Theory Of Operation
WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
A Blower Motor Power Module allows the microprocessor-based HVAC Module to calculate and provide infinitely variable blower motor speeds based upon either manual blower switch input or the ATC programming. The ATC blower motor control system uses a Pulse Width Modulated (PWM) circuit strategy. PWM voltage is applied to a comparator circuit which compares the PWM signal voltage to the blower motor feedback voltage. The resulting output drives the power module circuitry, which provides a linear output voltage to change or maintain the desired blower speed.