The clicking noise is the gear teeth slipping on the motor gear,..teeth strip and there is the noise. Ford has a bad design all these years with these motors. When the ignition is turned on, the motors try to sync. While doing this if the blend door temp control is all the way to the stops either hot or cold, the motor forces the door in the direction of the temp control. What seems to help prevent the issues is to not turn the temp control all the way. On the older fords just run the control at the edge of the blue or red range. In the newer models like my 16, I just back the temp knob back off the stop one click. Maybe this helps , maybe it won't, your milage may vary