Odd clicking from behind upper center of dash above ~30mph

[Jamoke2006]

For background, I'm a pretty new Pontiac Vibe owner, just got mine around 2 months ago and it was in pristine condition. Only 120000 miles on it. It's a 2007 base model with the monsoon speaker package.
It started first around late November. I first checked to see if it was the air conditioning recirculator as that's a common issue but it was not as pressing the button on or off did not change it. And neither did turning the air con off or on affect it. It stops when the car is at a lower speed and occurs roughly every 4.5 seconds exactly regardless of speed as long as it's above 30 mph. Any idea what it could be?

[andrewclaus]

The moving parts for the HVAC are lower, below the radio. There are several movable doors to direct the different modes. Maybe one is loose, and affected by outside air under pressure at higher speed. Have you tried all modes, in addition to recirc? All fan speeds?

Also verify all the HVAC modes work correctly.

The blower motor assembly and cabin air filter are easy to access by removing the glove compartment. Sometimes outside debris gets stuck in there.

That area can be accessed by pulling the silver dash trim above the radio. It's held in with spring-loaded clips, and there's an electrical connector. You can at least take a look (while someone else is driving).

If all else fails, try a little "percussive engineering," if you haven't already.

[Jamoke2006]

The noise itself originates behind the emergency lights button and the back window defroster button. I have tried all HVAC modes and they work as intended. Nothing makes it stop besides reducing the speed. Something that does seem to affect it, oddly, is repeatedly pressing the back defroster button. Sometimes it causes it to stop if I do it enough. On another note, the back defroster button is sticky and doesn't always pop back up. The back defroster itself is functional and works.