when i switch to defrost barely any air flows out of windshield vents, same with the dash vents but they push slightly more air. usually air always flowing from floor vents. when on defrost there is a noise like something might be clogging the airflow. i looked at a few posts and seems like the blend door actuator could be the problem. also sometimes when i switch from floor/ defrost vents to dash vents it will not switch or will take a very long time to change. suggestions?? thanks -danny