topdogracing 1/6/2013you probaly have a vacum leak under the hood or a bad vacum line the vents are vacum controlled
CVO 1/6/2013The Mode Door Actuator controls the direction of airflow. It selects which way air flows through the different ducts. If your climate control system has lost the ability to control which vents the air comes out of, the MDA has probably failed. Both the ATC and MTC systems use this device.
Both failures can be seen by the climate control system's integrated diagnostics system.
See this http://www.autozone.com/.../...rGuideContent.jsp