Theory Of Operation

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.