Hey guys, I'm brand new to this site and any forums, so bear with me if I break any rules or traditions...

This morning I started my 2008 Mustang V6 and there was a definite knock (about 3 knocks per second) coming from inside the center part of my dash, centered above the two middle vents. The knocking lasts about 3-4 seconds and is consistent with each start-up.
I know it was coming from within the dash because I put my hand there and restarted the car... I could easily feel the knocking coming from within.
Does anyone know what this might be? I have had the car for only about 5 weeks now and it's never happened before.

Anyone have any ideas on what it might be?

Thanks for reading!

 

Is the air conditioner on when you start the car? Just a guess but a damper door in the A/C Heater pod.

 

Post above might be correct, my work truck periodically will make a knocking noise underneath the dash and that is because of the a/c, plus there isn't a whole lot of stuff under there that would make a noise

 

yeah, over the weekend I figured out it was only knocking when the A/C was on and the upper vents were on... if I had the feet only or defrost selected, it wouldn't knock. Anyway, any idea how to fix it? Or do I need to just be mindful of my A/C when I start my car?

 

by the way, thanks guys!

 

Maybe someone else had the problem. I'm going to throw out some ideas that might be the problem: Foam padding/insulation on the door dragging or binding; the door could be dragging on something in the pod or could be warped somehow.
I've only had my '99 Expedition apart to see how the doors operate and that was during a heater core change. My '07 doesn't make any noises like that but who's to say it won't start. If it does I'll just have to live with it because taking the pod out or getting to it just because of a noise is not worth the time of taking the entire dash out.