Where to tighten a fan belt from on a vauxhall vectra?

To tighten the fan belt on a Vauxhall Vectra, locate the alternator, which typically has an adjustable mounting bracket. Loosen the securing bolts on the alternator to allow for movement. Then, adjust the position of the alternator to increase tension on the belt before re-tightening the mounting bolts. Check the belt tension by pressing down on it; it should have a slight give but not be overly loose.