First off, I did a vacuum actuator test. I could see all the actuators work i.e. the max a/c, the blend door, and actual heat/air control when I took the door off to access the heater core. It seems that the heater core has been replaced quite recently. But when I change the air flow from the vents to floor/defrost, I can see the blend door just push its way into the heat/air control door instead of diverting flow like it should. I can take the blend door and move it by hand, but it only works to pull the door to divert air to the vents. I can close the blend door by hand and it will divert flow back to the floor. This leads me to suspect that the blend door hinge is toast. Anybody know what kind of job that will be? Removal of the dash pad and duct work to get into it to replace the door?