My original problem was that the blower switch only operated on High speed. I installed a new resistor and repaired it, thanks to some very knowledgable people on this forum. However, when I finished that job the vent selector now is not changing vents for me. I just get airflow out of the defroster. Previously, when changing vents, I would hear a light thumping sound. Like a vent door closing. Any help is appreciated.