Symptoms - HVAC Systems - Manual: Intermittent
WARNING: This page is about a different car, the 2003 Pontiac Montana, 2003 Oldsmobile Silhouette, and 2003 Chevrolet Venture. However, it is still accessible from the selected car via links, so may be relevant.
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to INTERMITTENT OR POOR CONNECTIONS in Wiring Systems.