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Defroster

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Itali83, Mar 2, 2001.

  1. Itali83

    Itali83 1/2 ton status

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    My 87 Jimmy has A/C. My question is that does anyone else have a weak defroster? When I put it on defroster most of the air comes out of the upper A/C outlet that is right above the heater controls. My fan and switch work fine so it isn't the fan not blowing enough air or anything like that. I know that it has vacume acuaters that change from floor to defrost. Do you think this is it or something else? I don't really want to take my dash off again because the next time I do it, I'll probally break something or want to put a new dash in while I'm at it. When I had the dash off last time, I did notice that the tubes are all hooked up (if my memory is correct) so I don't think that is the prob either. Thanks
     
  2. bushwacker

    bushwacker Registered Member

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    Itali83, sounds like you may have a vacuum leak in one of those tiny vac lines. When they start to get old , they crack and leak, and are hard to detect. Hope this helps. PS: whats the Itali for? Italiano?
     
  3. Itali83

    Itali83 1/2 ton status

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    The Itali is for Italiano. I wanted Italy83, but it wouldn't let me, so went with Itali83. But same difference. I was kinda figuring of the vacume acuators or the lines, just hoping that some may have had other failures. Thanks again.
     
  4. TheGeneral

    TheGeneral 1/2 ton status

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    The quickest way to solve find out where the problem is, ie it is something to do with vacum or binding in the vent that changes the air flow from main duct, is to use a hand vacum and put the requred vacum on the actuator on the back of the HVAC controls. You will quickly be able to find out if it is a line, diaphram, or binding in vent. I had this same probem, and was not looking forward to tearing out dash, just so I could replace and mess with a bunch of air hoses, turns out is was a little piece of plastic on the vent door that conects the linkage rod to the diaphram. Junk yard part for 50 cents and good to go. Hope this helps.

    Joel

    If you ain't hurt, you ain't playin' hard enough.

    The General
     
  5. Itali83

    Itali83 1/2 ton status

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    I didn't really think about any obstructions. Did you still take off your dash pad though?? Also, what is the HVAC controls? Thanks.
     
  6. TheGeneral

    TheGeneral 1/2 ton status

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    HVAC controls are the heater, something, air conditioning. I am assuming on that one, as most mags refer to the control for the heater, fan, and such as HVAC. There is probably more to it than that. You don't have to take off the dash pad, but you will have to take off the gauge cluster panel, in order to undo the screws to get to the back of the HVAC controls where you can unplug the vacum line from the actuator and plug in your hand vac pump. The other thing you will have to do is take off the floor vent spreader, so you can see the door that opens and shuts when you change settings from defroster, to heater, to vent/a/c. By the sounds of your problem, there is either not enough vacum to close and open the door all the way (thus some going to defrost and some panel vents (or floor), or something is wrong in the door area, such as was my case with the broken plastic piece. Hope this helps, and it is a good afternoon project if y ou get strarted in on it. The best feeling after you have it fixed is that you will have done it yourself instead of paying someone else to tell you what is wrong and then fixing it. Have fun.



    Joel

    If you ain't hurt, you ain't playin' hard enough.

    The General
     
  7. Itali83

    Itali83 1/2 ton status

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    Thanks, The next time I've got time and feel inspired I'll take it apart and see what I can see. Thanks for the help, and hopefully something is obstructing instead of having a little line cracked. Thanks again.
     
  8. Derf00

    Derf00 1/2 ton status

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    I have the same problem plus my heater core is leaking. While I was taking the duct apart on the inside, I found the plastic horn, that attaches to the door that controls where the air goes was broken. Hurray, I can fix two problems at once.

    Derf00
    54684font color=""> http://www.derf00.coloradok5.com
     
  9. Whassup

    Whassup 1/2 ton status

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    HVAC is Heater, Ventilation and Air Conditoning

    "There's NO replacement for displacement!"
     
  10. prjt_blzr

    prjt_blzr 1/2 ton status

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    It sounds like the plastic clip holding the selector door has broken. This is located behind the 90 degree duct that sits just to the left of the glove box. Remove the two 5/16 screws at the bottom of the duct and the single 5/16 at the top center of the duct. When you remove the duct from the panel you will see a vacuum actuated door. Near the top center of the door is a plastic clip that holds the actuator rod to the door. This clip frequently breaks and does not allow the door to close completely. So you get airflow from the A/C vent and from the defrost. I usually use two small pieces of sheet metal bent to the proper shape to fix this. Good Luck.
     
  11. Itali83

    Itali83 1/2 ton status

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    To find that 90 degree bend where the vacume acuated door is, do I need to take the dash pad off or is it on the floor where I can get at it without taking stuff off?? Thanks for the info.
     
  12. prjt_blzr

    prjt_blzr 1/2 ton status

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    The easiest way to get to this is to remove the glove box. The duct is just to the left of the box. It will be very apparnt what this is when look. You should also be able to see the two lower screws if you look at the large black box for the heater and A/C stuff against the firewall.
     
  13. 82K5

    82K5 1/2 ton status

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    i had the same problem a year ago. i couldn't get the damn thing to flip the door open. what happened was when i put my intake on i had removed the vacuum hose off of the ball canister under the hood and because the work got finished in the dark i missed it when i was done.



    Phil from K.C.
    1982 K5 Silverado Blazer
    Built in Flint, Michigan-January 1982
    Kansas City = Great B-B-Q.
     
  14. Itali83

    Itali83 1/2 ton status

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    I found out that the little plastic piece that is screwed on to the flapper door was broken, thanks a ton guys, I would have never though to look for that!! Thanks again!
    -Ben-
     

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