There won't be any animals in the air-conditioning duct, and they are under great pressure if they can't get in. If there are pinholes 1%, it will cause fluorine leakage, which is the sound generated by refrigerant flow when air conditioning is running, but the ordinary sound is similar to the sound of running water, except that you may have some changes, but in short, you can feel this sound when you pay attention. It sounds good. When you listen to it as music, you won't feel upset. Just try it.
Supplement: Ha, there is a mistake. It's possible. I suggest you put some rat poison or pesticide in it, which will be effective.