Thread: Heater issue

A few months ago it stopped moving between defrost, vent and floor and got stuck somewhere in the middle with air coming out all three. Yesterday it stopped coming out everywhere except a little out of the vents. Blower is working fine. I crawled around under the dash but didn't come across anything loose or disconnected.

Where do I start to diagnose this?

2001 Pontiac Grand Prix SE 3100 with dual climate control.

Update: Chased a vacuum line based on something else I read. Found one that comes down over the passenger side strut and behind the battery that was broken. Started following it with my hand and it just shattered.

Anyone have a vacuum diagram? I'm guessing this jumps into the wiring harness behind the battery and through the fire wall. It's broken far enough down I probably need to replace all the way through the harness. There's one that comes through the firerwall on the passenger side and then up to the side of the heater. Is it the same one?

Blend Door.

The search button is at the top of the page in the black. Search blend door and that should lead you to a fix for it.

Had same problem with my 97 gtp.. It cracked in the same spot. All I can tell you is that it runs from the blower area through the firewall and then goes behind the battery.

Can you take a quick picture of the area you found the leak? I may have the same issue and not sure which spot you found your leak at and want to check mine.