I just bought and installed a new Hunter fan to replace an old fan. I also bought a compatible 3-wire wall switch. The fan is up and works. Upon reading the directions for the wall switch, it says "if one wall switch currently supplies power to both fan and light, additional wiring will be required." I think this is my situation because upon opening my existing single wall switch, there are only one red and 2 black wires coming from the wall. I am pretty sure the red is the hot, but what about the black wires? The existing switch doesn't help either. There are no labels on the switch to help me identify the black wires. What do I do?

Are there any other wires in the switch box. Are the red and two black wires in the same cable? Normally they woud be black, whit e and red and in the same cable if they are only wires in the box. Look again.

How was the original fan controlled?

Also, how did you hook up the new fan at the ceiling?