So I am having an issue with a hissing noise coming from behind the center of the dash, near the A/C vents and NAV system. I thought maybe it was the A/C, but when I turn it completely off, the sound still remains. When I turn the car off, the hissing remains for about 3-5 seconds.

Any ideas what this could be?

 

Snake?


Or a leak in a hose?

 

leak in a vacuum hose that actuates the dampers in the HVAC system perhaps