Refrigerant R744 And Its Effect On Metals And Plastics

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.

In its purest state, refrigerant R744 is chemically stable and does not corrode iron, aluminum, and specially developed and therefore suitable plastics, for example.
However, refrigerant R744 contaminants, such as water or chlorine compounds, cause corrosion of certain metals and plastics. This can lead to blockage, leaks or deposits on the A/C compressor piston.
Certain base metals (magnesium, for example), which are strong reactants, react with carbon dioxide, forming carbon and metal oxides.
Unsuitable materials (such as seals and hoses that were not developed for refrigerant R744 and the refrigerant oil used) can also be affected and damaged by pure refrigerant R744 or refrigerant oil.
If the refrigerant is contaminated with chlorine compounds, for example, then the metals and the plastic developed and approved for this refrigerant and refrigerant oil will be negatively affected. This can lead to blockage, leaks or deposits on the A/C compressor piston.