2008 with manual HVAC controls. I can vary the temp on both driver and pass sides, but on the pass side it doesn't go to full cold. With the AC on, both controls at full cold, the driver side center dash outlet air is colder than the pass side outlet (also in the center dash). By quite a bit, you can easily feel it with a bare hand.

Clearly both doors/actuators are working. What could be the problem? Any hints appreciated.