Heating system — general information (BMW 5 Series E39)

Fresh air is sucked in through the intake grille of the fine filter housing, located under the windshield, and is supplied by the fan into the car's interior. The air passes through the heater housing and is directed to the appropriate air nozzles using various valves controlled by Bowden cables. If the heating system is turned on (warm), then the cold air is directed through the heat exchanger. The heat exchanger is located in the heater housing and is heated by the hot liquid of the engine cooling system. The flowing air is heated by the hot plastics of the heat exchanger and is then supplied to the interior of the car. The efficiency of the heating is regulated from the liquid circuit. This means that the temperature is determined by the flow rate of the liquid through the heat exchanger. The flow rate, in turn, is regulated by two electromagnetic valves built into the coolant circulation system.

The air temperature for the left and right parts of the passenger compartment can be set using rotary controls. In accordance with the position of the controls and the temperature in the passenger compartment, the electronic unit located in the control unit of the heating system regulates the opening time of the heating valves. The air temperature sensors in the passenger compartment are located on the rear side of the heater housing. Thanks to electronic control, the temperature in the passenger compartment is maintained almost constant regardless of the speed of the car and the ambient temperature.



To increase the performance of the heating system, a fan with stepless speed control built into the heater is used.