"Whirring" Noise Behind Dash on Passenger Side (2009)

[Dragline]

For the past few months, I've noticed a whirring noise coming from behind the dash on the passenger side of my 2009 Mariner. For lack of a better description, it almost sounds like a loud hard drive or a quiet printer running inside the dash. (To clarify, I don't have the nav system, which I understand is equipped with a hard drive.) The noise occurs when parked or driving. At first, I thought it was something with the A/C, but the noise continues with that (and the stereo) both turned off.

Has anyone else experienced a similar problem?

I'm driving an '09 Mariner. It's front-wheel drive with the 3.0 engine.

Any thoughts are greatly appreciated!