WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Install 3/8 inch breaker bar on the drivebelt tensioner arm and turn the breaker bar clockwise enough to relieve the tension on the drivebelt.