I already ran a search, and didn't find anything too similar, so I have to ask...

2006 X6 4.4 with 26k miles.

When the FAN is on, you hear an odd hum / whine / low pitch whistle in the cabin, that actually corresponds to way you actuate the gas pedal.

The more gas, the more pronounced the noise. Off the gas, VERY little noise.

Fan off, noise gone.

It's subtle yet annoying. It's my wife's daily driver & she's getting up-idy.

Any thoughts?

VR/SLD in CT