PART 1
All right, there are a few folks out there who would like to relocate these controls to someplace other than the glove box, but the cable control has always been the roadblock. The fan knob is just electrical so it's straight forward to just cut the wires and splice in extensions to lengthen them. The vent selector is a simple 6 vacuum lines. They can be cut and rubber hose added with a dab of superglue to keep them tight. The middle knob is the real problem.
It's a cable operated device that is under tension and quite difficult to extend. That is the focus of this thread.
First thing I did was order a new cable to see how the whole thing worked. The part number is #10418042 and it is about 20 bucks from GM Parts Direct.
There is a small end that attaches to the knob and a big end that goes under the dash on the passenger side. Just drop the plastic foot panel under the dash and follow the cable. It is held on with one screw.
The sheath holds one long cable that has the ends crimped with lugs on the big end and a crimp in the center so the knob can grab it. The whole cable is under tension from the spring on the big end. The sheath is also divided in two to keep the 2 cables from rubbing against one another. I doubt that makes any difference and a single large hole should work just as well. How much rubbing do they actually see anyway?
Here is the back of the controls.
