Instruct: Classify Amazon reviews into positive or negative sentiment
Query: It works for us but not anymore

I read other reviews that say dust get in the fan and stops it. This is true but all you have to do is use a vacuum (the more powerful the better) or do what I do and use compressed air to blow it out. I take it off the wall and unplug it before I do anything. I usually have to do this around once a year. If I don't the unit will turn on but shut itself off after the sensor inside sees that it is getting to hot with the fan not working. I owned mine for about 4 years now and it still works.I do agree that they should have put a bigger fan in it and they also should have put spacers that you can stick on ether side on the back so it will fit snug to the wall. I used pads for wall spacers. These pads normally go under furniture to keep the furniture from markup the wood floors. These pads seems to work very good as wall spacers for me. (put the pad in the back behind both diodes on both sides) it works for about 2 years before it died on us.