AIRSCARF System, Function - GF91.30-P-0008LF

Model 217.4 

with code 403 (Heating in head area) 

Courtesy of MERCEDES-BENZ USA

Function requirements, general 

• Circuit 15R ON
• Interior temperature less than 40°C

The electronic ignition lock control unit sends the status of circuit 15 over the interior CAN, rear SAM control unit and the heater LIN to the AIRSCARF control unit.

The climate control control unit sends the interior temperature value over the interior CAN, rear SAM control unit and the heater LIN to the AIRSCARF control unit. If a valid interior temperature value is not available, the outside temperature is evaluated as a substitute value.

AIRSCARF 

AIRSCARF ventilates the area around the driver or front passenger's neck with air heated at three heating levels. The warm air comes out of an opening below the respective head restraint.

Controlling of the AIRSCARF function takes place by means of the AIRSCARF control unit depending on the following variables:

• Selected heating level
• Outside temperature
• Soft top status
• Vehicle speed

AIRSCARF is operated by using the AIRSCARF switch in the relevant SSE (initial state, AIRSCARF deactivated, all LEDs off):

• Press once: 3 LED light up, stage 3 activated (P = 100 %)
• Press twice: 2 LEDs light up, stage 2 activated (P = 65 %)
• Press three times: 1 LED lights up, stage 1 activated (P = 35 %)
• Press four times: All LEDs off, AIRSCARF switched off

The appropriate front door control unit reads in the status of the AIRSCARF switch via the door LIN. Then it transmits this status to the AIRSCARF control unit via the interior CAN, rear SAM control unit and heater LIN.

For vehicles as of model year 2018, AIRSCARF can also be operated using the voice control system. The head unit transmits the relevant requests to the AIRSCARF control unit via the user interface CAN, electronic ignition lock control unit, interior CAN, rear SAM control unit and heater LIN.

The AIRSCARF control unit actuates the following components according to the request:

• Left front seat AIRSCARF fan motor
• Right front seat AIRSCARF fan motor
• Left front seat AIRSCARF heating element
• Right front seat AIRSCARF heating element

The AIRSCARF fan motors are switched on after a 7 s delay. This prevents any cold air from flowing out immediately after activating the AIRSCARF function. For secure start-up of the AIRSCARF fan motors, these are actuated independently of the selected heating level for 0.5 s with the maximum control voltage. During switch-off, the AIRSCARF fan motors run on at the lowest stage for 5 s to protect the AIRSCARF heating elements from overheating.

Controlling of the AIRSCARF fan motors and the AIRSCARF heating element takes place depending on the selected heating level. The rotational speed of the AIRSCARF fan motors is also controlled for an opened soft top depending on the vehicle speed and the outside temperature.

For this, the AIRSCARF control unit receives the following information:

• Outside temperature:

  The front SAM control unit sends the outside temperature value over the interior CAN, rear SAM control unit and the heater LIN to the AIRSCARF control unit.

• Vehicle speed:

  The instrument cluster sends the displayed vehicle speed over the user interface CAN, electronic ignition lock control unit, the interior CAN, rear SAM control unit and the heater LIN to the AIRSCARF control unit.

• Soft top status:

  The rear control unit sends the soft top status over the interior CAN, rear SAM control unit and the heater LIN to the AIRSCARF control unit.

Function feedback: 

The AIRSCARF control unit sends the corresponding status via the heater LIN, rear SAM control unit, interior CAN, front door control unit and the door LIN to the respective switch group, seat adjustment for feedback on the function. The respective switch group, seat adjustment actuates the corresponding LEDs in the AIRSCARF switch directly.

Shutoff criteria: 

When one of the following situations occurs, the AIRSCARF function is switched off automatically:

• Shutoff in the event of a hardware defect: 

  If the AIRSCARF control unit reports active actuation of the AIRSCARF heating elements although there is no request, then power supply to AIRSCARF heating elements is shut off.

• Shutoff in the event of overtemperature of the printed circuit board: 
  • At a printed circuit board temperature of more than 90°C, heating level 3 can no longer be activated.
  • At a printed circuit board temperature of more than 100°C, heating level 3 and heating level 2 can no longer be activated.
  • At a printed circuit board temperature of more than 110°C, the AIRSCARF function is switched off.

  When a printed circuit board temperature of more than 110°C is reached, a fault message is stored in the fault memory. Manually switching back on requires the affected components to cool down to a value of 2°C below the corresponding temperature threshold.

• Shutoff in the event of an error (short circuit, overload or open circuit (line break)): 

  The AIRSCARF control unit constantly monitors the functional capability of the corresponding components, and sends the status to the rear SAM control unit. Among others, the following are monitored:

  • Absent signals
  • Short circuit
  • Open line

  If there is a defect, power supply to component parts is deactivated and an error is stored in the fault memory of the rear SAM control unit.

• Shutoff during engine starting procedure: 

  During the starting procedure of the engine, the AIRSCARF heating elements and the AIRSCARF fan motors are switched off. The LEDs in the AIRSCARF button remain switched on for the selected heater stage.

• Switching off by energy management: 

  In order to prevent the battery from discharging in all driving cycle phases, the state of charge is continuously evaluated. Depending on the situation, the AIRSCARF function is also deactivated.

  If the AIRSCARF function is deactivated, the LEDs initially remain switched on. If the on-board electrical system reaches its on-board electrical system voltage again within 3 min, then the AIRSCARF function also starts automatically. If the shutoff takes longer than 3 minutes, the LEDs are also switched off. If the shutoff continues and the function is requested again, the LEDs illuminate for 1.5 seconds and then they go off.

• Shutoff after circuit 15R OFF: 

At circuit 15R OFF and circuit 15C ON, the timer control runs on for 5 minutes. If circuit 15R is switched on again, the AIRSCARF function is also switched on again.

	Electrical function schematic for AIRSCARF		PE91.30-P-2051-97SEA
	Overview of system components of comfort heating systems		GF91.30-P-9990LF