Functional description

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2017 BMW X3, 2016 BMW X3, 2015 BMW X3, 2014 BMW X3, and 2013 BMW X3. However, it is still accessible from the selected car via links, so may be relevant.

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.

Fig 1: Identifying Fan And Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Drive for electric fan
2	4-pin plug connection
3	Fan cowl