I’m having some trouble with my 1997 GMC Suburban k2500 with a 496 stroker. The upper A/C vents (that blow air directly on you) will not blow any air out. I have replaced the A/C controls, and the blend door actuator. While I had the actuator off, I moved the blend door mechanism with my fingers to the upper vent position and nothing came out. The actuator is turning as it should. Blower motor is working strong, and the lower vents as well as defroster both work. The A/C itself is not charged and does not work at this time. I don’t see how this could be related to my issue though. I would appreciate any suggestions.