1995 s320
today I pulled into a parking space everything was fine , a couple hours later I went to start the car and heard a squealing noise under the hood.
facing the engine on the left side was a pump of some kind that was frozen so that the belt spun around it but the pulley didnt move, i'm trying to identify what its function, it has a black u shaped rubber hose coming out of the rear like a discarge or vent of some type, it's not the alt or a/c compressor or water pump which are all driven by the same serp. belt. I'm guessing that it's a vacuum pump of some type sets just to the side of and a bit lower than the air box for the air cleaner, or perhaps its a smog pump i really dont it seems to have a vacuum line coming from it but only one and it is small (1/4 in).does anyone know what the funtion of this pump is?