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 Automatic Temperature Control (ATC) programming. The ATC blower motor control system uses a Pulse Width Modulation (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.