Recently bought a 2007 Honda Accord SE. The A/C, heat and defrost work great but only three vents have air flow. The driver side vent has nothing coming out. I did the self diagnostic and there were no codes. Is it possible there is a problem with the blender door actuator or possibly the thumb dial is broken? Is it simple to take out the vent to check to see if the dial is broken?

 

You can check if it's the blend door by changing the settings and seeing if the actuator moves.