GF83.40-P-0004GZ Convenience Automatic Air Conditioning (C-AAC), Function
GF83.40-P-0004GZ Convenience Automatic Air Conditioning (C-AAC), Function
- with CODE (581) Comfort automatic air conditioning
Function
The comfort automatic air conditioning (C-AAC) controls the interior temperature desired by the driver and the passengers. The comfort automatic air conditioning is operational immediately after the engine is started and produces 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 interior temperature separately for all 4 seat areas; the air distribution duct separately for driver and passenger side.
The comfort automatic air conditioning can be summarized with the subfunctions listed below:
^ Heater circuit
The coolant is heated up by the engine. When heat is required, heated coolant passes through the heating system heat exchanger where heat is transferred 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 aspirates the refrigerant which has turned gaseous on account of the heat absorption and then compresses it yet 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 comfort automatic air conditioning is controlled electronically via various control units and temperature sensors, which are interconnected via the Controller Area Network bus class B (interior) (CAN-B), the 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 makes it possible to heat or only ventilate the vehicle even when the engine is switched off. The system makes use of the residual heat of the engine for this purpose.
^ Defrosting function
The defrosting function serves for keeping the windows free of fog and ice or quickly eliminating fogged windows by actuating the defroster vent flap to the full open position and closing the footwell flaps. Additionally, the refrigerant compressor is switched on, the position of the fresh air flaps is set to fully open, and the coolant circulation pump (M13) is actuated plus additional heating with the PTC heater booster (R22/3) (with diesel engines).
^ AC OFF function
This function blocks the refrigerant compressor's cut-in. This takes place manually when the button on the comfort AAC [KLA] control and operating unit (N22/7) is pressed. The active AC OFF function is displayed by an LED.
^ Recirculated air, function
The recirculated air function interrupts the fresh air supply from the outside by closing the fresh air/air recirculation flap. This causes the air to circulate (closed windows and sliding roof assumed) in the interior only and keeps unpleasant odors or pollutants at bay. The comfort automatic air conditioning is equipped with an automatic recirculation control.
^ Emission-controlled recirculated air, function
The emissions sensor (B31) transmits the pollutant values of the ambient air to the comfort AAC control and operating unit. The comfort AAC control and operating unit decides on the position of the air recirculation flap together with the dew point sensor (B11/12).
^ Recirculated air convenience feature function
For easier operation, the windows and the tilting/sliding roof (SHD) (with power glass tilting/sliding roof, code 414) are closed automatically when the air recirculation switch (N22/7s2) is pressed for more than 1.5 s. When the air recirculation switch is actuated again, the windows and tilting/sliding roof (SR) return automatically to the previous positions.
