Air Speed
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.
Afterblow
Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned off. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned on. If the afterblow feature is required due to an odor concern, it must be turned on by the scan tool.
The following conditions must be met for afterblow to operate:
- The A/C compressor operated during the prior key cycle.
- The system voltage is at least 11 volts to start and 10 volts to continue to run.
- The ignition has been in the OFF position for at least 30 minutes.
Once the above conditions have been met the following sequence of events will occur:
- The blower will run for a range of 2 minutes 30 seconds to 4 minutes.
- The recirculation door moves to outside air position.
- The mode valve moves to the floor position.
Auxiliary Blower Motor Control Processor
The auxiliary blower motor control processor is an interface between the auxiliary HVAC control module and the rear blower motor. The auxiliary blower motor control processor monitors supply voltage and ground circuits to the rear blower motor. The auxiliary HVAC control module provides a pulse width modulation (PWM) signal to the control processor in order to command the blower motor speed. The auxiliary blower motor 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 vehicles 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.