The blower motor is a variable speed motor. The motor operates at a higher rate when voltage is increased to the maximum level.

The blower motor resistors reduce the voltage supplied from the A/C FAN fuse (LH IP Accessory Wiring Junction Block) when the blower control is set at low and medium speeds (speeds 1-4). The blower motor relay is energized when the Blower Motor Control is set to the High position. This removes the blower motor resistors from the circuit and battery voltage is then applied directly from the HVAC BLO fuse (RH IP Accessory Wiring Junction Block) to the blower motor though the relay switch contacts. The blower motor then runs at high speed.