Chevrolet Q&A

Ask Your Question

1999 Chevrolet Silverado 1500 Question: Heater/AC controller

 

Question

thedudeabides, 5.3L V8, Neosho, MO, September 29, 2009, 12:03
 Rookie

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
Flag This
  • Medium-star Best Answer
    Bret Bodas from RepairPal Test Shop, September 29, 2009, 12:58
     Master

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

    Flag This
  • Reply

    Bret Bodas, September 30, 2009, 09:55
     Master

    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:
    Condition:
    a/c control head flashes, performs erratically or malfunctions.
    Cause:
    light surface corrosion on the control head terminals.
    Correction:
    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.

    Reply
    Flag This
  • Answer #2

    sinautoscan.com September 29, 2009, 18:18
    Profile_thumbnail
     Master

    getting some use parts from ebay

    Flag This
  • Reply

    thedudeabides, September 30, 2009, 05:12
     Rookie

    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

    Reply
    Flag This
  • Answer #3

    Visitor, May 27, 2011, 23:16

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

    Reply
    Flag This