Engine belts that deteriorate over time are positioned at the front of the engine and play a critical role in avoiding costly damage. The number of belts differs from one vehicle to another but usually drives alternator, power steering pump and air conditioning compressor. To check them, open the hood with the motor off and look for cracks, separation, fraying or glazing while noticing their vein; they should appear nice and even. The tension of a belt is determined through pressing it down in between two pulleys where it should drop about 1/4 inch. Setting up the tension requires loosening a lock bolt on an adjustment assembly as well as rotating a slide bolt then rechecking it before tightening both bolts again. In order to change one's old belt however, it has to be replaced by new one which must be marked after removing the former using adjusting method when marking belts and pulleys is done properly. While changing out an older AC compressor belt built 2008 or later on use a pry bar to relieve pressure. Replacing drive belts for earlier models built in 2007 or less comprise removal of belt cover; drive belt itself; tensioner bracket; tensioner bolt; put back everything together starting from reverse order.