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Ventilation

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by WELLH2O, Mar 9, 2000.

  1. WELLH2O

    WELLH2O Registered Member

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    Location:
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    When I switch my heater from coming out at the floor level to coming out of the vents, (going from heater to vents)and even when I put on my defroster the air does not change (it sort of comes out of all of them at the same time. Is there a butterfly valve that controls this? Could this valve be my problem and if so is it hard to get to? If this is not my problem, what could it be?
     
  2. Esteban86K5

    Esteban86K5 1/2 ton status

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    Location:
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    I was having that same problem untill I took my whole heater/vent assembly out to change the heater core. I found a system of vents that switch from upper to lower when you move the lever. well the mechanism that moved the "butterfly" was brokrn and just spun inside of it. I modified it with braces and bushings so it would work properly. It was a process but now my vent works perfectly. Good luck,

    Esteban
    SEMPER FIDELIS TO MY BLAZER
     
  3. Mr Red

    Mr Red 1/2 ton status

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    Location:
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    Could be what Esteban says or a loss of vacuum for vacuum motors. Do you hear a slight hissing sound when you move from heat to vent to a/c; or to defrost? That would be normal. My '86 has two small vacuum motors that control dampers inside the heater box. One's at the end near driver side & one is on top of the box, under the dash. Make sure they're hooked up with hoses.

    If they are, make sure the hoses on the back of the heater control haven't worked loose. You'll have to remove the instrument panel cover to remove the bolts holding in the control assembly or you may be able to see/feel behind the assembly w/out removing it. If everything's hooked up, I'd put a vacuum gauge on the line to each of the vacuum motors. Work the heat/vent/a/c selector and look for vacuum on the line for each motor. If they both have vacuum, one of the vacuum motors is bad. How to tell which one, I don't know. There might be a diagnostic test for them in a Haynes or Chilton.

    Good Luck,
    <font color=red>David, '86 K5</font color=red>

    Have you driven over a Ford lately? No, but I feel like the Duct Dog answering all these HVAC questions.
     

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