How to troubleshoot air conditioning problems in an Audi A2?

I've noticed that the air conditioning in my Audi A2 is not cooling properly. The fan is still blowing, but the air is not cold. What could be causing this issue and how can I fix it?

First, check the air conditioning compressor. It may be faulty and in need of replacement. Also, make sure that the AC refrigerant is at the appropriate level and not leaking. If those are not the issue, then it could be an electrical problem. A diagnosis by a certified mechanic may be necessary.