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2003 GMC Envoy Question: Loud knocking in dash when vehicle is started and no air from front vents.

 

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tmlamon, Bangor, ME, November 01, 2012, 05:11
 Rookie

When you start the vehicle there is a loud knocking that goes on for about 1 minute. There is no air coming from the front vents. What is the thing that shifts the vented air around? I wonder if it has somehow become jammed? Air works from floor and windshield vents.

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  • Answer #1

    Greg's Orange Auto (12205 Answers) , Orange, CA - (714) 361-9386
    globalhelper November 01, 2012, 06:05
     Master

    your blend door sctuator has gone bad, that regulates air flow from heater to defrost and a/c. approx cost is 400.00 to replace it.unless its the one that is in the middl of the dash and that one is approx 800.00

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  • Medium-star Best Answer
    csubak30 November 01, 2012, 06:07
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     Master

    Loss of use in the HVAC directional vents will usually mean a bad mode actuator that needs replaced.

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  • Answer #3

    your.mechanic November 01, 2012, 08:19
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     Master

    the blend door broke off...and is flapping inside the car.

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    tmlamon, November 01, 2012, 17:39
     Rookie

    I wonder if there is a way to reach in and remove the broken part without pulling the dash. Not really concerned about the vent but the knocking is pretty annoying.

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    your.mechanic, November 01, 2012, 20:21
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     Master

    There is a way to eliminate that annoying knock, try to access where the door or actuator is and use self-tapping screws to wedge whatever is making noise.

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    globalhelper, November 02, 2012, 05:44
     Master

    this swill stop the noise nut not fix the problem

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