I leave mine on dash vents all summer, and defrost almost all winter. If the ac could only be turned off while in the defrost position, then there really would be no need to constantly move those doors.
Has anyone looked at the wiring diagram? I wonder if it is possible to weaken those motors (by adding a resistor?) so they don't put so much torque on the flimsy plastic door.
Maybe DC should reflash the motor controllers to get them to put out less torque so they don't break those doors. And also to allow us to turn off ac with defrost on?
Dr Z, are you reading this?