2003 pontiac montana minivan heater problem

My 2003 pontiac montana minivan will only blow warm air when accelerating. When we come to a stop at a light the air will go cold. Also we do not get any warm air until the temperature gauge has climbed quite a bit. Any ideas as to a fix?

I suspect a vacuum leak in the HVAC system. The airflow doors, or flaps, within the system are vacuum controlled. When you accelerate there is less engine vacuum and when idling or decelerating there is more. A leak in the system will allow the flaps to move when they shouldn’t, and the symptoms you describe are typical of a vacuum leak.

Sorry Mcp, but I respectfully disagree with the point you made referring to vacuum controlled doors.

I have the exact same system in my Olds Silhouette and a couple of months ago I was having problems with cold/warm air direction.

After testing my tech took the dash apart, sure enough, the ELECTRIC door motor was burned out.

The Montana is a sister to the Silhouette.

Thanks, Roadrunner. I’ll try to remember in the future. I know some vehicles use vacuum and some are electric, I just can’t keep track of which are which.

Don’t feel bad, I can’t remember all the info either.