Use a tube like vac wand to ear to try and locate precisely. Could be belt is bad and slipping (grooves to worn) or your air pulley bearing or idler pulley beariing. Also check that bekt has good tension as tensioners can get stuck or loose tension.
May, 26, 2012 AT 8:31 PM
I put the vacuum tube to each pulley and it sounded the loudest and most high pitched at the pulley between the waterpump and the AC. Does that mean much to you?