GF83.50-P-0001SX Rear Air Conditioning, Function

GF83.50-P-0001SX Rear Air Conditioning, Function
- with CODE (582) Rear air conditioner


Overall description
The rear air conditioning controls the interior temperature desired by the rear passengers. The rear air conditioning is available immediately after starting the engine. 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 outdoor temperatures and then passes through the heat exchanger where it is heated up to the desired temperature

The function of the rear air conditioning can be summarized under the following list of subfunctions.

^ Heater circuit
The coolant is heated up by the engine. When heat is required, the heated coolant is guided through the left duovalve (A31/1y1) and the right duovalve (A31/1y2) into the rear air conditioning heater heat exchanger. This is where the heat is delivered to the interior air. The coolant returns back to the coolant pump via the heater return.

^ Refrigerant circuit
The refrigerant compressor (A9), which is 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 rear AC refrigerant shutoff valve (Y67) into the evaporator, where it evaporates, cools down and removes 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 rear blower motor (M2/1) and passes through the various air ducts to the air distribution flaps which distribute it in the vehicle interior.

^ Control
The electronic control of the rear air conditioning takes place via different control units and temperature sensors which are connected to one another via the telematics CAN, the interior CAN, the central CAN and the AC-LIN. The desired temperature is achieved or maintained at a constant level by cooling or heating the air.

^ Operation
All functions of the rear air conditioning are controlled via the rear air conditioning control unit (N22/4), via the front central operating unit (A40/9) and via the upper control panel control unit (N72/1) . For settings that are made via the front central operating unit, the display takes place in the COMAND display (A40/8).

^ 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. To do so, the system utilizes the residual heat from the engine and guides it via the blower into the passenger compartment