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Ventilation fan

Ventilation fan




The fan is supplied with +30 from fuse 22. The control module regulates the fan control unit, which supplies the fan motor on the ground side. The fan control unit is mounted on the fresh air filter cover.

The fan control unit is supplied with B+ from pin 5 on the ACC unit and power grounded from grounding point G41P. The ground lead is also reference ground from pin 35 on the ACC unit. The fan control unit is controlled by an analogue voltage of 0-5 V from pin 14 on the ACC unit. The fan current increases as the control voltage increases.

The control module regulates the fan current in the following way:


• If the engine is stationary, 5 A is selected.

• When the starter motor engages, 0 A is selected.

• When starting in cold weather, the coolant temperature and outside temperature are determined. The lower the values, the lower the current. For conditions for cold starts, see Cold start in auto .

• Under normal driving conditions it is at its lowest when the current blended-air temperature corresponds with the requested temperature in both zones (none of the zones requires cooling or heating). The current is increased as soon as either of the zones requires cooling or heating.



When defrost or HI has been manually selected, the fan current is set to 18 A. When LO is selected, the fan current is set to MAX. The desired fan speed can also be selected manually on the panel. If fan speed 0 is selected, the A/C will be disengaged and ECON displayed.

The fan speed is shown by a symbol on the ACC unit display.

Adjustment

With the diagnostics tool, the ACC unit can be adjusted to delay fan engagement if there is a risk of mist forming on the inside of the windscreen. This occurs if the engine has been turned off for more than 1 minute and the outside temperature is between 0°C and 15°C, at low solar intensity up to 20 °C.

The delay period can be set to between 0 and 30 s.

Diagnostics

In the event of a short in the control circuit diagnostic trouble code B2425 is set and 20 is shown instead of the right-hand temperature when calibrating.