Level control valve unit, component description - GF32.31-P-5115SX

MODEL 221 with CODE (489) Airmatic (semi-active air suspension) up to Model Year 8

The AIRmatic central reservoir charge valve (Y36/6y5) is integrated in the level control valve unit and is mounted behind the right headlamp.

Fig 1: Identifying Level Control Valve Unit And AIRmatic Compressor Unit

Courtesy of MERCEDES-BENZ USA

Fig 2: Identifying AIRmatic Pressure Sensor And Level Control Valve Unit

Courtesy of MERCEDES-BENZ USA

The following are integrated in the level control valve unit:

The four level valves
The AIRmatic central reservoir charge valve
The AIRmatic pressure sensor

Level valves

The adjustment of the vehicle level can be changed via the four level valves. If one of the level valves is actuated, air can be delivered into the corresponding bellows via the AIRmatic compressor unit (A9/1) in order to raise the vehicle level.

If the AIRmatic pressure reduction valve (A9/1y1) in the AIRmatic compressor unit is operated simultaneously when the level valve is operated, air can escape from the bellows and the vehicle level drops.

AIRmatic central reservoir charge valve

The AIRmatic central reservoir charge valve is required for filling the level control valve unit or for filling the suspension struts with compressed-air from the AIRmatic central reservoir.

If the AIRmatic with ADS control unit (N51) records too low a pressure via the AIRmatic pressure sensor while driving, the AIRmatic compressor unit is switched on as well as the AIRmatic central reservoir charge valve actuated and compressed-air is delivered into the central reservoir.

If the necessary pressure is reached, the compressor unit is switched off and the AIRmatic central reservoir charge valve is closed.

The function is active as of a speed of over 40 km/h (when accelerating), or up to a speed of more than 20 km/h (when braking).

The upper cutoff pressure for the central reservoir charging depends on the current atmospheric pressure. The atmospheric pressure is obtained from the ME control unit via the chassis CAN (N3/10).

If the compressed-air stock is used to raise the vehicle, the AIRmatic central reservoir charge valve and the corresponding level valve is opened. With a corresponding pressure difference between the level control valve unit and the bellows, compressed-air escapes into the corresponding bellows. The vehicle level is raised.

The four level valves are supplied via a common line.