Why does my Audi 80 make a strange noise when I turn on the AC?

I've noticed that whenever I turn on the AC in my Audi 80, there's a weird noise coming from the engine. It's not a loud noise, but it's definitely noticeable. What could be causing this and is it something I should be worried about?

The most likely cause of this noise is a clogged or dirty air filter. When the air filter is clogged, it restricts the airflow to the engine and can cause strange noises. It's important to regularly clean or replace your air filter in order to avoid potential engine issues.