2000 Temperature Control

2000 Grand Prix Manual Control

My daughter just bought the car yesterday and we noticed that the knob for the Manual temp control dosen't change the air flow. It just stays in defrost. Is this controlled by vacuum or is it an electrical change? The dial itself must be working because the A/C light comes on when selecting that mode, just only out of the defrost vents.

If it is in fact vacuum operated, what is the source of the vacuum?

Thanks in advance

I think its vacuum, and if I remember right, the vacuum source is the line near the battery. Check to see that it isnt cracked or broken off as its easy to do when you replace the batt.

Since the engine compartment was "detailed" by the dealer, I think that they have knocked something loose.

Checked the vacuum line that comes from the intake and loops near the battery. It is good and holds a vacuum. I am thinking that it is a problem with the control head itself. Any other ideas?

about all you can do is to remove the control unit and check for vacuum.

about all you can do is to remove the control unit and check for vacuum.

That's what I thought. It just looks like a PITA to remove the bezel to get to it.

its actually not so bad. Remove the two screws in the panel by the drivers knees, then just start pulling gently to unsnap the dash. Might have to angle the wheel down, and not forget to unplug the fog light switch.

Got it. Removed the control unit and there was no source of vacuum. The line was crushed. Remove the crushed section and spliced the lines with model airplane fuel line. Now it works fine.

Thanks for the help.

Great, glad to hear you figured it out, what caused the line to get crushed?

I have no idea or how long that it was this way.