I know this question was asked over a year ago, but for the sake of possibly helping someone else out in the future, the procedure that was mentioned about holding the defrost/power button for 5 seconds and then pressing the power button is some sort of AC reset/recalibration. When you do that, you will hear the small motors (blend door actuators) reset and run through a full sweep. It will then move the air across all vents in order and once done, it usually re-aligns the blend door actuator in question.
This is a temp fix though. It will get you through that one issue, but will come back. Eventually you will want to replace the affected actuator. The passenger side one is behind the glove box, the driver side one is up under the dash/center stack. Each part is roughly $50 if applicable.