The tech (lets not call him a tech anymore) also added uv dye to check for leaks. I know on my vw polo the agents have an automatic device to evacuate both gas and oil in the system.Does Mercedes use a similar system and should I have other components replaced in the system ( for the technicians bill of coarse!

Also,If the system is changed to R134a what components needs to replaced as I believe this gas operates at a higher pressure?

Yeh lots of questions, buts that the only way for me to learn.

Thanks