possible issue with belt or timing chain. vehicle run in idle, all components at rest. turn air on, added stress to belt. possible worn out pully kit on one of components powered by belt. bring to a shop and have them inspected. get diagnostic run to see any other issues you should be aware of.
RepairPal Certified shops can diagnose and repair your 2002 GMC Savana 3500. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
