Schizophrenic Climate Control? 512TR | FerrariChat

Schizophrenic Climate Control? 512TR

Discussion in 'Boxers/TR/M' started by EZORED, Apr 5, 2020.

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  1. EZORED

    EZORED Formula 3
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    Nov 24, 2007
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    So, all of a sudden, I never know if I am going to get heat or cold air out of my ac ducts. I will say that if the temperature control is set for heat, I generally get heat, but if i ask for cold, it is a crap shoot. I have noticed that the temp dial on the console (Ferrari part 61078700) rotates freely with little to no resistance. When I position it to blue, I can hear the ac compressor engage, and when I touch the ac lines one is hot and one is cold. I am running r-12 and in the past it will freeze me out.
    When I drove the car this morning, (63 degrees outside air temp)all I could get was heat coming out of the dash no manner how I rotated the switch. I just went out to the garage, set the ac to cold and started the engine, at idle in the garage, I measured 39 degrees coming out of the dash (its 82 degrees F outside). next I rotated the switch to heat and quickly heated up to 85. rotated back to cold and temp began to drop back into the 40's. It could be my imagination, but it is like the car senses how cool the outside temp is and will not cool when it is cool out. On the other hand, there has been several times I needed ac and could only get heat!

    What would be the next diagnostic step?
    1. Could the hot water valve be sticking?
    2. could the temp sensor in the dash be bad ( replaces last year by a used part)
    3. could fan motor that pulls air past the temp sensor be bad?
    4. ?
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Pages I38 and I39 in Vol 2 of the 512TR WSM has the (relatively easy to make) resistance measurements at the 6-pin AC ECU connector to check the sensors and temp knob operation. If you don't have a copy, give a shout (I think I have it uploaded to my DropBox, and can get you a link, if necessary).
     
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  3. EZORED

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  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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  5. ago car nut

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    The hot water heater control valve defaults to open. When a temp control ground signal is sent, it closes. I installed a manual valve in mine, never drive when cold out. Yes not correct, but works!
     
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  6. EZORED

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    Ago, that is a great idea, I used to do that in my 70's era Corvette's! I live in Arizona and it made a big difference!!! I think I saw your thread on how to do that using a valve under the dash correct? Ideally an electrically controlled valve in the motor compartment would be the best solution. Too bad the factory default on the TR is open and not closed! Then a simple switch would do the job. What if you ran a separate switch controlled 12v to the valve, telling it to stay closed all the time? When you wanted it to function normally just flip the switch. My concern would be that it could cause feedback to the ecu and burn it up. Steve M, would you have an idea?
     
  7. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #7 Rifledriver, Apr 6, 2020
    Last edited: Apr 6, 2020
    Default open is a TUV (German eqiv. of DOT whose requirements many other countries also use as their own) requirement. If there are system failures it should still be able to keep you warm and keep the defroster functional.


    The valve is easy to get to. You could install a manual ball valve right next to it. It would defeat part of the function of climate control though. While I am not a huge fan of the system when it works correctly I don't see this as an improvement.
     
  8. EZORED

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    I can see TUV Points, but not really a need in Arizona, where the humidity runs 3-15% and temps in the 100+ in the summer! LOL
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    No, no harm to the HVAC ECU to add a manual switch as that's how it sort of works now:

    One terminal (with the M wire) is always +12V with the key "on" (independent of the HVAC buttons).

    The other terminal (with the MB wire) is connected to ground by a relay when the system is "OFF" and connected to the HVAC ECU. When you push any other button, the relay actuates to remove that ground signal and HVAC ECU either grounds it (to close it for no heat) or doesn't ground it (to open it to add heat).

    You could add a switch to ground this MB wire manually (which would always close the hat water valve if the +12V on the other terminal is present); however, if you lose the +12V on the M wire (for example, because the k connector terminal gets frazzled), the hot water valve would still open, but the interior fan blower would stop working, too.

    Before doing anything like this, I suggest you do those resistance checks as the passenger compartment sensor could be reporting a wacky value, or the temp knob could be requesting a wacky temp. Additional, since the minimum temperature on my temp knob is 63 deg F, I think you might only get heat if the passenger compartment sensor really is less than 63 deg F (or reporting a wacko resistance corresponding to less than 63 deg F).
     
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  10. EZORED

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    Steve, I have pulled the HVAC ECU. I was hoping I could attach a 12+ to the MB wire at this point which would keep the hot water valve closed. See attached. access at the hot water valve is very tight. thanks Dennis
     

    Attached Files:

  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    No - connect the MB wire at the HVAC ECU to ground to keep the hot water valve (always) closed (assuming everything else is OK).
     
  12. EZORED

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    Wow that makes it easy. Thanks!


    Sent from my iPhone using FerrariChat
     
  13. ago car nut

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    Put a switch on the ground wire so you can have heat if you need it. Well maybe not in Arizona, Then block the hose.
     
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  14. EZORED

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    Thats the plan. Switch it is!!!
     
  15. EZORED

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    Well the switch worked, but the its caused some problems as the car started puking out antifeeze when ever I stopped on our drive yesterday. I disconnected it and the problem went away. I do not recommend!
     
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  16. Qavion

    Qavion F1 World Champ
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    Is it puking through the normal overflow or from somewhere more ominous?

    Here's my latest 512TR airconditioning wiring diagram which includes Steve's helpful comments about hot water valve control.

    512TR Fig8 Airconditioning Wiring Diagram

    Just wondering if an intermittent evaporator relay "D" could also cause an intermittent problem with heat.

    By the way, which is relay "D"?

    https://www.ricambiamerica.com/car-diagrams/ferrari/v12/testarossa-group/512tr/air-conditioning-unit.html

    Image Unavailable, Please Login
     
  17. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    What is your reference that the HVAC ECU F P/N 61079400 = Bosch 9140010077?

    I have HVAC ECU F P/N 61079400 = Bosch 1147328034
     
  18. Steve Magnusson

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    Don't see how the state of the hot water valve (whether open or closed) would have anything to do with coolant coming out the overflow or not. Are you possessed by a demon? ;)
     
  19. Qavion

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    #19 Qavion, Jun 8, 2020
    Last edited: Jun 8, 2020
    Not sure I remember now, Steve. I just Googled Bosch 9140010077 a few seconds ago and it came up with this Japanese ad for a 512M ECU...

    http://yahoo.aleado.com/lot?auctionID=b238661747

    I understand that all the Testarossa group use the 61079400

    Hardly proof of course. I'll remove the Bosch reference until further details come forward.

    Thanks!
     
  20. EZORED

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    Yes the car was puking thru the overflow. I drove to where we were meeting to start the drive, which was maybe 10 miles. I had not grounded the brown white wire as I saw no reason to do so because the ac was working great. Parked, with no puking or any notice of a problem. Then as we started the drive, the vents start pouring out hot air, so I hit the switch and the heat stopped and I began getting ac again. Then about 15 miles into the drive, we stopped at a light and a car behind be started flashing their lights and motioned me to pull over. I will say that my temp gauge was not working because a wire had come off the pin in the dash when I was repairing a rattle in the instrument pod last week. I did not notice it until later and I had no time to R &R before the drive. So I was not able to monitor the engine temp, which made the whole situation more stressful on the drive. So we reached are destination, we stopped and more puking but not alot. (The engine did not seem particually hot). The car cooled down while we had breakfast and I checked water levels. I added 1/2 gallon of water and made it home. overall drive was 115 miles. Car puked about a quart into my garage floor. Car did not seem hot. That afternoon I refilled water 1/2 gallon, pulled the dash and fixed the temp gauge. Then I remembered the switch which I turned off. The next morning got upstarted the car and the temp gauge worked fine as I drove it about 10 miles and no puking when i got home. Engine temp never went over 90 C. fans worked fine. Putting 2 and 2 together, it seems to be the ground switch or Demon!!!! LOL

    Could it have been some kind of back preasure caused by the hard ground? I though I would buy a new radiator cap today all though the current one was replace on the engine out last year.
     
  21. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Sounds more like maybe some, or all, of the cooling fans weren't working for a time. Shame that your coolant temp gauge wasn't working when you had the problem -- don't see how it could ever "puke" out the overflow if the coolant temp reads 90 deg C. At least now you can watch the coolant temp gauge when using the switch or not.
     
  22. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #22 Steve Magnusson, Jun 8, 2020
    Last edited: Jun 8, 2020
    That does seem a bit sketchy (although the form factor and connector patterns are the same).

    afterburner posted some great pics and info about the 61079400 TR/512TR/F512M family HVAC ECU here (and I can confirm that mine is the same):

    https://www.ferrarichat.com/forum/threads/struggling-with-heater-valve-heater-control-testing-super-stumped.618194/page-2
     
  23. EZORED

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    Started the 512 today, let it idle, finally got to 90c and fans came on. I walked to the back of the car and antifreeze was coming out of the overflow again? Must be a bad radiator cap?
     
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  24. Qavion

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    #24 Qavion, Jun 9, 2020
    Last edited: Jun 9, 2020
    Thanks, Steve. ... diagram updated to show your number. Interesting link... bookmarked for further study :) Might Dennis have the same problem?

    Most of the components in the ECU look easy to replace.
     
  25. EZORED

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    I pulled the old radiator cap off and discovered it had a crack in it and the little center piece had fallen into the reservoir. I had to pump all the green antifreeze out and was able to locate it. luckily it is slightly magnetic and I was able to fish it out!! So my switch is staying in place for future emergencies!
     
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