I would say the top lever is obviously for the fan, the next lever is to control the mix of hot air to fresh cold air to achieve your desired temp, and the last lever switches from heater outlet to defrost outlet. I bought new cables from firebirdcentral.com and they did not match the origional lengths at all. They were much longer. The fan and heater/defrost work great, but the cold/hot control seems to be backwards. It is baffeling because I know all cables come out of the control on the same side, and I know that the cold/hot control behind the glove box has a mount to secure the cable on the left side, and attach to the shaft connected to the flapper. There is another shaft at this location that would let the lever operate in the opposite direction, but there is no way to secure the cable.