I completely replaced the O-rings again and still having the same problem. I noticed upon closer inspection that the airflow is not shut off to the dash vents on any mode selected. When I select DEFROST or FLOOR, airflow comes from the selected mode as well as the dash vents. When I select VENT, MAX AC, or NORM AC, airflow comes from the dash vents only. The temperature operates and mixes properly. I see the 2 metallic spherical units behind the EATC moving their armatures in and out when I select the different modes. Is there a door that the armature attaches to that could be jammed or obstructed? I can manually close all the dash vents in order to obtain a sufficient defrost airflow, but that really sucks.
Any other help would be greatly appreciated. If I get this thing fixed, O-rings for everyone!!!!!