Blower Motor Resistor
WARNING: This page is about a different car, the 2018 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.
The blower motor resistor consists of 3 resistance elements mounted on a resistor board wired in series on the ground side of the blower motor. Depending on the heater blower motor switch position, series resistors are added or bypassed in the blower motor resistor to decrease or increase blower motor speed. To provide the 4 blower motor speeds, the HVAC control module grounds 1 of the 4 circuits:
- for low speed, all 3 resistors are used
- for medium-low speed, resistors 1 and 2 are used
- for medium-high speed, resistor 1 is used
- for high speed, the blower motor is provided a path directly to ground and the blower motor resistors are not used