General Description - Refrigerant Circuit Components: Evaporator
There are different versions of the evaporator. Depending on the design and the function, the heat energy of the flowing air needed (for example, on the evaporator in the heater and A/C unit or in the battery cooling module) or flowing coolant needed (for example, near the high-voltage battery heat exchanger) is extracted for refrigerant evaporation. Refer to Refrigerant Circuit (vehicle-specific service information).
Two versions of the evaporator are described in the following.
Evaporator in the Heater and A/C Unit (or in the Battery Cooling Module)
- The liquid refrigerant evaporates in the evaporator pipe -A-. The heat required for this is extracted from the air drifting by the evaporator ribbing -B-. The air cools off. Refrigerant evaporates and is extracted with the absorbed heat by the A/C compressor
- A definite quantity or refrigerant is supplied to the evaporator through an expansion valve (a restrictor). In systems with an expansion valve, the flow rate is regulated so that only gaseous refrigerant escapes the evaporator output.
- With the introduction of the refrigerant R1234yf, the evaporators were adapted to the refrigerant; therefore, make sure the correct version is used. Refer to the Parts Information.
Evaporator / High-Voltage Battery Heat Exchanger (Chiller)
The liquid refrigerant evaporates in the evaporator (heat exchanger). The heat required for this is extracted from the coolant flowing through the evaporator. The coolant cools, the refrigerant evaporates and is extracted with the absorbed heat by the A/C compressor.
A defined amount of refrigerant is supplied to the evaporator by a restrictor (or expansion valve) and a shut-off valve. The flow rate of the refrigerant (or the coolant) is regulated so that only gaseous refrigerant escapes the evaporator output. Refer to Refrigerant Circuit (vehicle-specific service information).