heater control cable fix?

TDS 854X4 · March 4, 2002

Hey all!

Well, if any of you remember following my progress (lack of, actually) in trying to get some more heat in my '85 pickup truck, I found the problem. Now I need to find a good solution.

Turns out that the temperature selector lever, that slides from hot to cold, was not operating the door far enough to TOTALLY close out the cold outside air. Last night I took the glove box out, and disconnected the cable. Then manually opened and closed the door, by turning the arm that sticks out of the top of the heater core enclosure box.

And it was cranking out some good heat. But here's where I ran into trouble. I figured that the cable needed to be shorter to pull the door closed all the way. It's got factory curled ends that are held on the posts with little push-on washer type things. Anyway, in trying to re-bend the cable end, it snapped right off, no doubt due to age and temperature. I have a new one on order from my local dealership, that I hope too have in hand in a few days.

My concern is, if the new cable is too long, like what I had, what can I do to adjust it? Was my idea of putting a new bend on the end wrong? Is there a better way to "fine-tune" the cable operation? Don't know how many people have ever worked with something like this. The cable is held into the heater control module with a red plactic clip that seems to snap in place. At the other end, it has the same red plastic, that's screwed to the core enclosure. Neither appears to have much adjustability. Anyone have any ideas, or tricks that they've used? I'd appreciate any and all help. Thanks!!

76BBSub · March 4, 2002

I haven't fooled with these things very much, but it seems that on the heater boxes I've messed with that there were several different mounting positions on the lever. That way you pick the one that has the correct adjustment for your particular cable. Another possibility is that your cable had stretched from years of use, and the new cable will be the right length right from the start.

If neither of those apply, I think that carefully bending another coil onto the end should work, but I'd hate for you to break the new one too...it's a tough call.

Jeff

TDS 854X4 · March 4, 2002

Thanks for your reply, Jeff.

Well, in my case there didn't appear that there were any options for mounting, at least not at the control end. Maybe at the end behind the glove box.

I was working in the driveway, last night, in the dark. I was probably quite a sight for the neighbors ;) , out there in the running truck for about an hour, in 3 degree weather!

I ordered the cable from a local dealer, and the guy I talked to thought that the little plastic brackets at the ends might be adjustable, but wasn't sure. I guess I'll know for sure when I get the new one, and can look at it while I'm sitting inside, not laying upside down under the dash. Have I ever mentioned how much I hate working upside-down?!?!?

At lease there's a fair amount of room on the floor of these trucks.

95Yukon · March 4, 2002

I thought there was a place to do an adjustment on these where the other end (opposite the control end) connects. From the ones I remember, there is a circle bend in the hard steel cable end which hooks onto the lever and controls that door, then there is a small bolt holding a bracket which holds the outer housing of the cable in place. I thought you could loosen that small bracket where it pinches down onto the outer part of the cable and slide the cable to adjust it.

If it's not adjustable there, you might be able to just make a small bracket with a hole to hook over the door arm, and a slot (for the adjustment) where the cable attaches (using a small bolt and washers)

Those "cables" are like hard steel wire, and made to push and pull so they break pretty easily if you try and bend them, but I suspect the new one will hook right up and work correctly if they ordered the right one. I think the only adjustment is where the clamp holds the outer part of the cable at the lower end.

The only other thing is, the flap on the door may not be indexed correctly on the little arm lever thing if it has worn or slipped. I'm not sure how those actually connect to each other. Well, at least the heat problem is (almost) solved so you can at least wire it to stay in the "heat setting" until the cable is hooked back up.

TDS 854X4 · March 5, 2002

95 Yukon,

Sheeez, for a guy with a new truck, you really know these older ones! Like you were looking at it as recent as I did, I am impressed!!

It did look like there might be some room to adjust at the "door" end. I did wire it in the heat mode for now, since we've just had a cold snap, at least there haven't been too many of them this year.

I hope to get that new cable tomorrow or the next day, and have this back together over the weekend.

95Yukon · March 5, 2002

Glad to hear the heat is working now, I had a feeling it was just the door not closing since you said in the other post that both the heater hoses were warm which would indicate flow, and pinpoint the door as not directing the airflow through the heater core.

Well, I wouldn't say my truck is new, it's a '95, but my two previous trucks were 91 and an 84 fullsize Jimmys and I had the same heat problem on a few other Chevys I owned so I remember working on all them pretty well. Sometimes the door would stick and when the control handles get pulled it either slips the adjuster or bends the cable, throwing the door out of whack. You can usually spot that happening when you put it to "cold" and it hits resistance before the slider is all the way over to the left. When that happens, the hot setting is only closing the door about halfway, then the air finds the easiest path to flow, which is straight in instead of through the heater core, and then your driving with gloves on scraping the inside of the window as you drive. I used to live up north so I also remember that well, but in Florida, the only concern is if the A/C is working.