Blower Motor Pulse Width Module (PWM)

The blower motor pulse width module (PWM) contains solid-state circuitry which uses a pulse width voltage signal (at a given duty cycle), from the control head. The PWM then returns and inverse pulse width signal to the blower motor.

The control head pulse width signals are based on the following conditions:

- The blower and mode selections

- The user-set temperature

- The in-vehicle temperature

- The outside air temperature

- The solar (sun load) sensor

If the in-vehicle temperature is much hotter or colder than the user-set temperature, and AUTO mode has been selected, the control module enables the blower motor to run at high speed. As the set temperature approaches, the control module cuts the voltage to the motor and the speed decreases.