Function

Function

Air conditioning
See: Air conditioning Air Conditioning

Air distribution system
See: Air distribution system Air Distribution System

Blower fan




The blower fan provides the airflow through the vehicle.
The blower fan must be operating before the climate control system can be engaged.

Filter




The particle filter cleans the air of particles such as dust and pollen, which would otherwise pass through the air intake into the passenger compartment.
The multi-filter has the same function as the particle filter, but also neutralizes unpleasant smells and keeps the air as free from gases as possible. In vehicles that have the multi-filter, known as the air quality system (AQS), there is also an outside air sensor that ensures that the recirculation closes in the event that the content of gases in the outside air increases. This increases the service life of the multi-filter.

Heat exchanger




The task of the heat exchanger is to provide heat for the passenger compartment.

PTC element (Positive Temperature Coefficient)




The electric PTC element speeds up the supply of heat to the passenger compartment when cold-starting. It is automatically connected when starting in cold conditions.

Additional heater/Parking heater




The additional heater/parking heater produces heat by burning gasoline or diesel. The heat is distributed via the engine cooling system to the heat exchanger and on out into passenger compartment.
When the engine is running, the additional heater can provide extra heat to the passenger compartment in the event that the engine is unable to provide sufficient heat. When the engine is not running, the parking heater can heat the passenger compartment (and the engine). This function can be started directly or using a timer.
In order to start the additional heater, all the following conditions must be satisfied:
- The engine speed (RPM) is higher than 500 RPM. (The additional heater will not operate while the engine is being started - minimizing the risk of the battery becoming too weak.)
- The ambient temperature is below 5 °C
- The driver has selected a temperature for the passenger compartment that demands additional heat and the blower fan is operating
- The fuel level is above 5 liters.
The additional heater is switched off when one or more of the following conditions are satisfied:
- The engine speed (RPM) is lower than 400 RPM
- The ambient temperature is above 11 °C
- The driver has selected a temperature for the passenger compartment that does not demand additional heat and the blower fan is switched off
- The fuel level is below 3 liters.
The parking heater is controlled via the turn signal lamp stalk. The information appears in the driver information module (DIM). When the engine is started, after the parking heater has been switched on, the parking heater will remain in operation for a further 2 minutes. During these 2 minutes, the heater detects whether all the conditions have been satisfied in order for it to remain switched on. This is to avoid stopping and restarting the heater.
For further information about the additional heater/parking heater, see Design and Function, combustion preheater module (CPM).