I have a 1990 chrysler lebaron v6 with auto and a/c. My air vent controls don't operate, so the air inside the car is directed to the floor vents only. The fan works and so does the heat. It's just that the air can't be directed to the upper vents. Air does come out slightly out of the windshield vents as well. Is it the actuator or could a vacuum hose have come loose?
Near the brake booster, you will find a very thin black and a very thin grey vacuum hose going into the firewall, one is vacuum going into your controller and the other one is to your heater control valve. They are brittle after a few years and crack easily. If they aren't broken, you have to see if you get a vacuum signal to the diaphram. It's not a cakewalk, but you can do it at home. By the way, the heater control valve shuts off the heat, so if there is no vacuum to it the heater would still work.