Pressure Relief Valves

WARNING: This page is about a different car, the 2022 Volkswagen ID.4 and 2021 Volkswagen ID.4. However, it is still accessible from the selected car via links, so may be relevant.

Pressure relief valves -A- protect the refrigerant circuit from pressure that is too high.

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Pressure relief valves -A- without the additional seal are currently installed. The system is sealed via the sealing surface -B-.
Pressure relief valves -A- may only be installed one time.
When the A/C system is operating, the pressure relief valve on the high-pressure side will open if there is too high of a pressure on the high-pressure side and the other components protecting the refrigerant circuit do not turn off the A/C compressor activation as intended.
The pressure relief valve on the low-pressure side will open if there is too high of a refrigerant circuit pressure when the vehicle is stationary (for example, if the A/C system is overfilled or the ambient temperatures are too high).
The pressure relief valve on the high-pressure side may be installed on the A/C compressor, for example. Refer to Refrigerant Circuit (vehicle-specific Service Information).
The pressure relief valve on the low-pressure side may be installed on the refrigerant line with the inner heat exchanger, for example. Refer to Refrigerant Circuit (vehicle-specific Service Information).
The pressure relief valve on the high-pressure side opens at a pressure of approximately 160 bar (2, 320.61 psi) (up to a maximum of 170 bar (2, 465.65 psi)) and closes again once the pressure has dissipated (at approximately 150 bar (2, 175.57 psi)).
The pressure relief valve on the low-pressure side opens at a pressure of approximately 120 bar (1, 740.46 psi) and closes again once the pressure has dissipated (at approximately 110 bar (1, 595.42 psi)).
Refrigerant does not escape completely.
The pressure relief valves have different threads so that they cannot be interchanged. For example, the pressure relief valves on the high-pressure side currently have a M12 x 1 mm left-hand thread and the pressure relief valves on the low-pressure side have a M14 x 1 mm left-hand thread.
The protective film -B- protects the pressure relief valve by preventing any dirt or moisture from entering.

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
If the protective film is damaged, the pressure relief valve -A- must be replaced.