BMW SERPENTINE BELT

Is The Serpentine Belt Which Runs Around Alternator Also The Same Which Goes Around Ac.I Know It Is Very Long. What If A Mechanic Puts...

Belt Broke Bought New One, Doesn't Seem Long Enough? Do Know If To Continue With This One Or Take It Back?

Replacing Alternator And Have Had A Hard Time With This. It Would Be The Best Christmas Present If You Could Please Give Me The Belt Diagram...