82 mirada heater blend switch

mopops

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82 mirada with AC sliding blend switch lever -controls amount of heat-not working how do we fix this problem? trouble shoot--parts. thanks and happy holidays to all
 

Aspen500

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ASSUMING the Mirada HVAC is the same or very similar to an F-body, my first guess is the control cable either came off at the control lever or at the heater box, or (and this is common), got kinked between the lever and the cable housing. Could also have the cable housing come detached from either end. Once bent, the cables never really work again, even if you try to straighten it out.
 

Aspen500

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Well, you know what they say about assumption............:oops:
All I can give you is that on newer vehicle's (like 2000's and up), 95% of the time the temp can't be controlled (or the mode), it's the door actuator (motor). Very rarely is it a problem with the controls.

You know which actuator motor goes bad? If there's 5 of them on the HVAC plenum, and 4 are fairly accessible, it WILL be the one you have to take the whole instrument panel out to change. I blame that darn Murphy:p
 

AJ/FormS

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IDK if this will help;

My Dad had an 84 FifthAvenue ,that had that problem, and when it started, simultaneously was heard a constant tic-tic-tic from deep inside the dash. It turns out both were related. I took out the glove box, and some otherchit and found, on top of the heater box ,was an electrically controlled gear box going tic-tic-tic-tic continuously. It had stripped it's gears trying to move the stuck door it was attached to. I think that mightabin the blend door. Anyway, I removed the gearbox, manually unstuck the door, put it where I estimated I wanted it to be for full heat(it was late fall), re-positioned the gearbox to match, screwed it back on, and left the device unplugged.That worked for the long Manitoba winter.
 

mopops

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IDK if this will help;

My Dad had an 84 FifthAvenue ,that had that problem, and when it started, simultaneously was heard a constant tic-tic-tic from deep inside the dash. It turns out both were related. I took out the glove box, and some otherchit and found, on top of the heater box ,was an electrically controlled gear box going tic-tic-tic-tic continuously. It had stripped it's gears trying to move the stuck door it was attached to. I think that mightabin the blend door. Anyway, I removed the gearbox, manually unstuck the door, put it where I estimated I wanted it to be for full heat(it was late fall), re-positioned the gearbox to match, screwed it back on, and left the device unplugged.That worked for the long Manitoba winter.
thanks i will try to take out glove box i don't hear the clicking but your help gets me closer to the door thanks happy holidays
 

AJ/FormS

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In Dad's car, it, was pretty tight for room above the device, to remove the fasteners. I used a special ratchet that works different from the normal ones. Instead of ratcheting the handle in the usual way, you spin the stationary handle, which turns the head. It's pretty slick and has got me out of quite a few jams. It was a gift to me from my son, a lotta years ago..
 

MiradaMegacab

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2A07AD35-58D0-4943-8406-2DAD1F8BD86E.jpeg
not cable --electric
That would be “ATC”
 

Rustyroger

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In Dad's car, it, was pretty tight for room above the device, to remove the fasteners. I used a special ratchet that works different from the normal ones. Instead of ratcheting the handle in the usual way, you spin the stationary handle, which turns the head. It's pretty slick and has got me out of quite a few jams. It was a gift to me from my son, a lotta years ago..

I bought a Craftsman twist handle ratchet maybe 9 years ago. Invaluable working in tight spaces!.

Roger.
 

mopops

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sad to say i am still at this problem, i put it away for the summer to do -paint job -motor rebuild ,everything but heat n now i need heat. has anyone had and fixed this problem?the renco valve is working -- the sliding heat lever is electric-not cable-and seems to be working i just can't seem to find what it controls -or i am looking at it and don't know it tks for any help
 

MiradaMegacab

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ATC
Automatic Temperature Control is what you have as there’s no cable control. The ATC has a black box servo (mounted above the blend doors rod) to open and close the blend door.
See the above pic
 

MiradaMegacab

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I haven’t done one in years.....
It is bolted to the top of the heater cote box.
I’m sure others will chime in....
 

mopops

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i have back issues so that's why i asked ,if the dash has to come out and if i can still get the part? i might not be able to get it done tks
 

BudW

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Chrysler used the term SATC (Semi-Automatic Temperature Control) for M and J-bodies.


I have touched many a servo motor for those. Chrysler quit making them in the early ‘90’s and finding a good one is … Hard.

Every time I go to a Pull-a-Part, I grab the ones I can get. I have a box of ‘em that need testing – but honestly, it has been a long sense I’ve seen a good one. I’m sure someone can fix one, but I hadn’t been successful, yet.

My recommendation is to make sure yours work first. If it doesn’t, then find a cable and control head form an F-body or non-SATC M or J-body and change it from SATC. I have changed my ’86 Fifth Ave to cable control but converted my control head so it still looks like SATC.


You need to remove the dash pad/top and the glove box portion to access the servo. After you do that, you can barely see the servo at that time. Remove a triangle shape duct and a piece of plastic covered insulation (for servo noise). There is a ¼” head screw at top that needs removed. The servo will pull straight up and out. Unplug once removed (if not testing it first).

To test, turn car on (engine can be off), and turn control head one way. Wait a moment then move the other way. You should hear a buzz/grind as the motor inside moves. If nothing, then you can get out a test light to make sure it has power. Almost all the servos I’ve worked with in last twenty+ years are bad.
BudW
 

AJ/FormS

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My Dad had an 84 Fifth, and I was able to get to that device without removing the dashpad; but there was no way to remove that 1/4 " headed screw, cuz there is maybe an inch of access room above it.
My test was to move the control lever all the way to one side, while touching the ATC. I guess the device has some form of limiter in it that is supposed to shut it off when it reaches the limit of travel. Dad's wouldn't shut off; so I could feel and hear a snapping inside the unit. When I finally got it out and apart, I found a little nylon gear in there with some teeth wore off. Since it was winter, I repositioned the door to full heat, indexed the ATC to match, unplugged it from the electrical connector and screwed it back on, Great now I got heat.
The stump of the blend door does not stick up above the surface of the heater box;( or maybe it does just a lil) and it's it a bear to grab hold of and turn. So, there is nothing to attach a lever to, for to rig a cable..... in case you might be thinking along those lines.
Dad went to hospital that spring and died by July, so the car never again drove in summer.
Then it sat on my yard for a couple of years.
Then I sold it for the value of the four very low mileage tires that Dad had installed on it the fall before he went to hospital, and the nearly new, 3yr old battery. And yes I told the kid, and his dad, about the ATC being rigged.
I wouldda kept that car for myself but it was to me, about the ugliest babychit butterscotch-yellow, inside and out, and I just couldn't get past it. Otherwise, it was a very nice car with what looked like leather seats.
 
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