How do I relieve the tension off the alternator belt
2 Answers
On any serpentine belt setup there will be a "tensioner" pulley. The tensioner pulley usually accepts a socket and turning that causes it to slacken. Just don't confuse the tensioner pulley for the "idler" pulley.
If there is no serpentine belt but a single belt for each belt driven accessory, then you will have to loosen that accessory via the mounting bolts, remove or place the belt, then pry it back into place to put tension on the belt and tighten down those bolts.