I'll get in there in a couple days, but I'm wondering if anyone recognizes the symptoms:

It's a very high pitched, constant ring.
Sounds like it's coming from the passenger side.
When the fans are off, the ringing is still there.
When the Stereo is off, the ringing is still there.
It's the same regardless of the vent position.
Seems to only occur with the vehicle running.
Ringing cannot be heard outside the car.

Is there a relay or something in that area?

Possibly. But it's not buzzing. Do relays ring? I've never seen that before.

Figured out it was something on the circuit board of my HVAC control dealy.