Re: Problems with vent knob
Sounds like a vacuum problem. The only cable on the HVAC system controls the cold-hot temp. Pull the control off and you'll see a vacuum harness that plugs into the back of the controls. In the controls there is a sliding disc that directs vacuum from 1 of the hoses to open the different doors inside the dash for defrost, vent, A/C, off, ect. Make sure all the hoses are hooked to the controls and that one of them supplies engine vacuum to it. Good luck with it.
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