Where are the heater & A/C (HVAC) temperature and air delivery mode door actuators? on 2003 Cadillac DeVille

When I try to get the air to come out of the vents on the front of the dash, the door or actuator just clicks. The air blows out of the defroster and floor vents all the time. Where is the actuator and the vent door?

Asked by for the 2003 Cadillac DeVille
from my knowledge the door actuator is located behind the dash no way to get to it other than removing the complete dashboard..could be costly!!!!!
I have an identical problem and would like to hear from someone who knows what needs to be done to fix this condition. Thanks!