Electric Seat Ventilation, Function - GF91.30-P-0002LF

Model 217, 222

With Code 401 (Climatised front seats)

Model 222

With Code 402 (Rear seat climate control)

Courtesy of MERCEDES-BENZ USA

Function requirements for seat ventilation, general

Circuit 15R ON or circuit 15 ON

The electronic ignition lock control unit sends the status of circuit 15 via the interior CAN to the rear SAM control unit.

Seat ventilation

The seat cushions and backrests can be ventilated in three blower settings using the seat ventilation.

With comfort opening of the vehicle, first the seat cooling (seat ventilation motor drawing) of the driver seat is switched on. If circuit 15R is not switched on after this, the seat ventilation is switched off after t = 5 min.

The seat ventilation setting on the passenger side can be set from the driver side using the left front switch group, seat adjustment.

Model 222.004/057/104/157/163/173

with code 401 (Climatised front seats)

Model 222.004/057/104/157/163/173

with code 402 (Rear seat climate control)

If the pre-entry climate control is activated, the seat ventilation will be activated for the driver seat for max. t = 120 s after unlocking the vehicle. The driver seat is thereby cooled before the journey begins and the entry comfort of the driver is increased.

The seat ventilation switch in the respective seat adjustment switch group is used to switch the seat ventilation on and off and to regulate the ventilation output. The active blower setting is shown using three blue LEDs in the respective seat ventilation switch:

Actuate once: 3 LEDs light up, level 3 of seat ventilation or seat cooling activated, (P = 100 %).
The seat ventilation motors are first actuated in the direction of rotation (seat ventilation motor drawing). After 10 minutes, the direction of rotation changes (seat ventilation).
Press twice: 2 LEDs light up, stage 2 of seat ventilation activated (P = 65 %).
Press three times: 1 LED lights up, stage 1 of seat ventilation activated (P = 35 %).
Press four times: All LEDs off, the seat ventilation is switched off.

In accordance with the status of the seat ventilation, the rear SAM control unit sends status feedback for actuation of the LEDs via the interior CAN to the corresponding front door control unit or rear door control unit (model 222 with code 402 (Rear comfort seats, incl. seat heating and seat ventilation)).

The LEDs in the respective seat ventilation switch are actuated accordingly:

by the left front door control unit via left front door LIN
by the right front door control unit via right front door LIN
From left rear door control unit over the left rear door-LIN (model 222 with code 402 (Rear comfort seats, incl. seat heating and seat ventilation))
From right rear door control unit via right rear door-LIN (model 222 with code 402 (Rear comfort seats, incl. seat heating and seat ventilation))

Actuation of driver seat ventilation:

The left front door control unit reads in the status of the left front seat ventilation switch via the left front door LIN and sends it to the rear SAM control unit via interior CAN. The rear SAM control unit evaluates this and sends the request to switch on the seat ventilation via interior CAN to the driver seat control unit.

The driver seat control unit actuates the following motor groups directly:

Left front seat cushion seat ventilation motors
Left front backrest seat ventilation motors

Actuation of front passenger seat ventilation:

The right front door control unit reads in the status of the right front seat ventilation switch via the right front door LIN and sends this to the rear SAM control unit via interior CAN. The rear SAM control unit evaluates this and sends the request to switch on the seat ventilation via interior CAN to the front passenger seat control unit.

The front passenger seat control unit actuates the following motor groups directly:

Right front seat cushion seat ventilation motors
Right front backrest seat ventilation motors

Actuation of left rear seat ventilation (model 222 With Code 402 (Rear comfort seats, incl. seat heating and seat ventilation)):

The left rear door control unit reads in the status of the left rear seat ventilation switch via the left rear door LIN and sends it via interior CAN to the rear SAM control unit. The rear SAM control unit evaluates this and sends the request to switch on the seat ventilation via interior CAN to the left rear seat control unit.

The left rear seat control unit actuates the following motor groups directly:

Left rear seat cushion ventilation motors
Left rear seat backrest ventilation motors

Actuation of right rear seat ventilation (model 222 With Code 402 (Rear comfort seats, incl. seat heating and seat ventilation)):

The right rear door control unit reads in the status of the right rear seat ventilation switch via the right rear door LIN and sends it via interior CAN to the rear SAM control unit. The rear SAM control unit evaluates this and sends the request to switch on the seat ventilation via interior CAN to the right rear seat control unit.

The right rear seat control unit actuates the following motor groups directly:

Right rear seat cushion ventilation motors
Right rear seat backrest ventilation motors

Reduction of noise level:

In order to reduce the noise level of the seat ventilation motors when the vehicle is stationary, it is shifted down to level 1 if the vehicle speed drops below 6 km/h. From 9 km/h, the originally selected stage is activated. The instrument cluster sends the speed signal via user interface CAN, electronic ignition lock control unit and interior CAN to the rear SAM control unit. The noise level reduction of the seat ventilation motors does not become active until 7 minutes after the respective seat ventilation has been switched on for the first time with the engine running. The reduction of the noise level is not active with comfort opening.

With circuit 50 On (engine start), the power supply is interrupted for t = 20 s. This has no influence on the timer control and the actuation of the LEDs. No undervoltage is detected during startup.

Shutoff criteria:

Switching off in event of error:
In the event of a fault, the seat ventilation is automatically switched off. To this end, the ground power supply is switched off with a protection relay. It is not possible to switch the seat ventilation on again until another ignition cycle has taken place. In the event of a fault, the respective control unit sends a corresponding status message over the interior CAN to the rear SAM control unit.
Shutoff after circuit 15R OFF:
When switching from circuit 15R ON to circuit 15C ON, the timer control runs on for 5 minutes. If the circuit 15R is switched back on within 5 minutes, the seat ventilation is reactivated.
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 seat ventilation is also deactivated if necessary.

With engine start (cold start), the seat ventilation is deactivated for 20 s and with (hot start), e.g. start/stop function, it is deactivated for 3 to 5 s.
Deactivation with undervoltage or overvoltage:
If undervoltage or overvoltage is detected, the respective control unit switches off the seat ventilation motors.

The LEDs in the respective seat ventilation switch initially remain switched on. If the on-board electrical system has been restored to normal voltage levels within 3 minutes, the seat ventilation starts again automatically. However, if the shutoff lasts longer than 3 min, the LEDs in the respective seat ventilation switch are also switched off. If shutoff continues and the seat ventilation is requested again by pressing the respective seat ventilation switch, the LEDs light up for 1.5 s and then go out.
Switch off in event of voltage drop:
If one of the two supply lines of the respective control unit fails, the seat ventilation is switched off.
Shutoff in the event of a hardware defect:
If actuation of the seat ventilation motors by a seat ventilation button is detected without any request pending, the power supply to the seat ventilation is switched off by the respective control unit.
Deactivation in the event of "Time Out":
If the request from the rear SAM control unit to actuate the seat ventilation is discontinued, the seat ventilation is switched off.
Deactivation in the event of short circuit, overload or open circuit (line break):

The respective control unit detects a possible short circuit, overload or a line break in the respective seat ventilation motor and deactivates the power supply.

	Seat ventilation electrical function schematic		PE91.30-P-2053-97SEA
	Overview of system components of comfort heating systems		GF91.30-P-9990LF