strange noise

[w261w261]

I have an intermittent noise that is not loud, and comes from a unit of some kind that is behind the glove box to the far right. It isn't loud (if you have the radio on you can't hear it at all), and if I didn't know the car so well, I probably wouldn't have noticed it either. It isn't related to the heater fan, because when the fan is off, it's still making the sound. That sound is something like (perhaps) a damper motor trying to work, and then giving up. It is electrical and not vacuum-related, because it is going when the engine is off (it does not happen in the "acc" position, but does in "run" w/o the engine being on. Sometimes it does this, sometimes not.

Anyone have a clue? I know the description sucks. Can someone tell me what the unit is right behind the glove box on the far right. It's maybe 6" across. Thx.