Changing the serpentine belt in a vehicle involves rotating the tension pulley to give the belt slack, taking the old belt off, and installing the new belt. Carefully follow the belt's correct routing around its necessary components, such as the idler pulley and alternator.
Before beginning this project, have a new belt ready, and make sure it is identical to the old belt. Pay close attention to the routing of the belt. A diagram for the routing often appears on a sticker under the hood or in the owner's manual. If not, draw a sketch of the route for reference later.
Most belts are easy to change, and only require an open-ended wrench or serpentine belt tool to rotate the tension pulley and allow the belt to slip off. Fit the wrench over the bolt in the center of the tension pulley, and pull upward. The pulley should rotate up, allowing the belt to slack for easy removal.
Inspect the old belt for any cracking or damage to the inner grooves of the belt. Hold both belts up against each other to confirm they are of the same exact length. Rotate the tension pulley again with the wrench, and slip the new belt on, making sure to reference the routing diagram. The grooved side of the belt should fit in with the grooved pulleys, and the smooth side should come into contact with the smooth pulleys. Gently push the belt until it fits in place, and drop the tension pulley back into its resting place.
With the hood still up, start the car, and listen for any squeaks or squeals coming from the belt or pulleys; check the installation if you hear anything out of the ordinary.