just did some work on my girlfriends car. Turning it on for the first time in a few weeks. Turned on the AC and this loud noise was coming from the front passengers side of the engine. Not sure if anything relates but I just replaced the turbo’s water pump and flushed the coolant. I also replaced the radiator fan but that’s not where the noise is coming from. Any suggestion? My next guess is a soon to snap AC belt. If the car has one. I’m not proficient with these cars yet. Oh it’s a 2011 cooper s. Thanks!