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Thread: HVAC controls

  1. #1
    Senior Member sactodreamer's Avatar
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    HVAC controls

    I'm working on changing over the Fiero HVAC controls and using 91-95 Camry controls for my replica build. I found the following info in this archivies at Pennocks: Anyone ever modify heater controls to round knob style?

    The connector to the climate control PC board has thirteen connections:
    A - Illumination lamp supply
    B - Fan power (hot if OFF not pressed)
    C - Illumination lamp ground
    D - Hot to get DEFROST outlet
    E - Hot to get FRESH inlet
    F - Hot to get BILEV outlet
    G - A/C on signal to ECM
    H - GND for engine cooling fan relay
    J - Hot to get VENT outlet
    K - Engine cooling fan relay enable
    L - Hot for RECIRC inlet
    M - Hot for FLOOR outlet
    N - 12V power to the control unit
    (hot in run)

    I've gotten just about all of it mapped for the Camry system but I need to know what letters H and K do. The way I interpret it is H provides a ground to the coolant fan relay and K provides +12v. I'm guessing that is to kick on the fan when the A/C is turned on.

    Here is the "H" circuit.


    Here is the "K" circuit.

  2. #2
    Senior Member murcie-me's Avatar
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    Generally when the AC is switched "on" on most vehicles, it also activates the electric radiator fan as well even if the engine is running cool.
    Without talent experience is worthless

  3. #3
    Senior Member MacGyver's Avatar
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    Generally speaking, you want to run two relays from your switch to control the ac. One powers the ac fan and activates when you turn the dial to ac when the ignition is hot. The other relay is to control the cycling of the compressor. The relay gets its ground to operate from the ac pressure switches and cycles the ac compressor.

    Sorry I can’t see the diagrams you posted.

  4. #4
    Senior Member sactodreamer's Avatar
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    I'm not sure why the images are not showing here. Try my post on Pennocks: HVAC control swap - Pennock's Fiero Forum

  5. #5
    Senior Member sactodreamer's Avatar
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    Got it figured out. H is a constant ground which provides a ground to K (engine cooling fan on) when the A/C is on.
    Last edited by sactodreamer; 04-20-2014 at 11:06 AM.

  6. #6
    Senior Member RCR's Avatar
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    Cool

    Very cool

    Bob
    Bob custom '84 Fiero SE --->>> custom F408
    http://www.madmechanics.com/forum/cu...ilepic37_1.gif

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