Auxiliary Blower Motor Control Processor
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The auxiliary blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the auxiliary blower motor. The auxiliary HVAC control module provides a low side pulse width modulated signal to the auxiliary blower motor control processor over the auxiliary blower motor speed control circuit. As the requested blower speed increases, the auxiliary HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the auxiliary HVAC control module decreases the amount of time that the signal is modulated to ground.