Component description for automatic air conditioning control unit - GF83.40-P-3012LEH

MODEL 221.095/195

Fig 1: Identifying Automatic Air Conditioning Control Unit

Courtesy of MERCEDES-BENZ USA

Location

The AAC [KLA] control unit is located on the front side of the air conditioner housing on the passenger side.

Task

The AAC [KLA] control unit has the following tasks:

Control of the vehicle climate control
Reading in of sensors and signals
Evaluation of input factors
Actuation of components

Control of the vehicle climate control

The AAC [KLA] control unit is the master control unit for the climate control of the vehicle interior and controls or regulates the following functions:

Automatic air conditioning ON/OFF
Overall automatic system
Regulation of interior temperature, blower output and air distribution, separately for the left and right vehicle sides
Adaptation of the footwell temperature
Adjustment of the air flow intensity
Defrosting
Open/close recirculated air
Residual engine heat utilization system
Coupling of all setting zones with driver zone
Stationary heater climate control function (with code (228) Stationary heater)
Remote control of rear automatic air conditioning (with code (582) Rear air conditioning)

Automatic air conditioning functions are operated via the upper control panel control unit (N72/1) or the front central operating unit (A40/9). With code (582) Rear air conditioning, the requests of the rear air conditioning control unit (N22/4) are sent via telematics CAN (CAN A) to the COMAND controller unit, via central CAN (CAN F) to the central gateway control unit (N93) and from there forwarded via interior CAN (CAN B) to the AAC [KLA] control unit.

Reading in of sensors and signals

The input factors are read in with the following connections:

Direct line
A/C bus (KB)
Interior CAN

Direct line

The signals from the following components are read via a direct line:

In-car temperature sensor (B10/4)
Evaporator temperature sensor (B10/6)
Left side outlet temperature sensor (B10/31)
Right side outlet temperature sensor (B10/32)
Left footwell temperature sensor (B10/35)
Right footwell temperature sensor (B10/36)
Left side air outlet potentiometer (R41/1)
Right side air outlet potentiometer (R41/2)
Left front center air outlet potentiometer (R41/3r1)
Right front center air outlet potentiometer (R41/3r2)

In addition with code (582) Rear air conditioning:

Left rear air conditioning heat exchanger temperature sensor (B10/9)
Right rear air conditioning heat exchanger temperature sensor (B10/10)
Rear air conditioning evaporator temperature sensor (B10/11)
Left rear center air outlet potentiometer (R41/4r1)
Right rear center air outlet potentiometer (R41/4r2)

AC bus

The following sensors are read in via the A/C bus:

AAC multifunction sensor (B31/1)
AAC [KLA] 4-way sun sensor (B32/2)

The sensors are connected to the front SAM control unit. The data is only looped through, however, and read in by the AAC [KLA] control unit.

Interior CAN

The signals are read in by the AAC [KLA] control unit via the interior CAN.

The functions resulting there from are described in the corresponding function descriptions (see block diagram or function schematic).

Evaluation of input factors

The input factors that have been read in are evaluated by the integrated microprocessor and the affected components are then actuated.

Actuation of components

Components are actuated with the following lines:

Direct line
Climate control LIN (LIN B8)
Interior CAN

Direct line

The following components are directly actuated with code (582) Rear air conditioning:

Delivery unit for rear heating system (A31/1)
Rear air conditioning electronic blower regulator (N29/2)
Rear AC refrigerant shutoff valve (Y67)

Climate control LIN

The following components are actuated via climate control LIN:

Blower regulator (A32n1)
Fresh air/air recirculation flaps actuator motor (M2/5)
Left defroster vent flap actuator motor (M2/8)
Right defroster vent flap actuator motor (M2/9)
Left footwell flap actuator motor (M2/10)
Right footwell flap actuator motor (M2/11)
Left center air flap actuator motor (M2/12)
Right center air flap actuator motor (M2/13)
Left side outlet flap actuator motor (M2/17)
Right side outlet flap actuator motor (M2/18)
Upper left blend air flap actuator motor (M2/30)
Lower left blend air flap actuator motor (M2/31)
Upper right blend air flap actuator motor (M2/32)
Lower right blend air flap actuator motor (M2/33)
Left rear center air vent actuator motor (M16/19) (with code (582) Rear air conditioning)
Right rear center air vent actuator motor (M16/20) (with code (582) Rear air conditioning)
Left B-pillar air distribution actuator motor (M16/33)
Right B-pillar air distribution actuator motor (M16/34)

Interior CAN

The signals are transmitted by the AAC [KLA] control unit via the interior CAN.

The functions resulting therefrom are described in the corresponding function descriptions (see block diagram or function schematic).

	Wiring diagram for automatic air conditioning (AAC) control unit	Sheet 1	PE83.40-P-2101-97SAA
		Sheet 2	PE83.40-P-2101-97SAB