Topping up the aircon? Yourself? Do you have the machine that does that job for you?
You cannot simply add some fluid to the system. The system is vacumated (is that a correct English word?). The fluid that is in the system must be taken out. You need a special machine to do the job. Than the machine vacumates and fill the system with new coldfluid (530) and oil (10).
The filling points are on the aluminium tubes of the aircon system.
Greetings,
Maurice