The blower motor controller module contains solid state circuitry. At a given duty cycle, the circuitry utilizes a pulse width voltage signal from the control head. The circuitry returns an inverse pulse width signal to the blower motor.
Signal to Blower Motor Controller Module from HVAC Controller  | Signal out of Blower Motor Controller Module to Blower  | 
|---|---|
0 - 5% Duty  | Off (Short)  | 
6% Duty  | High  | 
7% - 94% Duty  | Inverse Variable Output  | 
95% Duty  | Low  | 
96% - 100% Duty  | Off  | 
The control head pulse width signal is based on the following conditions:
| • | The temperature set by the user | 
| • | The outside air temperature | 
| • | The in-vehicle temperature | 
| • | The input from the solar sensor | 
For example, the blower motor control module will adjust the blower accordingly when the following conditions exist:
| • | The temperature inside of the vehicle is much colder or hotter than the temperature that the user sets. | 
| • | The user selects the AUTO button. | 
The blower motor controller module will change the blower from a high speed to a low speed as the temperature inside the vehicle becomes closer to the set temperature.