Ventilation fan
| Ventilation fan |
The fan is supplied with power from +30 from fuse C. The ACC unit controls a fan control that supplies the fan motor on the ground side. The fan control is located on the driver side of the climate control unit housing and is cooled by the airstream in the evaporator casing.
The fan control is supplied with B+ from the ACC-unit pin 5 and is grounded from grounding point G34P (LHD) and G33P (RHD). The ground lead also has a reference ground from the ACC-unit pin 1. The fan control is controlled with an analogue current of 0-5 V from the ACC unit pin 14. The fan power increases with the control current.
The fan speed is affected as follows in the AUTO position:
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Increased difference between selected temperature and cabin temperature results in increased fan speed.
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Outside temperature under +5˚C or above +20˚C increases fan speed.
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Increased solar intensity with outside temperatures over +15˚C increases fan speed.
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Desired fan speed can also be selected manually on the ACC unit. The selection can be made in 10 steps of approximately 2 A each. If the button is held down for longer than one second, the fan speed increases or decreases automatically. The fan speed is shown on the ACC display.
| Adjusting |
The diagnostic tool can be used to adjust the ACC unit to delay fan engagement if there is a risk of misting on the inside of the windscreen. This occurs if the engine has been switched off for more than 1 minutes and the outside temperature is between 0˚C and 15˚C, with low solar intensity up to 20˚C.
The time delay is adjustable between 0 and 30 seconds.
| Diagnosis |
In case of a short circuit in the control circuit, diagnostic trouble code B2425 is generated, and 20 is shown instead of the temperature at calibration.
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