88 K1500 has defrost only.

[DeCaff2007]

Howdy all. So, I've recently acquired an 88 K1500, regular cab, 5-speed. No A/C. The interior looked and smelled like it had been sitting in a field somewhere since about the mid 90's, but ironically, it ran and drove no problem.

I tore the interior apart to get the smell out. Found many, many (dead) things that had made me glad I didn't turn the blower motor on. I tore the dash apart, but didn't disturb the heat/defrost cables, nor any of the contraption that sets head/feet/defrost. Everything is scrubbed clean and back together now. First thing I did was try the vents. Blower motor works but it clicks. Whatever. The bigger problem is that no matter what range I have the heat/def set on, it only comes out the defroster and that slider is HARD to push.

What should I be looking for?

P.S.: I was also able to tear the dash apart and put it back together without breaking anything that wasn't already broken!

 

[DeCaff2007]

Since my first post here seems to be getting less-than-stellar replies, I took another look under the dash. Turns out that I only had to remove the metal box that the radio plugs into to be able to see the problem:

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See that arm and the cable attached to it? There's a gear behind there that that arm lines up with.

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So that gear isn't actually missing a tooth. It's designed that way so that the arm will stay aligned. Problem is, it jumps the teeth very easily. Fortunately, if it jumps the teeth, it won't break the gear. It will, however, force the vent slider (on the dash) into the DEF position and it will be stuck there. Hence, my original problem.

To fix this, there's a single 7mm screw securing that arm to the heat box. Remove that, and remove the cable from the arm, as well. You should see this:

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If you can't turn that gear with minimal effort by hand, then the arm/cable won't do it's job (and the arm/cable will jump the gear teeth, locking the vent selector into the "Defrost" position) It's a simple matter to clean and lubricate the two spring arm assemblies in the pic above (shown in the "Head" position, as opposed to "Feet" or "Defrost") The white over spray in the pics is white lithium grease. It comes in an aerosol can, same as PB Blaster.

So then I re-attached the arm/cable and tested the slider on the dash. I now have the ability to select where the heat goes.

Oh and one other thing. The above pics are from after everything was cleaned. Trust me, you all did not want to see the pics where everything was still dirty.

 

[Erik the Awful]

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I apologize for not responding to your first post, but I really didn't have any ideas for you. My truck has auto air, and I barely know anything about that system. The circled cable end in the pic above needs to be secured in that clip, but you can see that it's pulled back. That might be part of your difficulty in moving the slider.

 

[DeCaff2007]

Correct. I did try to push the cable back into that clip. Feels almost like the cable is melted right at that spot. A replacement is due. Now... where to find one? Everything I've come across in the junkyard is either missing or electronically controlled.

 

[Erik the Awful]

Pop that metal clip out, use some pliers to crimp it a little tighter, and reinstall? Or maybe wrap a short strip of sandpaper around the cable?

 

[Eveready]

I too had nothing to contribute as the inner workings of that HVAC setup is a complete mystery to me. Thankfully mine works. I do admire anyone who can take that panel apart without breaking stuff. GM expected these trucks to last 3 to 5 years not 33 as in your case. Did your truck never have AC or just removed or not working? If it ever had AC in the past the restoration of that is a project unto itself. Also considering your location what shape is the frame in ? Good luck and welcome to the forum.

 

[DeCaff2007]

AC was never equipped on this particular example. The frame isn't in too bad of shape. I'll need to replace the rad support, though.

About that cable, I want a new one. Seeing as how I don't have a radio and the box that the radio plugs into is removed, I can reach down by the heat box quite easily to give that arm the extra push it needs to direct heat where I want it... that is until I find a replacement cable.

Now, a side note, if there was an affordable, efficient way to convert to dual climate control, I'd do it.