Belts that are too tight can wear out the bearings in accessory components, such as AC compressor, water pump, and power-steering pump. Belts that are too loose will wear out faster and may fail prematurely. Check for tension by pressing in the center of the belt's longest exposed run while holding a ruler next to it. If you can depress the belt 1/ 2 to 1 inch (13 to 25 mm), but not more or less, the tension is good, if it’s determined an adjustment is needed your auto repair service shop do it. Also check for belt damage, such as glazing (often due to oil leakage), fraying, and cracks. If you spot damage, have the belt checked by a pro and replaced if necessary.