Refrigerant Circuit Pressures And Temperatures: Notes

The pressures and temperatures in the refrigerant circuit depend on the current operating conditions (such as engine speed, radiator fan level 1, 2 or 3, engine temperature, A/C compressor on or off) as well as on the effects of ambient influences (such as ambient temperature, humidity, desired cooling output).

In vehicles with a A/C Compressor Regulator Valve -N280-, the pressure is altered on the low pressure side by the activation of the A/C Compressor Regulator Valve A/C Compressor Regulator Valve -N280-.

On vehicles with an Electrical A/C Compressor -V470-, the refrigerant circuit pressure (high and low pressure sides) is regulated via the A/C compressor speed.

On vehicles with an Electrical A/C Compressor -V470-, where the A/C system not only cools the vehicle interior but also cools the high-voltage system components and is used as a heat pump to heat the vehicle interior, other conditions, pressures and temperatures in the refrigerant circuit apply (for example, in the Audi Q7 e-tron). Use the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function and refer to Refrigerant Circuit (vehicle-specific Service Information).

For this reason, values indicated in the following table are valid only as reference points. They are attained at an engine speed of 1500 to 2000 RPM and an ambient temperature of 20 °C (68 °F) after approximately 20 minutes.

The pressure gauge battery connections intended for the pressure measurement are indicated in the vehicle-specific refrigerant circuit. Refer to Refrigerant Circuit (vehicle-specific Service Information).

At 20 °C (68 °F) with the engine not running, the pressure in the refrigerant circuit is 4.7 bar (68.17 psi). Refer to Refer to REFRIGERANT R134A VAPOR PRESSURE TABLE  (vapor pressure table).