For some reason the ac fan dos not work on 1,2,3 but on 4 it works.
Any idea why it does nto work

 

I believe it's the blower motor resistor that's causing your problem. It's a resistor that lowers the voltage going to the motor in the 1,2 and 3 position so the motor turn accordingly. But in the 4 position the motor gets direct power which causes it to turn at it's full potential. Don't ask me where this resistor is, becasue I don't know. Sorry