CUTLASS HVAC Head Unit Inside Car

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RotaryLvr

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Nov 22, 2022
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I had great success from this community understanding the vacuum hoses under the hood of my 1984 H/O. I was able to understand a bit where a broken vacuum hose should be attached.
Now on to the next issue and I hope that I'm not going to get anyone upset asking all these questions. I'm new to the this platform.
I'm trying to figure out how the head unit for the HVAC is repaired...the bottom lever (cold/hot) will not go all the way to the hot or right side. I think the unit comes out from the front, but I don't know anything after that or how to fix it. ideas on this issue would be appreciated. In the mean time, I will try to educate myself on this topic and try to search for some information. I think I found a youtube on how to take the unit apart. I'll take a closer look at that as well and grab the control unit from a Buick I took out and left at the Picknpull. At the very least, I'll have some parts.
Ralf
 

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84 W40

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Dec 9, 2009
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Ask all the questions you want, myself and the other members will help you.
Looking at the pictures you provided that cold hot lever controls a flapper door by a cable. Open your glove compartment look above it but straight in with a flashlight. Move the lever from cold to hot you should see a cable moving attached to a white or black lever. It's possible that the flapper door is binding or the cable broke or something else is broken.
 
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ck80

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If you do a little exploring you can probably see some of what's going on without removing too much.

Step 1) empty your glove box all the way out.
Step 2) look on the side of it, you should be able to see where if you press on the edge, the protruding clip/lever on the side can pass beyond the dash opening, allowing the glove box door to drop all the way open and point downwards, hanging from the hinge to let you see inside.

Looking inside - you will see a long thin black wrapped wire coming from behind the radio, and, a thin grey wire with a loop on it comes out of the end. It circles around a plastic post, and, is held down by a press down retaining circular clip. As you move the hot/cold lever back and forth the metal wire slides in and out of the sheath, pushing and pulling the plastic post. It makes the lever arm the post is molded into move. That arm in turn moves the ac blend door back and forth, deciding does air pass through the condenser, or, the heater core, before going through the dash duct.

Usually it is in that area you find your problem.
 
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RotaryLvr

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Nov 22, 2022
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Good grief, you guys know your stuff and quickly with answers for the inexperienced as well! I will look at this tomorrow morning!
 

ck80

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Good grief, you guys know your stuff and quickly with answers for the inexperienced as well! I will look at this tomorrow morning!
It's very simple, and, sometimes your fix will be as easy as removing that circular clip gently as not to break the plastic, removing the looped wire, move your temp slider all the way to the end, then slipping the wire back on the post.

If it moves end to end normally at that point you're done, put the clip on and close it up
 

69hurstolds

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Jan 2, 2006
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To pile on what ck80 said, if you unclip it at the pivot and the lever doesn't move end to end any more, then check the cable for something bent, or it could be something in your head unit keeping it from moving. Slightly possible there's a lever pin inside that drops and hangs up the unit not letting it go all the way over. Not saying this is the issue as it's very unlikely, but I've seen it ONCE on a brand new head unit.

Now, IF you find out some sh*t is broken under there...

you may need a rod clip and pivot lever if that's an issue

The cable is talked about here in the first minute. But it's a good video overall for learning about the HVAC stuff without taking your dash apart to see it.

You cannot get the lever out without first unhooking it and turning it in a way to line up the tabs on the pivot pin with the cut tab holes in the HVAC housing. So don't force it if you have to replace it.
 
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ck80

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To pile on what ck80 said, if you unclip it at the pivot and the lever doesn't move end to end any more, then check the cable for something bent, or it could be something in your head unit keeping it from moving. Slightly possible there's a lever pin inside that drops and hangs up the unit not letting it go all the way over. Not saying this is the issue as it's very unlikely, but I've seen it ONCE on a brand new head unit.

Now, IF you find out some sh*t is broken under there...

you may need a rod clip and pivot lever if that's an issue

The cable is talked about here in the first minute. But it's a good video overall for learning about the HVAC stuff without taking your dash apart to see it.

You cannot get the lever out without first unhooking it and turning it in a way to line up the tabs on the pivot pin with the cut tab holes in the HVAC housing. So don't force it if you have to replace it.
BUT, I will say this, if for whatever reason you think you need to replace the pivot arm (doubtful, usually it's the threaded rod that goes into that u shaped plastic clip that you realign and snap back into place) such as if the plastic post where the looped wire attaches with the round retaining clip breaks off because you're too aggressive with the needle nose pliers) you can usually modify the original plastic piece.

I had one break. And I was unwilling to give the business to the company in 69hurstolds link because... well, multiple reasons.

1) back in the day they parted out cars other guys held titles to, without going through any proper ownership process first - how do I know? I bought one of them with a title, in a title required state. 2 days later I went back to pick up the car... it was gone, lager to appear on the gbodyparts website being 'parted'..... so. Same time they bought an intercooled gn from a guy who told me when I looked at it 'I don't have the title, I'm selling it for my friend that is in prison' and parted that one out, saw it on their website. Not sure what the guy told them, but, it was also sketchy as hell. There's that to their business practices.

2) customer service is very hit or miss. Read about complaints. Some guys get lucky. Some.... don't. I've heard anecdotes about things but... I'll leave that to the reviews you can search.

Anyways, anything gbody parts makes can be gotten elsewhere most times. In the case of that part, I drilled out the post at the base and made a hole, then matched the post thickness to a small bolt. A thin thin washer each side of the plastic, bolt through, one nut, plastic post now metal. Slid the wire on, another washer, another nut, was a permanent repair, worked great. Cost under $2 at home depot instead of paying $40 to a company that operated like that.

So, if something goes wrong, let us know, sometimes there's cheap fixes.
 

RotaryLvr

Not-quite-so-new-guy
Nov 22, 2022
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Actually that's a scary story. I'm still have to look at this issue. Time of course is the issue. I hope I don't break anything.
 

69hurstolds

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Jan 2, 2006
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TBH, I didn't look who was selling those parts.

Full disclosure, I've mostly had crappy service with gbodyparts.com. Others swear by them. IMO, what Brothers Automotive Parts (BAP) did to the 60s/70s Cutlass era car scene, Gbodyparts.com does for the late 70s-80s G-bodies scene. Both tend to blame everything and everyone but themselves when things go wrong, both claim to have all you ever need from them, and most interestingly, both seem to move every so often and complain to the mountain top about how much of a pain it is to move. You almost wonder if they're related. BAP is far worse, IMO, though.

If you luck out and they have it in stock, and they actually send you the right part, it comes out ok. But if you have to return something or something goes wrong with your order, it's not an easy process. Or it never was when I used to buy from either one of those entities.

To be fair, I do not know if gbodyparts.com ever got the message and tried to improve the attitude and service as it's been years since I bought anything from them, and that was when they would sell NOS GM parts. Leopards don't tend to shed their spots, but you never know.
 
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69hurstolds

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Now, to get to the head unit to remove it, if needed:

Remove your lighter from the socket. Then, gently pull the corners of the plastic woodgrain plate surrounding the radio and remove. There are some tension clips that hold things down. Don't get crazy or something will snap, and it won't be good. But sometimes, it takes a firm tug to get them loose. You now can see the 4 screws for the head unit, 2 on either side. Remove those and slide out the unit, then disconnect the 2 electrical plugs, and 2 vacuum plugs from the back of the unit, and then turn it over and carefully remove the cable end from the actuating lever. Just be careful and not yank or twist stuff to hard, and you should be ok.

This video is from some crazy Olds guy, oldsofb who makes detailed videos of stuff he does to his car. While you may not be rebuilding yours, it gives you insight on what's in store for you if you take your head unit out and you can see the stuff you'll be dealing with.
 
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