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A/C / vent issues

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by crashfirepm53, May 5, 2004.

  1. crashfirepm53

    crashfirepm53 Registered Member

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    My 91 burb. is blowing low out of the dash vents and the majority of the pressure comes out the floor.Plenty of volume.I have it apart but i cannot figure out what closes the vent valve.I can manually close it and it damn near blows you in the back row!!! Any help???Trying to save some cash for what is probally an easy fix.It all appears to operate by vacuum I think??
     
  2. namkrow

    namkrow 1/2 ton status

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    you might have a vaccum leak or a disconected vacuum line.

    Check all the connections and check the actuator with a vacuum pump to make sure it's working properly (maybe a bad diaphram)
    -T
     
  3. daleearnhardt01

    daleearnhardt01 1/2 ton status

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    Check the little clip that connects the rod to the door in the lower vent housing. It controls the door that directs air to the floor or defrost/AC vents. Lots of times they break and its only a 96 cent dealer item..
     
  4. crashfirepm53

    crashfirepm53 Registered Member

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    Which vacuum controls Diaph. controls it?The lower center one or the far right Diaph. by the blower? The rod for the vent door is only 6'' long and doesn't appear to attach anywhere else so I'd think it is vacuum controlled??
     
  5. daleearnhardt01

    daleearnhardt01 1/2 ton status

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    You have to take all the ducting out to see what Im talking about and once you do its easy to see.. /forums/images/graemlins/waytogo.gif
     
  6. crashfirepm53

    crashfirepm53 Registered Member

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    I have all the ducts out and the 2 plastic clips look good.When i move the switch on the dash to the right from off through heater, the lever behind the control slides to the right spinning something that appears to go to 6 vacuum lines.I do not know how to test these.Should i be suctioning or pushing air through each hose??
     
  7. daleearnhardt01

    daleearnhardt01 1/2 ton status

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    Hmm I guess it is a vaccum issue then. I really never dug into that part ot he system when I fixed mine. If you do a good search on here there is some good stuff about just this topic though. Sorry I cant help any further.
     
  8. crashfirepm53

    crashfirepm53 Registered Member

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    I saw a earlier post about an A/c control problem that was talking about the orange and black striped vac. line on the pass side kick panel.He followed it through the firewall to the cowl???I can see where it goes behind the ductwork mounted to the firewall but not through it.Also I cannot see where it comes out at.Any better description??I think I have the same problem since my control only blows on high and doesn't appear to be any vac. anywhere.
     
  9. daleearnhardt01

    daleearnhardt01 1/2 ton status

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    Hmm I think I remember seeing some pics of the vac lines coming out of the firewall like in the middle into a little T fitting. Id do a search and see what happens..
     
  10. crashfirepm53

    crashfirepm53 Registered Member

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  11. crashfirepm53

    crashfirepm53 Registered Member

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    Problem solved!!!!My mechanic friend said to check the vac. at the engine.The line directly to the a/c control was fine but where it comes out of the manifold and T's for the TBI and washer the hose was deteriated and collapsed.
     
  12. daleearnhardt01

    daleearnhardt01 1/2 ton status

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    Sweet man I figured it could be at the T
     

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