Operation CHARM: Car repair manuals for everyone.

Blower Control Module Description

The blower motor control 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 Control Module from HVAC Control Signal out Blower Motor Control Module to Blower
0-5% Duty Off(Short)
6% Duty High
7% - 94% Duty Inverse Veriable 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 control 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.