I believe that's a vacuum hose,not a wire.Look under the dash to the right of the steering column.It looks like the hose that goes to the vacuum motor which controls the defrost/panel vent.If this hose is disconnected,air will blow out of the defrost panel only.If you look at the diagram below on the left side where the yellow hose is displayed,you can see that no vacuum being present at that vacuum motor will move the door to the down position (making the air blow out of the defrost panel only) Vacuum being present at that vacuum motor will move the door to the up position (making the air blow out of the instrument panel vent registers instead) Rotating the knob to different positions directs vacuum to the various vacuum motors that control the various doors.
91 LX 342ci (10.5:1)
TFS 190cc (stage ll)
GT40 (tubular) intake
Weld ProStar XP's
Last edited by wbrockstar; 07-01-2019 at 09:42 AM.