Pressure Relief Valve
The pressure relief valve is installed on the A/C compressor or receiver/dryer.
At a pressure of approximately 38 bar (551 psi) positive pressure, the valve opens and closes again once pressure has dissipated (approximately 30 bar (435 psi)).
Refrigerant does not escape completely.
Depending on the version, a transparent plastic washer -B- may be installed on the pressure relief valve -A-, which breaks off as soon as the valve is activated.
Courtesy of AUDI OF AMERICA, LLCDepending on the pressure relief valve version -A-, an additional cover -C- can be slid onto the pressure relief valve -A-. If the pressure in the refrigerant circuit does rise above the pressure relief valve -A- opening pressure and the pressure relief valve opens, the refrigerant does not escape in one direction, but rather it is distributed through the openings -D- under the cover -C-.
If it is necessary to replace a pressure relief valve -A- pay attention to the tightening specification when installing (depending on the manufacturer of the A/C compressor and the version). On "Denso" (or "Nippondenso"), "Sanden" and "Zexel/Valeo" A/C compressors, an O-ring is installed (tightening specification currently 10 Nm on "Denso" and "Zexel/Valeo" as well as 15 Nm on "Sanden" A/C compressors). On a "Delphi" A/C compressor, for example, a seal is installed (tightening specification is currently 15 Nm).
Replace the seals (seal or O-ring). Refer to the Parts Information.
If the seals (seal or O-ring) that are installed on the pressure relief valve are not available as a replacement part, the removed seals may be used as an exception (check for damage before installing). If the removed seal is damaged or deformed if necessary replace with a commercially available component. Refer to the Parts Information.
After charging the refrigerant circuit, check the installed pressure relief valve for leaks using an electronic leak detector, for example.