2001 Grand Prix AC control stuck

[SWRTSWRT]

I've seen countless threads about A/C issues, but I didnt see one on how to fix the control when it sticks. My girlfriend owns a 2001 Pontiac Grand Prix GT and her AC control knob that allows it to shift positions was on the blower towards your face. She went to switch it to defroster and the knob got stuck so she tried twisting it harder and the knob broke off. I tried turning the selector with a pair of needle nose pliers and I couldnt get the thing to shift. Anyone else experience this before? I'm trying to do this as a preventative measure. The next step would be trying to clamp the thing with some vise grips and I'm worried that it'd warp the metal selector arm and I wouldnt be able to get the knob back on. Any input would be appreciate. Thanks guys!

[richtazz]

that knob turns a vacuum operated switch that diverts engine vacuum to different diaphrams depending on the position desired. The vacuum switch may have come apart internally jamming it up. You can take the HVAC control head out and inspect it to see if this is your issue.

[SWRTSWRT]

Hmmmm. I see. Pain in the butt to get to?

And I appreciate the response. Is this a common problem?