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Defrost

Discussion in 'The Garage' started by Blazer1AB, Oct 29, 2005.

  1. Blazer1AB

    Blazer1AB Registered Member

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    I had to put a heater core in my blazer last weekend and ever since, the defroster hasn't worked. I havent had a lot of time to check it out, but I have basically found out that the door that is behind the middle floor vents doesn't do anything when i switch the control to defrost. I will inspect the vacuum lines tomorrow, but if those are fine, do you think its the little silver diaphram or is something with the actual door broke? I've reached in there with my hand it its feels like its spring loaded- so is this right?
     
  2. jeeptuff

    jeeptuff 1/2 ton status

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    Mine does the same thing, no defrost..
     
  3. nstarry

    nstarry 1/2 ton status

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    there is a another post on here about this everybody says its a vaccum line but they wont tell you wich one it is yet
     
  4. jeeptuff

    jeeptuff 1/2 ton status

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    So, which is it?? Come on somebody is holding out on us!!!! :saweet: :1zhelp: :ears:
     
  5. big d

    big d 1/2 ton status

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    im guessin its the lil plastic clip on the door that changes the direction of the fan air.the rod is fastened to it and the clip has a sheat metal screw passing thru it. the clip usually brakes right in the middle. its only like a 1.50 or sumpin like that from a g.m. garage. im gonna go pick myself up a couple here pretty soon and fix mine. hope this helps.
     
    Last edited: Oct 31, 2005
  6. GM Man

    GM Man 1/2 ton status

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    I had the same problem on my 78 Jimmy and I found out that if you unplug the vacuum canister on the passenger side firewall, then nothing wants to work. Check this out to see if yours is unplugged.
     
  7. nstarry

    nstarry 1/2 ton status

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    the controls themselves are activated buy vacum , were is the vacum coming from ? I found the vacum line coming out of the fire wall right buy the heater/ air cowl so I could fix it if i had any idea wear to hook it up to :(
     
  8. Muddytazz

    Muddytazz 1 ton status

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    Runs off of a vacuum port off the backside of the intake manifold right between the carb and dist.



     
  9. nstarry

    nstarry 1/2 ton status

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    thanks man
     
  10. anjieandjohn

    anjieandjohn Registered Member

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    Big d, you got a part number for that little plastic piece? I took all my ducting out today and guess what, I have that little broke plastic piece. Where did you get it from? Thanks.
     
  11. big d

    big d 1/2 ton status

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    i dont have the pn but its only available from the chevy dealership. just tell em what u need. my dealership has 4 and im buyin em all while they r still available. :rolleyes:
     
  12. anjieandjohn

    anjieandjohn Registered Member

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    Went and got that little plastic piece for the door...cost $1.68 with tax....I put one on and now the heat blows like the dickens...with no blow by to the vents. Now, when I switch from heat to vents or defrost, it doesnt switch. Isnt there a vacuum switch in the ducting somewhere?
     

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