2003 Suburban with automatic climate control. When the vent position is set to upper vents only, the blend door actuator makes noise. If I watch the actuator I can see it still trying to move a little and I see the plastic flex. The actuator seems to work fine and move the blend door through the full range of motion without any issues. Any ideas what could be causing it to make noise and keep trying to move? It's almost like it doesn't detect that it is at the end of the range of motion or something.

 

Most likely the large gear inside the actuator has cracked and skipped a spline or 2 on its shaft. Time for a new actuator.

 

OK that makes sense. I was hoping maybe it was something simple and wouldn't require replacement. When I have more time I'll take it out and see if I can get a good look at it. Thanks!