Automatic air conditioning control and operating unit, task - GF83.40-P-2180-01TM

Fig 1: Identifying Automatic Air Conditioning Control And Operating Unit Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The AAC [KLA] control and operating unit (N22) is responsible for the following tasks:

Switch automatic air conditioning (AAC [KLA]) on and off
Interior compartment temperature selection cold/warm separate for left and right sides
Manual blower control
Manual air distribution
Automatic blower control and air distribution
Air recirculation mode
Defrost function
Heated rear window actuation
Residual engine heat utilization (ECE variant)
Maximum cooling output (USA variant)
Refrigerant compressor shutoff

The AAC [KLA] control and operating unit (N22) is used to actuate the following:

Via the Control Area Network bus, class B (interior compartment) (CAN B):

refrigerant compressor
Heat exchanger shutoff motor

by the driver-side SAM control unit with fuse and relay module

coolant circulation pump

by the passenger-side SAM control unit

Via Controller Area Network bus class C (engine compartment) (CAN-C):

engine and air conditioning electric suction fan with integrated control via the central gateway control unit, and the CDI control unit (with diesel engine) or the ME-SFI [ME] control unit (with gasoline engine)

Via local interconnect network (LIN):

Blower regulator
Fresh air/air recirculation flaps actuator motor
Left blend air flap actuator motor
Right blend air flap actuator motor
Left and right footwell flaps actuator motor
Left and right defroster flaps actuator motor
Center outlet flap actuator motor
Heater booster (with engine 271, 628, 629, 642, 646, 647 and 648)

The following sensor signals are read in by the AAC control and operating unit (N22):

Directly:
- in-car temperature sensor
- evaporator temperature sensor
Via LIN:
- Air humidity sensor (up to 31.8.06)
Via CAN-B from driver-side SAM control unit with fuse and relay module:
- Refrigerant pressure sensor
- Outside temperature display temperature sensor
Via CAN-B by the overhead control panel control unit:
- in-car temperature sensor

Control possibilities

Left temperature selector wheel (1)

Right temperature selector wheel (5)

Turning the left temperature selector wheel (1) or the right temperature selector wheel (5) enables the desired specified temperature to be set for the left or right side.

Increase air volume button (2)

Reduce air volume button (10)

The air volume can be selected manually by operating the Increase air volume button (2) or the Reduce air volume button (10).

The selected air volume setting is shown in the display (3).

Residual heat button (6.1) (ECE variant)

Heating or ventilation can be provided for up to 30 minutes by pressing the residual heat button (6.1). The function is only possible with circuit 15 off or circuit 15C on. If there is low voltage, the residual heat function is automatically switched off. The flaps are in automatic mode. The blower motor operates with a preset fixed value. When the residual heat mode is activated, "REST" lights up in the residual heat button (6.1).

"Max Cool" button (6.2) (USA variant)

Pressing the "Max Cool" button (6.2) raises the basic ventilation value from 40 % to 100 %.

AC button (7)

The refrigerant compressor is switched off by pressing the AC button (7). All other functions are retained.

The function LED in the AC button (7) lights up when the refrigerant compressor is switched on.

Air distribution button scroll up (4)

Air distribution button scroll down (8)

The air distribution button scroll up (4) and the air distribution button scroll down (8) can be used to manually adjust the air distribution.

The selected setting is shown in the display (3).

On/off button (9)

The automatic air conditioning (AAC) [KLA] can be switched off altogether or switched on again by pressing the ON/OFF button (9). The fresh air and air recirculation flap is accordingly closed or opened.

Automatic button (11)

The air volume and air distribution are regulated automatically when the automatic button (11) is pressed. When the automatic mode is active, "AUTO" is shown in the display.

Heated rear window switch (N22s1)

When the button is pressed, the AAC [KLA] control and operating unit (N22) transmits a switch-on request to the rear SAM control unit with fuse and relay module via CAN-B; the function LED in the heated rear window switch (N22s1) is switched on at the same time.

Air recirculation switch (N22s2)

Briefly pressing the air recirculation switch (N22s2) for (< 1.5 s) closes the fresh air and air recirculation flap to prevent air from entering from outside. The function LED in the air recirculation switch (N22s2) lights up during operation. When pressed for a longer period (> 1.5 s), the comfort opening/closing windows and tilting/sliding roof (SHD) (for code (414) Power glass tilting/sliding sunroof) function is activated.

Window defrost switch (N22s3)

The temperature is set to "maximum" and the air flow distributed to the defroster and lateral nozzles. All the other flaps are closed.

The blower is controlled depending on the coolant temperature. The function LED in the window defrost switch (N22s3) comes on.