Hello all,

I've searched the forum and online without any definitive answers, just some could be's among various GM vehicles beween 2006-2008. Anyway, I have a 2006 LT that has a intermittent knockng coming from under the dash on the passengers side when I first turn on the ignition. If I just turn the key to the On position it will knock slowly about 10 times, then stop completly. If I turn it all the way and start the vehicle it will knock quickly about 10 times, then stop. Sometimes it will do it once in a while, sometimes it will do it for a few days then stop. I found an Impala site that said it could be an a/c flapper actuator making that sound, but I also notice that when the knock stops the airbag test indicator light on the dash stops blinkng. Coincidense? I would greatly appreciate any information you all can provide before I start going into the dash blind. I really do not want to take a bunch of stuff apart that didn't need to be.

Thanks......

 

Weird. From your details I think my 09 did the same thing a couple days ago. I thought at the time it was my oil pump clattering. Red doesn't leave the barn very often, so it's not started regularly either. My reoccurring problem is loosing the click sound of my blinkers. Weird.

 

Just an FYI... I did some rooting around under the dash and confirmed that the random noise is coming from the HVAC/Air Inlet Blend Door Actuator. Should be a fairly easy fix with a $50 replacement part.