[dajabi]

First off...Thanks BigDaddyHD for the post. It helped me fix my 2000 Z71 4x4 heater control. My main reason for replying is directed to Plowboy77. I too wanted to watch the actuator in action. I did and proceeded to jam it in the far HOT position and had to take it apart to un-jam.
Truth be told, when actually installed and the control is turned to the max HOT position, the heat damper door inside the heater assembly must have a shorter range of travel than the actuator unit will move, therefore it gets tightly closed and stalls out before getting bound up. Hope this helps you.
Dajabi