HVAC Control Head Unit LCD Repair

[Bigbeardbiii]

I used the instructions and pictures provided by Ron Beckett to replace my head unit bulbs several years ago and it work masterfully (Thanks Ron)! However, recently my LCD glass plate has been only revealing intermittent parts of the temperatures numbers, etc... I have made extensive searches here for more on replacing and/or repairing the LCD without a total head unit replacement (serious $$$$$$)! Due to the cost, I was fairly certain that someone here had repaired instead of replacing their existing unit. Anyway, the pictures that Ron had included on the bulb replacement also showed the inside of the unit but there are some further, more detailed questions that I need answering if possible. Therefore, I have included one of Ron's pictures revealing the inside of the unit and the LCD glass as well as picture's of mine in which my questions lie: 1. the vertical copper lines on the head unit which connect to the one's connected to the LCD glass appear corroded, any suggestions on what to use and if cleaning them is possible and 2. when refitting the LCD glass does it fit snug into the white plastic clips on all four corners of the white box that holds the bulb or if not, how does it fit there properly for replacement? Any thoughts, knowledge, would be GREATLY appreciated! Also, while I still have the unit a part, if anyone would like me to take additional pictures, let me know and I'll be glad to post for you.
Thanks,
Dean

[Jos Geuze]

Hi

This post explains it all:

Climate Control Fix (pictures)

Regards

Jos

[spikemd]

I did that fix and it has worked great ever since. Just be gentle taking everything apart. Good luck.

[marty_nz]

That linked thread worked a treat on one of my older P38's that had that issue too...

If you have some corrosion on the ribbon connector, then I would recommend removing it . I did some work in my BECM where there was some corrosion - used a small scalpel blade to carefully scrape corrosion off of the tracks (I mean really carefully so I didn't damage anything else) and then sprayed some WD-40 in there to drive out any other moisture and used a Q-tip/cotton bud to wipe away any other surface corrosion.

In the other thread, someone said they used acetone.. you could also use electrical contact cleaner, or isopropyl (rubbing alcohol) to clear the corrosion before continuing with the steps mentioned.

Let us know how you get on.

Martin

[Bigbeardbiii]

Well, I tried! As you can see from my initial posted pics I took it apart. I then cleaned the copper connectors and ribbon w/alcohol and a Q-Tip (it took forever to get all the grime off the connectors but it finally came off. It was pretty difficult to get much off the ribbon due to it being so flexible. Anyway, I did so and put back together and plugged her in and guess what? The LCD was worse than it was before as far as how much it revealed (spotty, etc..)! I did noticed that by pressing on the bottom of the outer plastic, just below the LCD screen made it get better, therefore, I do still think there's hope. In the thread that Jos was so gracious as to send me the link to, I noticed that the original post by Daniel stated that he was going to place some rubber over the silicon piece that presses down on the ribbon to give it added pressure against the copper and even posted a picture but in the picture I wasn't able to see or determine how/where the rubber was placed nor the thickness, etc... of the rubber. Therefore, I have disassembled the unit once again in hopes that someone, hopefully Daniel, can give me some direction on it as I don't want to try a piece and it not be positioned properly or not think enough, etc... and have to disassemble again as the minute screws don't take much to strip when taking it apart. Any assistance or other recommendations would be greatly appreciated as I'm starting to get REALLLLLLLLYYYYYY agitated!

[marty_nz]

I think that the piece of rubber that he glued is was on the back side of the HVAC faceplate, so it's sandwiched between the plastic trim, and the front of the LCD, it give more pressure onto the conductive strip.

[Bigbeardbiii]

Marty, thanks for your thoughts, however, in the original post Daniel submitted someone replied that it is important that the white/clear silicon piece be placed onto the LCD ribbon properly (i.e., only one way) due to the vertical lines impressed in it. They mentioned the lines are faint (hard to see) and could be further currents. In giving it a good look all the way over it, I do see the lines but I think they have simple been impressed into it due to that side being the one that was pressing against the ribbon. If so, then the silicon piece should be replaced so that side is the side pressing against the ribbon because at first glance at the piece it appears to be an even sided horizontal and triangular piece but again in looking more closely at it the sides are shape slightly different and there is a tit in the center of one end of the triangle which could only mean that it is there to secure the silicon under the white plastic piece that has the tits on either side which go through the holes in the ribbon and into the motherboard to hold it in place (which is reverse placement of the silicon piece in the pictures Daniel provided and if the aftermarket rubber piece Daniel placed in to add extra pressure is below the silicon then the silicon won't be touching the ribbon and it then its tit will not have enough clearance to seat in the hump in the center of the white plastic piece that holds the ribbon in place. Further, Please see my last post on the problems I'm still faced with after following Daniel's directions and pictures on the LCD fix. I read Daniels directions and viewed his pictures on how to take a part the unit and place the white silicon in place above the ribbon for the LCD plate. However, the pictures were a bit blurry and the one about placing extra pressure on the ribbon by adding a piece of rubber wasn't clear on where to place the rubber. Additionally, due to the off centered 1/2 circle cut out of the plastic plate, which is green on one side and white on the other, his picture shows it to be placed on the top but he has the green side facing inward. To me, in order for the 1/2 circle being removed from it only makes sense for the plate to be flipped over in order for the 1/2 circle cut out to have a purpose (i.e., there is a white plastic tit off center to the right on the top of the white plastic bulb housing as well as for the white silicon to be most effective by looking at it closely there are vertical linear grooves in it on only one side. This would make me think that they have been imprinted on it due to that side being laid down on the ribbon. Lastly, the white silicon piece also has a tit in the top center of it which would only make sense to me that it it there to slide under the white plastic piece that has a hump on the top center of it (this is the piece that has a tit on either side which goes through the holes on the ribbon to hold it into the motherboard. If so, from the pictures he submitted, it appears that his white silicon piece is being placed in backward as well as the green/white two sided plate between the light housing and the LCD plate. Does anyone have any thoughts on this because when I pulled mine a part initially, the LCD plate fell forward as well as the green/white two sided plate before I could catch it to keep it in the proper order for refitting purposes. Thanks, Dean

[Bigbeardbiii]

Since, after cleaning the copper verticals on the board as well as the ones on the LCD ribbon (both with alcohol and Q-Tips), refitting and I had no improvement on the numbers on the LCD I tried what several others used to clean theirs, Acetone! Guess what happened, not only did it clean any residue off the ribbon but it apparently ate into the ribbon because now where the vertical lines were is not black stripes it is clear. Therefore, after refitting and testing the LCD the numbers are now worse!!!! Guess it is a lost cause now!!!! Oh well, I tried. I guess it's time to dig into the billfold for a large sum of money and pay for a new one as I don't know what else to do!!!! Any thoughts on last gasp efforts to salvage it or someone trust worthy enough that if they say they have a used one if perfect working order that it will be and for a decent price? Thanks, Dean

[ghur]

Dont despair. I have done the same but I still sorted out the problem using the rubber band trick. Get a rubber band similar to the pic. You need to use one that has the same width as the silicon strip. Cut a piece the same length as the strip and fit it against the electrical ribbon and fit the silicon as usual. The rubber band should give the extra pressure required to get the screen working again. I have used different types of solvent to clean the tape and have found that you must use something that leaves no residue. You may need to dismantle it a couple of times to get it to work.

I have repaired a few with the rubber band and all have worked.

[Bigbeardbiii]

Thank you. Now that I have had several hours away from the **** thing I'm willing to get back into it and try something else before giving-up on it. Thanks again and I'll let you know what comes out of it! Dean

[Rogan68]

Not having pulled one apart before (although it is on my "to-do" list, a good tool to use to clean brass/copper connectors is: a pencil eraser. I've cleaned many computer/electrical contacts with a pencil eraser, in the past.

[omarawatch]

Just wanted to follow up on this - I had a lot of problems with this before I was successful and here's what I realize. The rubber silicone is NOT conductive, it's just applying pressure to the ribbon cable. I found that DIRECT pressure on the ribbon table didn't fix it. What I found what I had to flip the silicone piece OVER so it pressed LOWER on the glass, where the ribbon cable starts to bend around the glass edge. This pressure pressure point change was the magic cure for me.

** I didn't mention in the other thread, but I did add a thin later or rubber-band stripped to the length of the glass, glued to the PASTIC FACIA to add additional pressure back against the glass across the bottom edge of the LCD glass. This extra pressure was likey noticable. Consider painting the rubber band cause you can just BARELY see it.

Now i just hope it lasts.

Good luck to you all with this repair. The other thing is , I'm not certain the ribbon cable is ever supposed to be removed from the glass or the circuit board - that adhesive on mine is darn strong, and was clearly going to destry the conductors in the ribbon so I wouldn't advise trying to remove it ever.