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1999 Chevrolet Silverado 1500 Question: Heater/AC controller



, 5.3L V8, Neosho, MO, September 29, 2009, 15:03

My 92 Chevy 2wd and 90 Chevy 4wd pickups both have digital heat/AC controller problems, which is apparently very common for those vehicles. Anybody got a cheap bypass/workaround/suicide solution? ;^(

3 Answers
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  • Medium-star Best Answer
    September 29, 2009, 15:58

    What type of work around? What is the goal here? Have you looked at used parts?

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    , September 30, 2009, 12:55

    I like your style, Dude.

    We have some good Chevy techs on the site, hopefully they will have some info.

    I checked and there is a technical service bulletin: #46-12-02 It refers to a "fix" for some of the problems with these units. I have no idea how well this works, but hope it helps. Here is what is says:
    a/c control head flashes, performs erratically or malfunctions.
    light surface corrosion on the control head terminals.
    remove the a/c control head and while holding the unit with the terminal
    cavity down (toward the floor) so no particles will fall inside on the circuit
    boards, polish the terminals on both sides of the cavity with a lead pencil pink
    eraser. do not use an ink eraser or other abrasive such as a small wire brush
    or sandpaper, etc. doing so will remove the terminal coating and degrade the
    contact surface.
    **performing this procedure, in many cases, will make replacing the control
    head unnecessary.** using this procedure in conjunction with the a/c circuit
    diagnosis found in the electrical diagnosis manual and especially before
    replacing a control head for any reason is recommended.
    after polishing the control head terminals, but before reconnecting, check for
    proper terminal contact as described in the applicable electrical diagnosis
    manual. if contact is good, apply dielectric grease (p/n 12345579) to the harness
    connector terminals. please do not apply grease to the control head.
    service parts information:
    p/n description qty 12345579 dielectric grease from tube as needed
    parts are currently available from gmspo.

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  • Answer #2

    September 29, 2009, 21:18

    getting some use parts from ebay

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    , September 30, 2009, 08:12

    Good questions, bretb! Used heat/ac controllers from junkyards are nonexistent, and those early digital contollers are notoriously problematic, so any one I get is suspect. And since I've got two such beasts, I'm considering a totally different way of controlling the heat/ac, maybe a simple custom control solution from a classic car catalog, JCWhitney, etc.? Any ideas? Thanks for responding! thedudeabides

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  • Answer #3

    Visitor, May 28, 2011, 02:16

    found loose and burned conection behind glove box in a three wire conector where two red wires plug in.easy fix .

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