Heating And Ventilation: Blower

The blower is installed in the air inlet duct, below the cabin air filter, and consists of an open hub, centrifugal fan powered by an electric motor. Operation of the blower is controlled by the automatic temperature control (ATC) module, using the blower relay in the battery junction box (BJB) and the blower control module. The blower control module is installed in the air inlet duct downstream of the blower, where any heat generated during operation is dissipated by the air flow. A wiring harness on the air inlet duct connects the recirculation door motor, blower and blower control module to the vehicle wiring.

When the blower is required, the automatic temperature control (ATC) module energizes the coil of the blower relay. The energized blower relay supplies battery power to the blower motor, which is connected to ground through the blower control module. The speed of the blower is controlled by the blower control module, which regulates the blower motor voltage in response to a pulse width modulation (PWM) signal from the automatic temperature control (ATC) module. To vary the blower motor voltage the automatic temperature control (ATC) module varies the duty cycle of the pulse width modulation (PWM) signal.

When the blower is in the automatic mode the automatic temperature control (ATC) module determines the blower speed required from the comfort algorithms. When the blower is in the manual mode, the automatic temperature control (ATC) module operates the blower at one of seven fixed speeds as selected on the control panel. Refer to Control Components information.