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'90 Suburban a/c air vents & switch question..?

Discussion in 'General Chevy & GM Tech Questions' started by omnisi, May 17, 2009.

  1. omnisi

    omnisi Rockstar 100 Posts

    I just got the a/c on our '90 Sub repaired (compressor and all) and I noticed that when the a/c switch is in the "Normal" position, that the air flow still comes out as if the switch were on "Bi-level"....about 50/50.

    Where do I need to start, or what do I need to do to get all/most of the air to come out of the dash vents when the switch is on "normal" ?


    BTW - Defrost works fine as does the "max"...
  2. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    If I could see i pic of the vent controller it would help, just cant picture its setup, I know its the two sliding levers though
  3. omnisi

    omnisi Rockstar 100 Posts

    Yes, its the slide levers with the pattern:

    max - normal - bi level - vent - heat - defrost ...in that order, and the "normal" position is acting like the "bi level".
  4. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Your bi-level setting I am guessing isnt for the air, just cool or heat and your normal and max setting is specifically for ac, so this is by design, max is full ac.
    Last edited: May 17, 2009
  5. omnisi

    omnisi Rockstar 100 Posts

    According to the controller, the a/c incorporates the "max-normal-bi level", then "Vent-heat" together, the "defrost" separate. So, the bi-level is part of the a/c control.


    Thanks for the help!
  6. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    My 85 chev truck only had normal and max for he ac so i am guessing one of the blend doors is not moving correctly

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