Electric seat ventilation, function

P91.30-2190-76

N25/7 HS [SIH] and seat ventilation control unit

N72/1 Upper control panel control unit

N73 EIS [EZS] control unit

N72/1s13 Left front seat ventilation switch

N72/1s14 Right front seat ventilation switch

Function

Three levels of active seat cushion and backrest ventilation are possible using the seat ventilation integrated in the left and right seats.

The logic for controlling the seat ventilation at three levels is implemented in the HS [SIH] and seat ventilation control unit.

The front left and right seat ventilation switches are in the form of buttons. The operation of these buttons is read in by the upper control panel control unit and relayed to the HS [SIH] and seat ventilation control unit via the interior CAN.

The HS [SIH] and seat ventilation control unit outputs a control voltage to an external blower regulator depending on the current setting. Depending on this control voltage, this blower regulator controls the supply voltage to the left front seat cushion ventilation motor group (M18/9) and the

left front seat backrest ventilation motor group (M18/10) and the supply voltage of the right front seat cushion ventilation motor group (M18/11) and the right front seat backrest ventilation motor group (M18/12).

The seat ventilation function is indicated by a number of blue LED's in the left front or right front seat ventilation switch. One to three LED's are energized depending on the required ventilation level.

For a reliable fan motor startup, these are actuated for a period of 0.5 sec. in ventilation level 3 when the ventilation is switched on, irrespective of the following output level.

The operation and function indicators of the seat ventilation are summarized in the table below.