If this is a GT there is a power resistor mounted on the heater blower box. If the connections there are bad it won't work on low. Also if the motor bearings are full of old grease then the motor may have enough torque to turn it when at full voltage but when dropped to the lower voltage for low speed it may not have the torque and therefore it will not work. Check the resistor first, follow the wires up under the dash.Hello Again. My heater blower works on full power, but on half way, motor stays still. Is this the switch, or something else (before I take half the car apart to get to it all).