Hey Vetters

I have an '85 with a slider control **** that is difficult to move from the cold to hot position and vice versa on the HVAC console. The '85 has a mechanical cable which operates the vent door, not the electrical operated version. I have read a number of posts and came up with a couple of 'possible' solutions.

- a sharp bend somewhere in the cable that runs from the HVAC console to the blend door bracket
- a rusty pivot pin at the blend door bracket
- something catching at the mechanism on the HVAC console

I just replaced the heater core and installed new plastic clips at each end of the vent door rod.

Has anyone had a similar problem and found a solution or have any other ideas?
I haven't had a chance to investigate these possibilities yet and would like to have all possible fixes before I tear into things - again.


rear clip at vent door

front clip on bracket

bracket with cable attached

HVAC console. The lower slider **** is the one difficult to move.


In hindsight, I should have greased the rear plastic clip also, sprayed the vent door hinges with a shot of WD40 as well as the hinge pivot pin. Replacing the heater core was a &%^$#@ pain of a job. I won't be going in to lube the rear clip or hinges.

While everything was apart, with the new clips installed and only the rod connected, I was able to pivot the hinge effortlessly to open and close the vent door. As soon as the cable was attached, the slider got difficult to move.

Appreciate any ideas that might.

Cheers
Brad

 

Update: I removed the cover on the evaporator box in the engine compartment. I was able to clearly see the heater core, evaporator, vent door and if I hung upside down from my knees, the vent door rod and clip.
I was able to McIvor a length of straw on the end of the WD40 spray tube and soak the clip and vent door hinge. This may have made the heat control slider easier to move or it may have been my wishful thinking. There is still significant resistance when moving the slider **** from left to right and back.


vent door rod and clip soaked in WD40

underside of clip and bracket

vent door hing gap at top, soaked in WD40

Still looking for thoughts from anyone else who has dealt with this issue.

Thanks

 

Can you disconnect the cable from the bell-crank, or remove the screw that holds the cable jacket retainer to the bell-crank bracket? If the lever moves freely with the cable disconnected it's something in the heater box, bell-crank, or blend door. If not, the cable may be faulty. Sometimes it can be lubricated, sometimes the cable or jacket is damaged.

 

When the dash was disassembled and the cable was not connected to the bell crank during the new heater core installation, I could effortlessly move the bell crank, rod and vent door assembly.
I connected the cable and that's when I noticed how difficult it was to move the heat control slider ****.
I'm leaning towards a problem with the cable and will investigate that. I will order a new cable.
I have to make an adjustment to the clip position on the vent door rod anyway as the heat slider **** comes to a stop short of the far left position. When looking thru the hole at the top of the evaporator box, I could see that the vent door does not completely close with the slider in the hot position. One or two turns on the rod clip should fix that problem.
Thanks again for the input. Now is just finding the time to do it.
Cheers