Air Speed

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

The blower control switch is part of the HVAC control. The selected value of the blower switch position is sent to the BCM via serial data.

The blower motor speed is controlled by increasing or decreasing the voltage drop on the ground side of the blower motor speed control circuit. The BCM provides a low side pulse width modulation (PWM) signal to the blower motor via the blower motor speed control circuit. As the requested blower speed increases, the BCM increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the BCM decreases the amount of time that the signal is modulated to ground. The blower motor internal circuitry processes the PWM signal to drive the motor at the requested speed.

Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned OFF. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned ON. If the afterblow feature is desired due to an odor concern, it must be enabled using the scan tool Afterblow Configuration function.