has the same car but it does not make this much noise when his AC operates.
Some one said I may need coolent/oil in the compressor? I have never heard about this. Is it true? Any idea guys?

There is probably a good chance it is low on refrigerant. The refrigerant carries the lubricating oil through the system so if there is a refrigerant leak there will also be a resultant oil loss.....both of which will cause a noisy compressor. I suggest not using the ac and have a tech look at it (soon) before the compressor completely fails. As a reminder, the ac compressor will also run anytime "Defrost" is selected. A failed compressor can get expensive to repair as usually you have to replace the compressor, drier, and, most times, the condenser as they are near-impossible to thoroughly clean. Unless you have a very good understanding of refrigeration and possess the proper equipment (gauges, vacuum pump, etc) this is not normally a job for the DIY'er.