Also, another common cause of no low fan is a slight refrigerant leak. This allows a/c operation, but not high enough head pressure to trip the high pressure sw for fan circuit.
Both this and the fan circuit can be verified by jumping the pressure sw at the reciever/drier and see if you have low fan.. if you do, then it is not the wiring/resistor circuit, but the refrigerabt level...The sw is the one with the pig-tail ends