I have a 2000 Chevy C2500 and the heat/ac only blows under the dash. I have already replaced the actuator. With the actuator off, I can move the door panel and it will work. What could be causing it? Do I have to replace the heater control panel?
Check actuator electrical circuits, voltage and ground. In the diagram, black wire is chassis ground. Use a testlite connected to battery voltage touch terminal for black wire on wiring harness. If the lite comes on, ground is good. Brown wire is voltage, goes hot with key on. Actually, you could use testlite between black and brown wire terminals, key on, If lites comes on bright, voltage and ground should be ok. The other wire goes to hvac control. Other than a continuity test, not sure how to test that wire? Let us know what you find.