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A tale of unspeakable joy and fixed ACC pixels

20K views 42 replies 17 participants last post by  lee3lions 
#1 ·
I'm proud to say I'm going to contribute a thread about something going wonderfully right with my car :cheesy:

I suffered from missing pixels in my ACC unit long enough, and I decided to do something about it.

Long story short, I've determined that there is a bulletproof method to not only repair a faulty display, but to also eliminate the possibility of future failures.

At the time I was doing the repair I was too tense to stop and take pictures, but I did manage to snap a frame or two of the more revealing steps. I don't have the ability to upload them at the moment, so I'll just breeze through my steps in case anyone else suffering from the same problem wants to take a stab at it for themselves.

THE PROBLEM
The LCD on the front of the ACC unit is controlled by a delicate ribbon cable that attaches to the circuit board behind it, and this cable is not securely attached. Rather than using a socket, the ribbon is simply glued to the board so the contacts on the ribbon are touching a matching set of contacts on the board. After nine or ten years, that glue no longer assures a good connection.

THE SOLUTION
While pulling the ACC unit apart I accidentally yanked the ribbon cable right off the board. It reattached well enough due to the residual glue, but there was no reliable electrical contact. I first attempted to fix this by pressing the ribbon against the board with some foam padding and a few tightly wrapped layers of electrical tape. This failed miserably; with this method I lost what pixels I used to have.

So, I ripped the whole thing apart again and went for broke. The plan this time was to solder the connection and be done with it.

Though the pins are very close to each other and are embedded in plastic, it's possible to make a decent solder joint for the entire cable using some basic instruments, and you don't even need that steady of a hand.

The first step is to remove the ribbon cable completely and apply a little bit of solder to each of the contacts on the circuit board. You do not have to worry about solder clumping up or bridging between pins; it's just important to make sure there is solder on each pin. Next, use a piece of braided soldering wick to clean everything up. By heating the wick and dragging it along the pins, all clumps can be removed and you'll be left with a nicely tinned set of contacts. I was very clumsy when I did this and I can confidently say that the board itself is very robust; there's not really a chance of scorching anything, even if you have to go over it a few times to get everything clean.

After the contacts on the board are tinned, the ribbon cable can be reapplied to the board and should remain in place due to that glue residue.

Now, using that same solder wick to diffuse the heat of the soldering iron, the backside of the ribbon cable can be heated up to seat the connection between the pins. The plastic is pretty temperature resistant, as it turns out. After making a few slow passes, the ribbon will be firmly attached to the board. I still wrapped the board with electrical tape so as not to tempt fate while shoveling the components around during reassembly.

THE CONCLUSION
I plugged her back into the car and let the computers sort themselves out (SID apparently wanted to talk to the ACC before returning control to it), and after a moment everything went back to normal, and the display is perfect!

Since those pins are now affixed to each other instead of just pressed together, there's no chance of the cable coming loose again.

I'll post pictures in just a little bit :)
 
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#3 ·
Okay, no pictures of ACC removal or disassembly, but it's straightforward enough.

Once the boards are all taken apart, this is what the ribbon connection looks like:


The picture above was taken after I soldered it, but it looks just the same as before.


This is what it looks like, more or less, when heating the ribbon after tinning the contacts on the board:

I just kinda massaged the ribbon with the tip of the soldering iron until I was positive that everything was nice and solid.

And the final result:



I'm so happy now :cheesy:
 
#28 ·
Quoting myself here to fix the broken image links from the original post.
Okay, no pictures of ACC removal or disassembly, but it's straightforward enough.

Once the boards are all taken apart, this is what the ribbon connection looks like:



The picture above was taken after I soldered it, but it looks just the same as before.


This is what it looks like, more or less, when heating the ribbon after tinning the contacts on the board:



I just kinda massaged the ribbon with the tip of the soldering iron until I was positive that everything was nice and solid.

And the final result:



I'm so happy now :cheesy:
 
#6 ·
Ero said:
My display doesn't show the econ mode light, and doesn't show the air recirculation light. Also randomly chooses to show rear window heat light. Would that be this issue?
There's actually only one bulb for the entire display.

Your missing graphics are definitely the same problem...

...as far as the defroster graphic showing itself sometimes, I don't think there's a way for this system to fail such that a graphic turns on when it shouldn't. But keep in mind that the ACC will turn the defroster on automatically in certain circumstances. If you hold the rear defroster button down for four seconds or so, it acts like a toggle switch between ACC automatic control (where it will just turn itself on from time to time) and manual control (where it will only turn on when you press the button).
 
G
#7 ·
RITmusic2k said:
There's actually only one bulb for the entire display.

Your missing graphics are definitely the same problem...
That sucks...I'm scared of opening up the A/C unit...and soldering, never done it before..

...as far as the defroster graphic showing itself sometimes, I don't think there's a way for this system to fail such that a graphic turns on when it shouldn't.
oh i mean when I press the button it will sometimes show the graphic and sometimes not.. But it could be the ACC thing and it ignores my buttonpress
 
#8 ·
Ah, gotcha. Well, that is also a symptom of the poor connection. Some of my segments would work when it was cold out, and would then stop working once the cabin warmed up - materials expanded enough to pull the pins apart. It sounds like your rear heater graphic is intermittently connected.

If you've never soldered before, I can understand you not wanting to try this your first time out... do you know anyone who's handy with a soldering iron? I could provide more details if they'd want to take a stab at it.

If no, then there could be other options. I'd gladly do it for you if you shipped your unit to me; you'd just have to drive around for a few days without climate controls.
 
G
#9 ·
RITmusic2k said:
Ah, gotcha. Well, that is also a symptom of the poor connection. Some of my segments would work when it was cold out, and would then stop working once the cabin warmed up - materials expanded enough to pull the pins apart. It sounds like your rear heater graphic is intermittently connected.

If you've never soldered before, I can understand you not wanting to try this your first time out... do you know anyone who's handy with a soldering iron? I could provide more details if they'd want to take a stab at it.

If no, then there could be other options. I'd gladly do it for you if you shipped your unit to me; you'd just have to drive around for a few days without climate controls.
I appreciate the offer but its really not worth it with how it is, I can kinda tell when my defroster is on :)

I'm going to take an electrical engineering course next semester and get more aquainted with soldering....then give it a shot if i feel motivated to.

again thanks for the help
 
#15 ·
arky, I am nearly certain it is used by electronics people to 'wipe up' excess solder placing it on the solder you want to pick up, then you apply the hot iron to the wick, hey presto, nice and clean, no extra solder there. I've not done it, but it looks simple to do. I watched a guy doing it on an instrument, I thought it was a great idea.
 
#18 ·
Yeah, I've always thought wick was more effective and elegant than using solder-suckers (which are like suction syringes, and are kinda cumbersome, and don't work nearly as well).

It's a usually a very fine braid of copper filaments, all of which is coated in soldering flux (a neat goop/resin that makes the solder want to adhere to the copper. Once heated, it literally wicks the excess solder into itself).

I believe the SID fix is very similar to this; I haven't taken a SID apart yet myself, but from what I've seen, the displays are attached in a similar manner.
 
#19 ·
I did this fix this AM.

I can vouch that the solder/wick method does a fine job of retinning the circuit board. You may get some resin on the board, but no biggie.

I made the mistake, however, of using a strong plastic cleaner (used for PCV pipes and the like) to prep the ribbon. It totally etched off the foil run on the ribbon itself.

No big loss as I'd planned on shipping to the ebay bloke in the UK for repair, anyway.

So, the repair is good in principle. Just don't get too carried away and overly prep.

As a footnote, I've pondered doing away with the ribbon entirely and using individual strands of ethernet wiring, instead. They are certainly small enough and if you made a mistake with the solder, simply wick it up and try again. It's too time consuming for me, but someone with more time on thier hands might want to give it shot someday.
 
#25 ·
As a footnote, I've pondered doing away with the ribbon entirely and using individual strands of ethernet wiring, instead. They are certainly small enough and if you made a mistake with the solder, simply wick it up and try again. It's too time consuming for me, but someone with more time on thier hands might want to give it shot someday.
If you're going to go through with that, why not make some sort of quick disconnect system? I'm sure there's a proper male+female end at RadioShack (Or the like) that has enough pins, so you could just connect (example) solder female to the board, and the male end on the ribbon.

I'd give this a go seeing as how Kramer Micro Repair totally fubar'd mine up.

Thanks for the post, OP!
 
#20 ·
The difficulty there is that you're going to have to interface with the ribbon cable at some point. The ribbon is sandwiched between the glass layers of the LCD screen, so there's really n good place to attach the conductors on that end.

Might as well make the interface where the leads are already exposed at the end of the ribbon.

As far as prep work goes, the most I would do is swab the area with a q-tip dipped in rubbing alcohol. When I did it, I didn't even have alcohol - I just dampeded the q-tip with water and just made sure it was all dry before I assembled.
 
#23 ·
In lieu of that, there's a much easier and less damaging method, if your fingers are long enough.

You can remove the cabin temperature sensor cover with your fingers (prying upward gently from the bottom of the cover).

With this cover clear, you can easily pull out the passenger seat heater switch (I use my car key to pry it outward).

Through this hole, you can reach your finger in and push the ACC unit out from behind.

I can do this in about ten seconds, and there's no chance of marring any visible trim pieces by prying with tools.
 
#24 ·
Do you really mean to push the back of the ribbon cable onto the board with the soldering pencil? And it doesn't instantly melt??
 
#26 · (Edited)
That's correct. It doesn't melt - keep in mind, however, that I used a bit of copper braid to diffuse the heat from the tip of the iron. It still got plenty hot, but the plastic showed no signs of degradation. It didn't even discolor :cool:

EDIT: I just realized that the pictures I posted aren't showing up anymore; we recently changed our webserver and haven't ironed out all the kinks. I'll try to get the pics hosted elsewhere :)
 
#30 ·
My ACC (2001 9-3 SE Convertible) is only missing a few pixels. I can't read the first digit of the temperature setting, only the second.

What's the first temperature setting, in Fahrenheit, above the LO setting? I could figure it out from there.

I don't feel confident to take it apart and try to fix it, and it's not missing that many pixels. I bought a rebuilt SID and it works great, but I haven't found any outfit selling rebuilt ACC displays. Anyone know of any?

Thanks.
 
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