2005 Chevrolet Malibu 3.5L
First remove the air cleaner assembly. Then remove the engine strut mount. Rotate the tensioner pulley clockwise to release the tension and remove the belt. Look over all the pulleys and make sure they are not damage and are free of any debris or fluids.
Route the serpentine belt according the diagram provided around all of the pulleys leaving the tensioner for last. While keeping tension on the belt rotate the tensioner pulley again to release the tension and slip the belt over it. Look over all pulleys and double check that the belt is aligned on every pulley correctly.