 Most refrigerators have a sort of a timer built in that will tell you when it's time to replace it, but it's real important that you do replace that because you don't want to let that get too dirty. It's just going to stop working, and it could get to a point where you have some sort of growth happening inside of it that you just don't want. Yeah, now let's move on to the range hood filter. These filters collect grease and smoke and cooking odors, and most of them can be easily removed, cleaned, and then reinstalled. And if you've got a metal filter, you can even run that through the dishwasher.