Functional description
The electric fan is controlled by the engine control unit via a pulse-width-modulated signal (evaluation by electronic circuitry in the fan). The engine control unit controls the various radiator fan speeds by means of a pulse-width modulated signal (between 7% and 93%). Pulse duty factors less than 7% and greater than 93% do not trigger activation but rather they are used for fault recognition purposes. The speed of the radiator fan is dependent on the coolant temperature at the coolant outlet (radiator) and the pressure in the air conditioning system. When the cars driving speed increases, the speed of the radiator fan decreases. For the after-run of the electric fan, the engine control system lowers the frequency to 10 Hz. The pulse duty factor is used to select the time (maximum 11 minutes) and fan speed.
| Item | Explanation |
|---|---|
| 1 | Drive for electric fan |
| 2 | 4-pin plug connection |
| 3 | Fan cowl |