Overview
This document contains the following information:
General
Function requirements
Switching pre-entry climate control on or off using vehicle key.
Switching pre-entry climate control on/off using the button.
Pre-air conditioning for departure time
Function sequence for pre-cooling
Function sequence for pre-warming
General
Depending on requirements, the vehicle interior of the parked vehicle can be pre-heated or pre-cooled before starting a journey.
The pre-entry climate control can be activated/deactivated and the departure time adjusted via the air conditioning menu in the multimedia system or on the web using a browser or an app with a smartphone, tablet or PC.
If a departure time is set there, it can be deactivated in the air conditioning menu.
Function requirements
Circuit 15 off
Auxiliary climate control preset
The high-voltage battery is sufficiently charged.
Switching pre-entry climate control on or off using vehicle key
The climate control functions switch on for pre-heating and pre-cooling for up to five minutes, provided that the function is activated via the air conditioning menu in the multimedia system and the high-voltage battery is sufficiently charged.
It is switched on when the vehicle is unlocked using the button of the transmitter key (A8/1). The specified temperature for pre-entry climate control in the vehicle interior corresponds to the last set temperature on the FRONT heater/air conditioning operating unit switch (S98/1).
During pre-cooling, the following functions are switched on as required:
Automatic air conditioning
Blower
Seat ventilation
During pre-heating, the following functions are started as required:
Automatic air conditioning
Blower
Seat heater
Rear window heater
Switching off is via the stationary heater button (S98/1s12) on the FRONT heater/air conditioning operating unit switch (S98/1).
The following functions remain switched on even after starting the vehicle:
Seat heater
Seat ventilation
Switching pre-entry climate control on/off via button
Requirement:
The ignition is switched off.
The vehicle interior can continue being air-conditioned for up to 50 minutes, e. g. during a break in a journey.
Switching on/off:
Press the stationary heater button upwards or downwards.
The specified temperature for pre-entry climate control corresponds to the last set temperature on the FRONT heater/air conditioning operating unit switch. The red or blue indicator lamp in the stationary heater button goes on or off.
The colors of the indicator lamp in the stationary heater button have the following meanings when the ignition is switched off:
Blue: Cooling is switched on.
Red: Heating is switched on.
Yellow: Departure time is preselected.
Pre-air conditioning for departure time
The departure time can be set, selected and activated using a web-based app or the air conditioning menu in the multimedia system.
With web-based programming, the HERMES control unit (N112/9) receives the requests and sends them to the electronic ignition lock (EZS) control unit (N73) and to the powertrain control unit (N127). The powertrain control unit then sends the activated departure time to the automatic air conditioning (AAC) control unit (N154), which stores this.
The automatic air conditioning (AAC) control unit now calculates the required starting time for the pre-entry climate control and sends this to the powertrain control unit. Once the starting time is reached, the powertrain control unit sends the request for pre-entry climate control to the automatic air conditioning (AAC) control unit.
The automatic air conditioning (AAC) control unit also continuously transmits information about the operating status of the pre-entry climate control to the HERMES control unit.
The information stored there can be retrieved using the smart phone, tablet or PC, for example.
If the vehicle is connected to power supply equipment, the charging of the high-voltage battery takes priority up to a specified minimum charge level. Under the following conditions, the runtime of the pre-entry climate control can be reduced:
The vehicle is not connected to power supply equipment.
The high-voltage battery is not fully charged.
Active pre-entry climate control can reduce the state of charge of the high-voltage battery even if the charging cable connector is plugged in.
The pre-entry climate control is not started if all driver compartment windows and doors are not closed, the hood is open or the ignition is ON.
It is also interrupted if a driver compartment door is opened during ongoing pre-entry climate control and left open for longer than one minute. The opening of a window when pre-entry climate control is activated terminates pre-entry climate control immediately.
To operate pre-entry climate control for the departure time, the automatic air conditioning (AAC) control unit assesses the following information:
Interior temperature
Specified temperature at automatic air conditioning (AAC) control unit
Ambient temperature
Solar radiation
If the interior temperature is above the selected specified temperature, the vehicle is cooled. If the interior temperature is below the selected specified temperature, the vehicle is heated.
The vehicle interior is cooled or heated until the desired temperature in relation to the set departure time has been reached. To do this, the auxiliary climate control is activated max. 50 minutes in advance. If the departure is delayed, the climate control for the vehicle interior is continued for an additional 10 minutes.
The pre-entry climate control is ended once the vehicle is started or once 10 minutes have passed since the selected departure time.
Function sequence for pre-cooling
If cooling is required, the automatic air conditioning function is started.
The automatic air conditioning (AAC) control unit actuates the following components:
Electric refrigerant compressor (A9/6)
Fresh air/ram air/air recirculation flap actuator motor (M2/13)
Left air mixing flap actuator motor (M2/6)
Right air mixing flap actuator motor (M2/7)
Detailed information on the individual measures is available in the "Electric vehicle climate control function" description.
Function sequence for pre-warming
If heating is required, the following functions are started as needed:
Heat boosting through high voltage PTC heater control unit
Seat heater
Rear window heater
Heat boosting through high voltage PTC heater control unit
The automatic air conditioning (AAC) control unit actuates the high-voltage PTC heater control unit (N33/7).
The high-voltage PTC heater control unit heats the coolant. The coolant temperature in the heating circuit is read in by the automatic air conditioning (AAC) control unit from temperature sensors.
When the coolant has reached a temperature of 35 °C, the automatic air conditioning (AAC) control unit actuates the following component parts:
Electric auxiliary water pump (M13/15)
Condensation prevention switchover valve (Y16/10)
Fresh air/ram air/air recirculation flap actuator motor (M2/13)
Left air mixing flap actuator motor (M2/6)
Right air mixing flap actuator motor (M2/7)
The circulation pump delivers coolant from the high-voltage PTC heater to the heater core and thus enables heating of the vehicle interior.
Seat heater
The automatic air conditioning (AAC) control unit sends the request to switch on the seat heating to the signal acquisition and actuation module (SAM) control unit (N10/1).
The signal acquisition and actuation module (SAM) control unit sends the seat heating request to the seat heater/ventilation control unit (N32/2), which directly actuates the driver and front passenger seat heater pads.
The seat heating is actuated shortly before the departure time and remains activated after the vehicle has been started.
Rear window heater
The automatic air conditioning (AAC) control unit sends the request to switch on the rear window heater to the signal acquisition and actuation module (SAM) control unit, which then actuates the rear window heater (R1).