Refrigerant Circuit, Basic Function - GF83.40-P-1001A

Model All (CAR) 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 
  • Refrigerant circuit 
  • High-pressure side 
  • Low-pressure side 

General 

The refrigerant circuit consists of the following components:

• Refrigerant compressor (1)
• Capacitor (air or water-cooled) (2)
• Evaporator (4)

In addition, as well as the chiller circuit, which includes a plate cooler (heat exchanger (7)) with EXV (8), a check valve and a de-energized closed shutoff valve are also used.

The heat pump is not a separate component, rather an expanded use of the existing refrigerant circuit. To heat the vehicle interior (evaporator (4), battery or drivetrain), the corresponding energy from the respective available waste heat is used here according to the outside temperature.

If it is not possible to reasonably make use of waste heat, a HV-PTC is available in the low-temperature circuit in order to provide the required heating output; in principle, this is possible from the moment of activation of the ignition of heating and cooling mode in the vehicle.

For both operating modes, due to the vehicle architecture, it is necessary for the electric refrigerant compressor (1) to be in operation. In the case of heating, heat is transferred to the heating circuit via the refrigerant compressor (1).

The air conditioning system works in two main operating modes that can also occur in a combined form:

• Heat pump mode
• A/C mode

Function requirements 

• Climate control switched on
• Refrigerant compressor (1) switched on (A/C function).

Function 

Refrigerant circuit 

The individual components of the refrigerant circuit are interconnected through hoses and pipelines and form a closed system.

High-pressure side 

The evaporator shutoff valve is open, and the electric refrigerant compressor (1) sucks in the gaseous refrigerant from the evaporator (4), compresses it and delivers it to the capacitor (2) or the water-cooled capacitor (on e-vehicles).

The compressed, hot coolant is cooled there by the passing airstream or by the coolant depending on the equipment installed. The liquid refrigerant then flows through the liquid reservoir (drier) (3).

The liquid reservoir (drier) (3) removes moisture from the refrigerant, removes vapor locks and filters out mechanical impurities. Downstream of the liquid reservoir (drier) (3), the refrigerant is transported to the thermal expansion valve (8), where the high pressure is reduced and the liquid refrigerant flows into the evaporator (4).

Low-pressure side 

Through the input of heat from the air for the vehicle interior that flows past, conversion from liquid to gaseous state takes place.

The overheated, gaseous refrigerant is then sucked in again by the refrigerant compressor (1) and compressed.

Courtesy of MERCEDES-BENZ USA

Refrigerant circuit (shown schematically on model 177) 

The capacitor (2) is either water-cooled (electric vehicles) or air-cooled depending on the equipment installed in the vehicle. Thermal or electric expansion valves (6, 8) are installed depending on equipment.

Model all (CAR)

with code 582 (Air conditioning, rear)

A second evaporator circuit is also present.