GF83.40-P-0004Q Comfort Automatic Air Conditioning (C-AAC), Function
GF83.40-P-0004Q Comfort Automatic Air Conditioning (C-AAC), Function
- except CODE (581) Comfort automatic air conditioning
Function
The comfort automatic air conditioning (C-AAC) regulates the desired passenger compartment temperature in accordance with the driver or passenger needs in terms of heating, cooling and air distribution. The air conditioning is fully operational after starting the engine and restores the last stored temperature status before locking the vehicle. The system operates on the basis of the humidity and temperature. The ambient air is first cooled down by adding cooled air from the evaporator, even at low outside temperatures, and then passes through the heat exchanger where it is heated up to the desired interior temperature. The C-AAC regulates the passenger compartment temperature and the air distribution separately for the driver and passenger sides.
The C-AAC utilizes the signals of the outside temperature display temperature sensor (B14) together with the C-AAC sun sensor (4 in total) (B32/2), the C-AAC multifunction sensor (B31) and the soft top status as input signals for calculation of air distribution, temperature control and blower motor regulation. The evaporator temperature sensor (B10/6) measures the temperature at the air outlet of the evaporator while the in-car temperature sensor (N22/7b1) measures the interior temperature.
For vehicles as of 1.6.05, the interior temperature is also determined by the in-car temperature sensor (N70b1) in the overhead control panel control unit (N70).
The comfort automatic air conditioning (C-AAC) function can be summarized under the following list of subfunctions.
^ Ventilation
Ventilation ensures aeration in the vehicle interior. Ventilation is achieved with the support of the blower motor (A32m1) during normal operation, when vehicle is stationary or to increase the air flow. The air is distributed in the vehicle interior via air distribution flaps.
In order to prevent window fogging, the footwell flaps are opened fully for 30 seconds after the ignition has been switched on.
When the ignition is switched off, the fresh air/recirculation flap is automatically moved into a 50 % fresh air and 50 % recirculated air position.
^ Temperature control for convenience automatic air conditioning
The desired temperature is achieved or maintained at a constant level by cooling or heating the air. An exact temperature control is achieved by the reading in various temperature sensors.
^ Regulation for convenience automatic air conditioning
Control of the comfort automatic air conditioning takes place using various control units that are interconnected via the class B Controller Area Network bus (interior) (CAN-B). The CAN-B is a bidirectional bus, i.e., each connected control unit receives and transmits information.
^ Heater circuit
Coolant is heated via the engine. The heated coolant is subsequently guided through the heat exchanger, where the heat is emitted into the air in the interior. Via the heater return, which contains the hot water recirculation pump (M13), the coolant is returned to the coolant pump.
The hot water recirculation pump (M13) ensures that the coolant is circulated.
The coolant flows through the heating system heat exchanger permanently.
Temperature control, depending on the temperature desired in the vehicle interior, is carried out via the blending air flaps, which are activated - separately for the left and right side - via the left (M2/6) and right (M2/7) blending air flap actuator motor.
^ Refrigerant circuit
The refrigerant compressor (A9) compresses the refrigerant vapor which is heated up during the process, routed into the condenser and thus cooled down. After being cleaned in the fluid reservoir, the liquid refrigerant is injected into the evaporator. The refrigerant evaporates and cools down while doing so. The refrigerant compressor (A9) again intakes the refrigerant, which has returned to its gaseous form as a result of heat absorption.
^ Residual engine heat utilization
Residual engine heat utilization enables the vehicle to be heated even when the ignition is OFF. To do so the system utilizes the residual heat from the engine and leads it into the passenger compartment via the blower motor (A32m1). The hot water recirculation pump (M13) ensures that the coolant is circulated.
