Hot and Cold Air Problem

On my 01 it seems I either have a ghost or a real problem. I sometimes hear a strange clicking or mechanical noise under the dash. Sort of like a servo moving back and forth. I thought it sound like the vents or such moving when the air controls are adjusted.

So while I heard the noise I tried changing fan speed and changing vent opening from feet to forward to defrost. I also tried the recirc and A/C. No change in noise with any of that. Then I tried hot and cold and didn't initially hear any change. But then my vents started blowing hot air while the switch was on cold. So I went from hot and cold a couple of times and the noise stopped and cold was cold again.

So my thoughts are it's some sort of actuator that shifts from hot to cold air that is somehow self actuating or such?

Any thoughts?