I’ve been trying to understand this unit, so my review has taken a little longer than it should. It doesn’t have a fan. The only way I could tell it was working was a little green light on top. But the other night I was making fried potatoes, and my kitchen was pretty stinky. So I bought in the air purifier to see what it would do. Didn’t take long at all and the air was back to breathable. This is a very quiet unit great for sleeping areas since it doesn’t make any noise, it seems to work extremely good. Overall I’d have to give it a five star