Seat Ventilation

Seat Ventilation

The seat ventilation feature of the comfort seat allows the front seat occupants to cool the seat cushion and backrest.







The following components are required for the seat ventilation function:

- Switch block, auxiliary functions, driver and passenger
- BZM
- Car Access System (CAS)
- Seat module, driver and passenger (SMFA/SMBF)
- 9 smart ventilation fans per seat

The auxiliary function switch block contains the control button and 3 LEDs for displaying the ventilation stage.

The signals for operating the seat ventilation are transmitted over the buses.

Signal path: Switch block 14-pin ribbon cable BZM K-CAN S CAS K-CAN P SMFA or SMBF.




The relevant seat module activates and monitors the fans. The fans:

- Are activated by the seat modules supplying voltage.
- Can be activated separately for back rest and seat cushion.
- Can be operated in 2 speed stages (high and low) via a control/diagnosis line.
- Iridicate possible jamming for diagnosis over the control/diagnosis line.

Fault code only identifies whether the defective is in the backrest or the cushion it does not identify individual fan motors.

Operation

The seat ventilation can be turned on from KL 15 "on" and the engine running.

Seat ventilation has 3 stages but only two fan speeds:

- Stage 3: High speed backrest, high speed cushion (seat bottom)
- Stage 2: low speed backrest, high speed cushion
- Stage 1: low speed backrest, low speed cushion

Stage 3 is activated when the button is pressed for the first time. Each subsequent pressing of the button selects the next stage lower or "off". The seat ventilation is turned off if the button is pressed for longer than 1.2 seconds.

The system switches down automatically from stage 3 to stage 2 after an running time of 15 minutes. The ventilation remains in stand-by for 15 minutes after KL R off is received.