It is just as important to correctly install your filter as it is to change it. It is easiest to change your filter if your unit isn’t active, if it is, turn it off. After locating the air filter housing, look at how it is sitting in the slot and make note of the direction the arrow is pointing. You may even want to consider marking the arrow direction on the frame of the housing with a permanent marker to make sure you always put it in the correct air-flow direction. Then, pull the old filter out, match up the arrows on the frame and the clean filter and slide the new air filter into the housing. That’s it!