Control of the electric auxiliary heater
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.
On vehicles with diesel engines and without independent heating, the heat exchanger for the heating system is heated additionally with an electric auxiliary heater based on the PTC principle. The electric auxiliary heaters one of the consumer units that need a relatively high amount of power (up to 1300 W) and it is thus regulated by power management. Furthermore, two other electric auxiliary heaters (300 W each) are used in the rear on vehicles with rear air conditioning. These high electrical loads are regulated as follows:
- The IHKA control unit controls the electric auxiliary heater (via LIN bus) and the FKA control unit controls both electric auxiliary heaters in the rear passenger compartment (with a pulse-width modulated signal).
- The power management in the DDE regulates the maximum electrical power output of the electric auxiliary heater (signal in a CAN signal).
The maximum power output of the electric auxiliary heater depends on the utilization of the alternator.
- The electric auxiliary heater regulates the heater output of the heating register depending on the specifications of the power management.