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HVAC Controls Question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Stoopalini, Oct 17, 2002.

  1. Stoopalini

    Stoopalini 1/2 ton status

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    No matter what setting I put my heater controls on, the air always blows out of every place possible.
    The defrost, vents, and floor always have the same amount of air coming out no matter what the selector is on. The fan speeds work fine, and if I move the selector to the off position, it does turn off.

    Is there a vaccuum line somewhere that controls this? Anyone ever deal with this problem?

    Thanks,
    Thomas.
     
  2. imiceman44

    imiceman44 1 ton status

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    Yes, there is a vaccum line that controls this, it's a black plastic sphere with 2 rubber tubes going in it, if they are there and you have vaccum at that point, then your problem is on the control box under the dash directly linked to the control lever. It's a vaccum switch with about a dozen hoses stuck to it. You should be able to get to it if you remove the control panel. /forums/images/graemlins/thumb.gif
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    The heat control is cable operated.
    Pull the glove box door. The Cable is on the top of box that controls the blend door. Slide the heat lever back and forth and it should be pretty easy to figure out what's wrong. Sometimes the little deal that retains the cable on the arm pops off.
     
  4. imiceman44

    imiceman44 1 ton status

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    Hey grim, he said that air was coming out of every vent, that happens when the baffles that are controled by VACCUM don't operate.
    I know because I had the same problem before.
    I have it now on my oldsmobile too /forums/images/graemlins/frown.gif
    But if he could direct the air to any vent he wanted but still had no heat then I would say it's the cable.
     
  5. Stoopalini

    Stoopalini 1/2 ton status

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    Thanks for the info guys. It ended up being the vaccuum line right behind the air filter housing. The line that goes inside the cab broke. A 2 min repair it's working again.

    BTW: I didn't see the black round reservoir that I expected to see on the passenger's fender well. Instead, there's a diaphram inside the cab, under the dask, mounted to the passenger's side kick panel.

    Thanks again guys,
    Thomas.
     
  6. imiceman44

    imiceman44 1 ton status

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    Well I guess they changed the design in later years but it still was the vaccum line, I thought it would still be the same since my olds (GM) 86 is still the same way.
    Glad you got it fixed.
    /forums/images/graemlins/thumb.gif
    I am not always right but I do get a few right ones:) /forums/images/graemlins/smile.gif
     

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