temp control 89 5th ave

[FredMcJoe]

mmm! Getting closer... isn't there a listing of the electrical connector part-numbers in the wiring diagram sections of the body manuals? Seems like I remember seeing that somewhere.

For my car, it's a trouble with the connector. My door motor works fine when the connector moves slightly, and the top tab of the pinch-together set of tabs that releases the connector from the servo is broken off altogether now. Thanks for the files.

 

[BudW]

The only place I recall seeing part numbers is either on TSB’s (which I don’t see any for this system) or in the Parts book (below link).
The problem with Parts book is it is not specific as to what each item is for and only the popular connectors are still available (about 2/3rds of the parts have not been available, from Chrysler, for a long time.

Also see https://www.forfmjbodiesonly.com/classicmopar/threads/1984-electrical-connectors-pins-bulb-sockets-part-numbers-and-so-forth.6642/
BudW

 

[FredMcJoe]

Man, that's a noisy little servo. Got mine working, thank you to all who've posted pics and descriptions, made short work of it.

I could not tell exactly what the problem was, however.I had the typical 'temp lever won't go all the way to the right... the temp sliding switch inside had developed some dirt or something stuck on the track it slides on. I used brake parts cleaner and then some white lithium spray grease to get smoother action out of it. It works well now, without that mechanical resistance at the "85" end. So this is one component that could have been at fault, tho I doubt it. The actual sliding switch slid to cold without working the blend air servo either.

Next was the connector. The top clip of the two pinch-together clips broke off my connector. I zip tied it around the rear securing post on the servo. This could have been the fault point, one connector tang-tab had a lot of burnt carbon deposits on it. I bent down the connector tabs to ensure contact.

The blend air door moved without resistance.

I removed the servo box, it's just one bolt at the front and a twist fit for the securing post at the back. Wait.. let me pause to marvel at Chrysler's ease of access and simplicity of repair. ....
ok... I removed the servo's top piece once it was off the HVAC box, and spun the little motor, it got the gears moving and all looked well. I reassembled it and it worked. Slowly rotating the blend air door as needed precisely to the positioning of the temperature control lever..... grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr and back to warm ...grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr and a little cooler now.. grrrrrrrrrrrrrrrrrrr

Next step, vacuum side of things... Or... this red vacuum hose.. why is this one red? Where did it connect to? Why is it hanging out of the vacuum connector all alone? Does it have an end? ...more to come.

 

[MoparKidD-4]

This is good to know for the future in case the ATC in my '88 Fifth Ave does the same thing. Although I think that will be a while, it works flawlessly now and doesn't make any noise either like you describe. In fact I was shocked at how silent and responsive the whole system works when I first got the car, it's truly the first type of climate controlled car I've driven that is possible to get the PERFECT temperature coming out the vents that doesn't fluctuate constantly simply by adjusting the temp lever. Man I miss analog controls in cars...

 

[FredMcJoe]

Like the sand through an hourglass, its just a matter of time

My 5A had a hard life, it spent most of its life in Los Angeles, and from what I can see it must have been an outdoor existence. The top tab of the pinch-together connector socket to the servo was the one that broke off, the tab that sits closest to the top of the dash panel top was evidently more brittle than the one slightly more protected on the underside.
I suspect this car sat in the sun a lot and this probably aged the servo more-so. The top of the vinyl roof is also especially aged.

Next up, installing 1/8'' rubber tubing inplace of the vacuum hose assembly. I should check my check valves, too. My buttons no longer move the air to the right places.... it was fine before I started fixing the servo, I imagine my moving stuff around broke the plastic manifold assembly the 7 hoses fit into. Fix one thing, break 2

 

[FredMcJoe]

The integrated circuit board has limited value in an automobile, contrary to popular belief

I like how the Spark Control unit picks up the ultimate timing point and how its related to how fast the gas pedal was mashed to the floor. And Delco's Twilight Sentinel automatic lighting. Aside from those two major advances in motoring comfort and safety, to me the IC, digitized function design is pointless in a Chrysler. Instead, all these 10-20 year old $300 inoperable FWD Chryslers have become failure prone with these body control computers, etc. It's automotive technology regression, the computer

 

[MoparKidD-4]

I'd say Electronic Fuel Injection is a good one too... not much besides that.

 

[gomopar89]

IME with my 5th aves, when you slide the temp lever hotter or colder, this sends current to the electric motor on top of the blend air door to open or close depending on your desired temp. Mine got stuck on full heat and the motor never worked again, so I had to disconnect the heater hoses and put them in a loop. Then I added a brass plumbing valve, from Ace hardware, to the inlet hose to the heater core. This way I could at least manually control the flow of hot coolant to the core.

Of course these blend air door motors are pretty much non existent, and I did not feel like digging it out and taking it apart. So my brass valve did the trick!

 

[BudW]

I have a box of “bad” blend air door servo motors. Even tried to fix a couple – to no avail.

The "add-on" water shutoff valve works fine – but I wouldn’t keep it shut off for a long period of time. Been my experience that a lack of coolant flow though the heater core causes them to leak a lot faster (from rust/corrosion).

The SATC (Semi-Automatic Temperature Control) system was designed to have coolant going through the heater core full time – except it shuts off flow during “Max A/C” operation or when “Off”.

What I have done, is two things. First I purchased a 12 volt timer set to 4 minutes. The timer powers a vacuum solenoid (from a 4*4 front differential vacuum actuator solenoid). The vacuum solenoid shuts off manifold vacuum to the hot water valve for the first 4 minutes of vehicle operation, After 4 minutes, it allows for full engine vacuum to the hot water valve which should (if valve works correctly) stop any coolant flow through the heater core. Note: this was a temporary fix – but works fine for 10 months out of the year. Note: I did "plug" the (hard) grey vacuum hose/line going to the hot water valve, so I could use it in the future.

Second, my permanent fix. I removed the A/C servo, its short piece of wiring harness, removed the in-car temp sensor, Aspirator, its hoses and ambient temp sensor. I then replaced the A/C control head with a non-SATC unit. I also found cable that fits early ’80's FM-bodies (not sure about J-body), part number 3847430 (note – I’m not 100% sure this is the correct part number), lever 3846007 (also not 100% sure of this part number), Clip (p/n 6031132 – which came with my cable) and nut (a common ¼” hex nut.

I found another cable from an ’80 Aspen – but it was broken (so no spares).

If a person wanted to get rid of SATA, then I recommend finding an ’80 or early '80's FM (and maybe J) body and get the A/C control head (you only really need is the top lever of the control head), cable, lever and its nut. Then remove a few of the un-needed parts and presto, you now have working A/C and heater (but just not automatically controlled) - providing your A/C or heater was working correctly to begin with.

Now, if it was just this easy to get A/C working on my ’77 wagon . . .
BudW

 

[FredMcJoe]

So do the motors fail due to worn carbon leads which could be replaced? Mine started working after I worked it a little though I am beginning to suspect that was a temporary fix after the last drive I had. Can ;a similar new motor replace the old?

 

[BudW]

Most of the ones I have are locked up solid.
I don’t recall about what I’ve done on the others (been too many moons ago).
BudW

 

[GregG48213]

got stuck on full heat

I had the same problem with my '88 Diplomat. The servo worked fine; the blend door itself was stuck on full heat. I fixed it by grabbing the rod that stuck out (for the servo) with vice grips and gradually working the door back and forth. I wondered if it was stuck from the factory, since the car was only five years old when I got it. The previous owner may have tolerated the problem because the Air Conditioning still worked on "Max AC".

 

[BudW]

Max A/C still has air flow through the heater core – but the hot water valve turns off any coolant flow through the heater core.
BudW