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  1. #1
    qpv8evo
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    Thema heater valve position

    Hi folks,
    Having a bit of trouble with the heater on the Thema (Series 3 turbo)
    It has a mind of its own and only changes from cold to hot when it wants, i can see a control rod moving on the outside when an assistant operates the temp control buttons which leads me to believe that the control panel is working. Does it have a conventional electronic valve on the matrix pipe or is it all done with airflow? If it has a valve does anybody know where it is located?
    Strangely enough it blows much warmer when accelerating hard.
    Thanks in advance
    Gareth

  2. #2
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    Re: Thema heater valve position

    It's a SAAB system that works on blending hot / cold air to get the desired temp. The Positioin of the blending flap is controlled by an electric motor buried in behind the centre air vents, but it can be accesed by removing the instrument binnacle (easy to do)... I am assuming you are RHD.

    If you have a system with A/C you can press Auto and Vent buttons simultaneously an it will trigger a self diagnostic check. The check returns a 2 character code that relates to the problem. If you go to the technical tips section of http://www.lancia-tdc.co.uk you will see an article that I wrote about the testing and codes.

    I would guess you have a temp sensor that is giving a false reading or else the flap position sensor is wrongly alighned causing the temp level to hunt for the desired setting. Acceleration, might indicate that yor blending flap is not connected (Maybe the arm has snapped!?) and the flap is free to swing back and forth as you accelerate / brake?

  3. #3
    qpv8evo
    Guest

    Re: Thema heater valve position

    Many Thanks for the info,I will have to do the diagnostic check.Just to confirm is there not a water valve in the system?
    Regards
    Gareth

  4. #4
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    Re: Thema heater valve position

    There is no water valve, water flows through the heater matrix continuously and the air blender flap mixes hot / cold air to get the necessary temperature.

    If you can see the wire pushing on the lever of the flap in the engine bay, it suggests that the motor is OK, but the problem might be with a cabin temp sensor temp sensor or maybe the air blender flap has broken its connection to the actuation lever and is now "flapping" freely.

    Run the diagnostics and tell us what you get.

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