HEATER/AC CONTROL -1990 TESTAROSSA QUESTIONS | FerrariChat
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HEATER/AC CONTROL -1990 TESTAROSSA QUESTIONS

Discussion in 'Boxers/TR/M' started by rudy355, Feb 14, 2010.

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  1. rudy355

    rudy355 Rookie

    Sep 27, 2008
    11
    Connecticut
    Full Name:
    Rudy
    #1 rudy355, Feb 14, 2010
    Can anyone explain what the function of Ferrari P/N 127014-Power Transistor is for? Also, is it mounted in the interior of the blower box? Or, the exterior? I was led to believe that if the power transistor fails, it affects the operation of the fan speed control. Mine only works with the fan speed control turned up all the way with the blower at full speed. I have no incremental control of fan speed. Any help would be appreciated.
     
  2. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
    6,712
    Lakeland FL
    Full Name:
    Shamile
    #2 Shamile, Feb 14, 2010
    Dear Ferraristi,

    Don't worry...you're not alone.

    This is a common issue and does go in some depth. I would do a "search" on "TR power transister...TR fan speed control.

    There is some very good reading there. I remember one thread with Rifledriver and Steve M chiming in on all the functions and tracing down the wiring for Kerry W


    Oh....welcome to the board !


    Shamile

    Freeze...Miami Vice !
     
  3. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
    6,712
    Lakeland FL
    Full Name:
    Shamile
    #3 Shamile, Feb 14, 2010
  4. Shemmer

    Shemmer Formula Junior

    Jul 8, 2007
    623
    Toronto
    Full Name:
    Rob
    #4 Shemmer, Feb 14, 2010
    I think I can finally offer some valuable information on this topic since my 90 TR experienced the exact problem. Long story short, I removed the transistor which controls motor speed and found that since this transistor is designed to get very hot it had melted the small plastic washer/spacers causing it to loose contact to it's own chassis ground. The transistor did not fail but lost ground and stopped working. I put new spacers in and cleaned and tightened the ground terminal and problem solved.

    Hope this helps.

    Rob
     
  5. Mr.Chairman

    Mr.Chairman F1 Rookie

    Mar 21, 2008
    2,987
    New Jersey
    Full Name:
    Robbie
    #5 Mr.Chairman, Feb 15, 2010
    Rob.. how easy was it to access to power transistor. Is it as easy as removing the center vent and walla.. its right there or is it more? Any photos? I have the same issue and Dave Helms may have easier option.

    R
     
  6. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,873
    #6 jselevan, Feb 15, 2010
    Rob - great work solving the problem. However, the small plastic washer may have been a mica insulator, commonly used on power transistors to insulate the device from the mounting chassis. Mica conducts heat well, but acts as an electrical insulator. The transistor is not designed to get hot...it does so as a consequence of the power dissipation. Failure of the insulating washer may have led to a decrease in heat transfer (microscopic peaks and valleys as the washer distorted).

    What did you replace the washer with?

    Jim S.
     

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