Guys, NEVER use belt dressing or lubricants on belts, -either serpentine or V-belts!!!

Belts work by friction between the belt surface and the pulley. The noise you get is from a belt that is slipping on the pulley. Lubricants reduce friction and just make it slip worse. Slipping belts overheat and polish the pulleys leaving a "glaze" behind. Lubricants and dressings deteriorate the belt surface. Belts can slip because they are old, get foreign substances (oil, water, AF, etc) on them, or there is a bad accessory that is putting too much stress on the belt. Once a belt starts slipping it is shot and the pulleys are ruined.

To fix a noisy belt you need to remove the belt and either replace or fix the pulleys! To fix the pulleys clean them with some brake cleaner and then scrub the pulley surfaces with a scotch brite pad to remove the glaze and scuff the polished surface. Inspect the pulleys for damage or rough running. Clean the pulleys again to remove the grit. Make sure all of the pulleys turn smooth and easy. Put on a BRAND NEW belt, not the one you took off even if it is new. Make sure the tensioner works properly.