Hi,I’m about to replace the compressor on my L322. How do I disconnect the airline.Is it a twist and pull action using grips of some description?

Put an open ended 6mm spanner over the plastic airline next to the coupling and press it sideways against the coupling. This will press in the small collar. At the same time pull the pipe out of the fitting.
To refit the pipe simply push in the pipe until it can’t be pushed in further.