348 hvac control panel damage? | FerrariChat

348 hvac control panel damage?

Discussion in '348/355' started by Davsk1, Jun 18, 2018.

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  1. Davsk1

    Davsk1 Karting

    May 10, 2016
    155
    Lincolnshire UK
    Full Name:
    Dave
  2. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
  3. ///Mike

    ///Mike F1 Veteran

    Dec 11, 2003
    6,097
    Bugtussle
    Looks for all the world as though that trace on the PCB has been cut away. But if so, why?

    I took a bunch of pics of mine when I had it apart but for some strange reason they're not in my car folder. Sure hope they're on the camera card, but it's at the shop. I'll try to remember to see if any of them show that area of the board if someone else can't provide a better answer.
     
  4. whyte

    whyte Formula Junior

    Apr 25, 2006
    404
    Merritt Island, FL
    Full Name:
    John C
    Hard to tell from the picture, but almost looks like a failed solder joint, and some damaged traces that were repaired. Or, the diode got very hot and caused the coating on the traces to lift.

    Many times when joints fail like this, they increase resistance and generate more heat. Vibration and thermal cycles over time can cause failures.

    That's a hot section of the board.
     
  5. Davsk1

    Davsk1 Karting

    May 10, 2016
    155
    Lincolnshire UK
    Full Name:
    Dave
    Thanks for sharing, It's hard to tell but maybe could be a fusible link on the board that has blown. I'm still not confident enough to put a link in there though :/

    The only problem i3n trying to chase is an intermittent problem with the fan randomly ramping up to full speed. I have a temporary hard wired solution to cut the fan off when the problem occurs.

    It's hard to see how this diode link could be related to the problem but who knows
     
  6. Davsk1

    Davsk1 Karting

    May 10, 2016
    155
    Lincolnshire UK
    Full Name:
    Dave
    Yes please if you can, it would be good to get a concensus before I go for reinstating a link
     
  7. whyte

    whyte Formula Junior

    Apr 25, 2006
    404
    Merritt Island, FL
    Full Name:
    John C
    Fan power module is often the root cause of this. I spent a long time chasing issues for blower turning on, fuses, panel resets. All caused by voltage regulators in the power module. There is a great rebuild thread here:

    https://www.ferrarichat.com/forum/threads/348-havac-problem.531155/page-3

     
  8. Davsk1

    Davsk1 Karting

    May 10, 2016
    155
    Lincolnshire UK
    Full Name:
    Dave
    I will investigate that, I had discounted this module because the fault is intermittent so had assumed the chips are fine but it could be a dry joint. The fault seems to change sometimes by wiggling the plug at the back of the hvac panel but this isn't certain. I really wanted to repin the plug at the back but can't for the life of me seem to get the blighters out.
     
  9. ///Mike

    ///Mike F1 Veteran

    Dec 11, 2003
    6,097
    Bugtussle
    Dave, I finally found the pics I took when mine was apart. Looked at them all carefully and that diode is not shown in any of them. I elected not to separate the two main boards since the unit has been working flawlessly and I didn't want to tempt fate. Only had it apart because I could hear a loose part inside when I removed it to refinish the upper console panel. Turns out there was a screw floating around inside. Didn't see any place it could have come from and it appeared to be like the ones that secure the back cover, so it's likely that the screw had been inside since it was originally built!

    Anyway, I'm sorry the pics didn't provide the info you need. I really thought they would until I saw that I'd never separated the boards.

    Some notes for the archives to anyone thinking to disassemble their climate control unit: Make sure not to lose any of the return springs for the buttons (a couple are highlighted with red arrows in the bottom pic). I found broken posts on the back of the some of the buttons-- the material appeared to be cast acrylic and it was very, very brittle. I managed to re-secure them using an appropriate glue, but you want to be very careful when operating and working on that unit.

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  10. whyte

    whyte Formula Junior

    Apr 25, 2006
    404
    Merritt Island, FL
    Full Name:
    John C
    It may not be the module, but as an added data point, that is exactly how mine was. Started out A/C was fine. Then some days it would not turn on, others blower full bore, or even heat full bore with no controls. Jarring the panel a bit would often cause it to work again. I suspected a loose connection also. So I took the panel out, went over it for hours under the scope, checked all the pins, ran external power to it. No issue. Back in the car, worked fine for a day and then, right back to craziness. Although I haven't confirmed this with the schematics, I suspect (in my case) the faulting power module is pulling too much current and putting the panel in a weird state. Jarring it may have shorted something to cause it to reset. Who knows.

    I actually have the power module apart on my bench right now. I'll follow up with my findings.
     
  11. 2000C43

    2000C43 Rookie

    Nov 28, 2009
    36
    Sacramento, CA
    Full Name:
    Dean Sioukas
    Looking forward to your findings. Your description of intermittent issues but then days (or even weeks) of normal operation sounds familiar.
     

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