Fresh Air/Heat Controls on Dash

[Superman]

Three sliding knobs on the dash, which control fresh air volume and direction, and heat direction (floor or defrost). Mine are sluggish - hard to slide. Particularly the lowest one with the red knob. The car is a '78. Fresh air box/blower is '78. The dash controls are from an 83, which is a little different, but the red knob works the same. I have the original ('78) dash controls and I have a spare set of cables and sleeves. Here is my question:

Does the routing of the cables and sleeves make a difference? I know the cables can get gummed up if someone has lubed them, and this may be the problem. But can the routing of the cables also cause poor operation of the controls? The cables are all routed through the same opening, into the trunk, on the driver's side. Is it possible that one of the cables should have a wider arc? Or, alternatively, is this problem surely caused by lube that has gummed up the cables and sleeves?

[86 911 Targa]

I would remove the cable cover located in the trunk.

Then, work the cables & check for binding.

Some one else might chime in for proper lubrication.

Gerry

[Superman]

I did that. None of them move as smoothly as I would like. The worst offender, the red knob on the dash, controls the rear (hard to access) of the smaller black plastic boxes in the rear corners of the trunk. Those controls, worked manually from inside the trunk, are VERY hard to work. Again, my question is whether the curve of the control cable coming from the dash, might be the problem or, alternatively, whether the curve angle is likely not the problem. In that case, I would guess, the problem is with the friction between the cable and the cable sleeve.

I hope Dr. Walker sees this. BTW, FWIW, I have learned to listen VERY carefully to John Walker's advice.

[gazzerr]

I have been through this. It's not the curve. Here's the thread:

https://forums.pelicanparts.com/porsche-911-technical-forum/896235-issue-fresh-air-controls.html

If the ends of the cables are not properly fastened with the bowden clips it will also bind.

[spuggy]

Originally Posted by Superman

Does the routing of the cables and sleeves make a difference? I know the cables can get gummed up if someone has lubed them
...
Is it possible that one of the cables should have a wider arc? Or, alternatively, is this problem surely caused by lube that has gummed up the cables and sleeves?

I think lube is pretty unlikely to gum up piano wire, unless you're using trailer grease or something crazy. I lubed mine with spray silicon when the ends were free regardless - didn't seem to make much/any difference. That was 10 years ago, haven't touched them since and they still move freely, sooo....

A bent cable or incorrect routing could be the issue. If you're lucky. Because that's relatively easy to address. Gerry's suggestion to remove the cable end from the airboxes and check for free movement is exactly what I did.

If the stiffness is in the cable or the controls, you're laughing - but once the cables are disconnected, should be pretty obvious what needs to be done.

It's also a possibility that the distribution boxes have broken or fallen apart inside and you need to remove/fix/reinstall. Mine were jamming up internally. In good condition, the flappers will just bang open/closed under their own weight as you turn them over out of the car...

Pray it's the routing. Or the cable. Or the controls...

Replacing the electrical portion of the ignition switch or the hood shocks is a breeze, by comparison. You've got to work to get the distribution boxes out. Or in.

Access to the clips on the box behind the brake booster is especially frustrating, as I recall...

[Superman]

Thanks to all. I do need to get in there, as I want to swap out the switches toward the top of the dash (defrost - fog lights - cig lighter). I think. The car is a '78 and I have a set of switches from the '83. The lights, for example, are not working on the current switches.

At any rate, I will be able to see if the clips are still in place. Remove them, check for smooth action of the valves themselves, and the cables, etc. As I recall, as you say, the valves move VERY freely. I actually need to swap out my brake booster. I have a spare and the current one is wet underneath and slowly dripping.

Oh good! Another project!