How can I tell if my Audi A2 has a faulty AC compressor?

I recently purchased a used Audi A2 and have been experiencing issues with the AC. How can I determine if the AC compressor is faulty and needs to be replaced?

One way to tell if your AC compressor is faulty is to check for a clicking or rattling noise when the AC is turned on. This could indicate a bad compressor.

Another sign of a faulty AC compressor is if the AC is blowing warm air instead of cold. This could be a result of the compressor not working properly.