Thanks. That makes sense. Would the AC servo continue to function when the AC is turned off? I tend to use the defrost when it is raining and it is usually cool air even if the AC is not on.
'which servo'.... does this mean there is more than one?
OK, I understand how each of the vents would have a door with a switch to change positions, and a motor to operate the switches...
This helps greatly and I will live with the sound for a while. I may play around to see if changing AC settings makes any difference. Thank you very much.