Blower Motor: Description and Operation

Ventilation Fan
The fan is powered directly with a + 54 supply from fuse 12.

On the ground side the fan is connected to a fan control which receives a control voltage of 0-5 V from the ACC control module.

The fan control also receives a special voltage supply from the ACC control module.

The ACC control module receives feedback from the ground side of the fan motor, which gives it information on the actual voltage across the fan motor. The feedback voltage increases in relation to ground as fan speed decreases.

Fan speed is affected in the AUTO mode of operation as follows:
1. As the difference between selected temperature and cabin temperature increases, fan speed also increases.
2. Outside temperatures below +5 °C or above +20°C result in higher fan speed.
3. Increased solar intensity at outside temperatures above +15 °C results in higher fan speed.

The desired fan speed can also be selected manually on the ACC panel. It can be set in ten steps of about 2 A each. If the button is depressed for more than one second, fan speed will increase or decrease automatically. Fan speed is shown on the ACC panel display.