Whirring sound

While I was playing with my scanner with the key on engine off. I notice that there is whirring sound coming from the dash on the drivers side. The sound continues until I either start the motor or turn off the key. Can anyone tell me what that is? Heater motor is off so it is not that.

Thanks

In my T1N, having an intelligent scanner (such as the DAD) attached changes "normal" behaviour.

The T1N has a tiny fan behind the AC panel (draws cabin air into the panel to sense the temperature)

--dick