What is the best way to clean my air conditioning system in my Audi A2?

I have noticed that my car's air conditioning isn't as cold as it used to be. How can I properly clean and maintain the system in my Audi A2 to improve its performance?

The first thing you should do is check the cabin air filter. If it is dirty or clogged, it can prevent the air from flowing properly and decrease the efficiency of your A/C system. It is recommended to replace the cabin air filter every 12,000-15,000 miles.