Low Blower Speed
WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.
When the Low blower (1) speed is selected, the HVAC control assembly applies voltage to the blower motor resistor assembly through the low blower motor control circuit. Low blower speed voltage will bypass the blower mode switch completely. Voltage is divided between 3 series resistors in the blower motor resistor assembly, to the blower motor relay on the blower motor supply voltage circuit, and the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage and ground circuits. The ground circuit provides a ground path for the blower motor.