Front Blower Motor Control Processor
The front blower motor control processor is an interface between front HVAC control module and front blower motor. The front blower control processor regulates supply voltage and ground circuits to front blower motor. The front HVAC control module provides a blower speed signal to the control processor in order to command the desired blower motor speed. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.
The blower motor forces air to circulate within the vehicle's interior. The vehicle operator determines the blower motors speed by placing the blower motor switch in a desired speed position or by selecting automatic operation. In manual operation, once a blower speed is selected, the blower speed remains constant, until a new speed is selected. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature.
As the requested blower speed increases, the following conditions occur:
- The HVAC control module increases the amount of time that the blower motor speed control circuit is modulated to ground.
- The voltage and duty cycle, measured between the blower motor speed control circuit and ground, decrease.
As the requested blower speed decreases, the following conditions occur:
- The HVAC control module decreases the amount of time that the blower motor speed control circuit is modulated to ground.
- The voltage and duty cycle, measured between the blower motor speed control circuit and ground, increase.
If an OnStar® call is initiated while the blower is in the high speed position the blower speed will be lowered to reduce background noise.