Check Valves
WARNING: This page is about a different car, the 2021 Audi S4 and 2021 Audi A4 Quattro. However, it is still accessible from the selected car via links, so may be relevant.
The check valves disconnect in different areas of the refrigerant circuit.
NOTE:
For example, the illustrated check valve -3- is installed on an Audi Q7 e-tron.
The check valves in the refrigerant circuit in the flow direction have a specified residual pressure, approximately 0.1 bar or 100 mbar (1.5 psi). So that the refrigerant circuit can be completely evacuates (residual pressure less than 5 mbar (0.10 psi)) all electrically activated valves must be opened.
Depending on the version the flow direction can be marked using a sticker.