Automatic air conditioning, function - GF83.40-P-0005G

MODEL 463.306 /336 /346 as of model year 2011 /YoM 10 

MODEL 463.202 /222 /236 /237 as of model year 2009 /YoM 08 

MODEL 463.247 /248 /249 /254 /270 /271 /303 /340 /341 as of model year 2007 

General function requirements 

• Circuit 15 On

Automatic air conditioning: general 

The regulation and control are carried out by the AAC [KLA] control and operating unit (N22).

The automatic air conditioning is equipped with a separate temperature control for the left and the right half of the vehicle.

Blower control takes place with 1 zone and can be operated manually or controlled automatically.

In vehicles with code (HH7) Additional air conditioning in rear, the rear air conditioning is regulated via the rear air conditioning control unit (N22/4). The rear air conditioning is not integrated into the heating circuit; a separate temperature increase in the rear area is therefore not possible.

The rear air conditioning has no diagnostic capability.

The automatic air conditioning function includes the following partial functions:

• Heating circuit
• Residual engine heat utilization system

Further subfunctions are described in separate documents:

• Ventilation
• Automatic air conditioning control
• Automatic air conditioning refrigerant circuit

Heating circuit function sequence 

Driven by the coolant pump, the coolant circulates in the engine cooling circuit. In the process, it absorbs engine heat. The heated coolant passes through the heater heat exchanger, which dissipates heat to the air blowing by.

Additionally, at low engine RPM, the coolant circulation pump (M13) is actuated to ensure that the flow volume needed to heat up the air blowing by is adequate.

Additional function requirements for residual engine heat utilization 

• C. 15 OFF

Residual engine heat utilization function sequence 

The function is switched on when the Rest button on the control and operating unit is pressed. The control and operating unit forwards the request via interior CAN to the front signal acquisition and actuation module (SAM) (N10/1), which directly actuates the coolant circulation pump.

The coolant circulation pump delivers the coolant (residual heat) that is still warm through the heater heat exchanger. At the same time, the control and operating unit forwards the ventilation request via the AC bus to the blower regulator (A32n1), which then actuates the blower motor with an output of 25 %.

The air drawn in by the blower motor is routed along the heater heat exchanger and thus heated up.

The function is terminated after a time of t = 30 min has elapsed or when the on-board power supply voltage drops below a certain value.

	Automatic air conditioning, location of components		GF83.40-P-0005-01G
	Automatic air conditioning, block diagram		GF83.40-P-0005-02G
	Ventilation system, function		GF83.10-P-2000GB
	Regulation of Automatic air conditioning, function		GF83.40-P-2004G
	Automatic air conditioning refrigerant circuit, function		GF83.40-P-2005G