Radiator Cooling Fan: Description and Operation

Electric Fan

Electric fan
The power output of the electric fan depends on the version (motorization): 400 W, 600 W, 850 W. The electric fan is arranged behind the cooler. The engine control system activates the electric fan.
A new feature is that the power supply from terminal 30 via a relay comes from the engine control system.
Depending on version, this electric fan cutoff relay is located: behind the glove box or in the luggage compartment next to the battery.

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.







Structure and inner electrical connection
The drive of the electric fan is a brushless motor. The electric fan has its own electronic evaluation unit and its speed is regulated by a pulse-width modulated signal. The pulse duty factor in the normal operating mode (100 Hz) is converted into a speed signal.
- 7% pulse duty factor: Standby mode (electronic evaluation unit is kept awake)
- 11% pulse duty factor: minimum fan speed (33 % of rated speed)
- 93% pulse duty factor: maximum fan speed
- 97% pulse duty factor: command for self-diagnosis of the electronic evaluation unit







Characteristic curve and setpoint values
The permitted operating temperature lies between -20 °C and 120 °C. The static pressure lies between 0 and 0.8 bar.







Observe the following setpoint values for the electric fan:

Size Value
Voltage range 8 to 17 Volts
Nominal speed 2400 rpm
Power 850 or 1000 Watts
Maximum power consumption 70 A ± 3 A
Temperature range -40 to 120 °C

Diagnosis instructions

Failure of the component
If the electric fan fails, the following behavior is to be expected:
- Fault entry in the engine control unit
- Power reduction (if engine overheated)
- Check Control message in the instrument panel
- Damage to thermally critical components in the car front end after stopping the engine (post-heating of the engine)

General notes
The electronic evaluation unit runs an internal fault diagnosis for critical states. If a fault is detected, operation is maintained as far as possible.
If activation by pulse width modulation fails, the electric fan is activated in the emergency mode with a fixed pulse duty factor.

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.