Convenience automatic air conditioning (C-AAC), function - GF83.40-P-0004TT

MODELS 211.0/2/6 with CODE (581) Comfort automatic air conditioning 

Function 

The comfort automatic air conditioning (C-AAC) [K-KLA] serves to control the interior temperature desired by the driver and passengers. The C-AAC is operational immediately after the engine is started and re-establishes the last stored temperature-controlled condition before the vehicle was locked. System operation is sensitive to moisture and temperature; even at low outside temperatures the ambient air is first cooled down by way of the evaporator's supply of cold air, and then routed through the heat exchanger and set to the desired passenger compartment temperature.

The C-AAC regulates the passenger compartment temperature and the air distribution separately for the driver and passenger sides.

The C-AAC can be summarized with the subfunctions listed below.

• Heater circuit 

  The coolant is heated up by the engine. When heat is requested, heated coolant passes through the heat exchanger shutoff motor (M16/32) to the heater heat exchanger, where heat is dissipated to the interior air. The coolant returns back to the coolant pump via the heater return.

• Refrigerant circuit 

  The refrigerant compressor (A9) driven by the engine compresses the refrigerant vapor which is cooled down in the condenser. The refrigerant liquefies during cooling. The liquid refrigerant passes through the expansion valve into the evaporator, where it evaporates, cools down and removes the heat from the air that is flowing past, therefore cooling it down. The refrigerant compressor (A9) draws in the coolant which has turned gaseous through the collection of heat and compresses it again.

• Ventilation 

  The ventilation system ventilates the interior of the vehicle. The air is drawn in by the blower motor (A32m1) and passes through the various air ducts to the air distribution flaps which distribute it in the vehicle interior.

• Control 

  The electronic control for the C-AAC is accomplished by various control units and temperature sensors connected with one another by the Controller Area Network bus, class B (interior compartment) (CAN-B), Controller Area Network bus, class C (engine compartment) (CAN-C) and the local interconnect network (LIN). The desired temperature is achieved or maintained at a constant level by cooling or heating the air.

• Residual engine heat utilization 

  The residual engine heat utilization feature makes it possible to continue to heat or simply ventilate the vehicle even with the engine shut off. The system makes use of the residual heat of the engine for this purpose.

• Solar stationary ventilation 

(Model 211.0 with code (419) Solar module for panoramic glass roof) 

The solar stationary ventilation ensures air circulation in the vehicle. The solar energy obtained by the solar cells operates the blower motor (A32m1) via the blower regulator (A32n1) and supplies ambient air into the passenger compartment.

This reduces the high temperatures in the passenger compartment. Air circulation increases along with any increase in solar radiation.