Here are tips for inspecting belts:
Look for cracks, fraying, or splits on the top cover.
Look for signs of glazing on the belt’s sides. Glazed or slick belts can slip, overheat or crack.
Twist a serpentine belt to look for separating layers, cracks, or missing chunks of the grooves on the underside.
Replacement belts should be identical in length, width, and number of grooves to the factory belt. Serpentine belts are usually kept tight with an automatic tensioner. Signs of a belt-tension problem include a high-pitched whine or chirping sound and vibration noises. Without proper tension, belts will slip and generate heat or fail to turn the accessories.
If in doubt, check with a qualified technician about any cooling problems, and always consult your owner’s manual for routine maintenance procedures.