How to troubleshoot a non-functioning air conditioning system in an Audi A2?

The air conditioning system in my Audi A2 has suddenly stopped working. How can I diagnose and fix the issue on my own before taking it to a mechanic?

First, check the fuse for the air conditioning system. If it's blown, replace it. Next, check the refrigerant levels and top up if necessary. If everything looks fine, the issue could be with the compressor or a leak in the system. In that case, it's best to take it to a mechanic for further diagnosis and repairs.