AC selection give cold air but blows out of all vents, including heater and defroster vents. I adjust controller through options (except defroster,) air flow results are the same. However, if I select only defroster, cold air come out of defroster vents only. Several Google searches indicate that there are three actuators. But, searches yield misleading responses to the specific actuator that I need to test or replace. I believe that it is the one nearest gas peddle. One search result stated that I needed to be careful when removing or replacing it since I might get gears out of index order. If so, how do I create a starting point? Or should I be examining the other actuators?

 

I've replace a couple of GM actuators. Never had a problem with adjustments. It was plug and play both times.

 

Actuators are moving. I examined them while moving dash (control box) selector. I suspect something is worn internally or stripped inside vent box. I get cold air but I cannot get it to specifically and only blow on my face. It comes out all vents, including floor and defr. Yet, if I select def. Air comes out only defr. vent. Weird. I would have to be double jointed to remove and inspect floor box. I am too fat and old to work upside down and on my back for hours.