I have a 68 442 without A/C and I just replaced the blower motor because the old one ran very slow. The new run higher but only on medium and high speeds but not at low speed. Fusicks sells a 64-70 heater blower resistor for models without A/C But it has 4 prongs. My heater blower resistor has 3 prongs, do I have the incorrect resistor? Am I missing a wire?, is this why it only works on medium and high but not on slow?

 

Heater-only cars used a resistor with three terminals. The wires should be yellow, blue, and black with orange stripe. The latter should have two wires on the terminal in the plug, one that goes to the fan switch and one that goes to the fan motor. In high the switch connects directly to the motor, bypassing the resistor.