DIAGNOSIS Regular cleaning is crucial for performance, and the main targets are the air filter, the evaporator coils you can see behind it, and the bucket.
FIX 1. Unplug it. 2. Pull out the bucket and wash it with warm soapy water. Rinse and dry it completely. 3. Remove the air filter by pulling the tab. Vacuum it or wash it in lukewarm water. Let it dry FULLY before putting it back. 4. With the filter out, use a vacuum cleaner hose with a brush attachment to gently vacuum the aluminum fins (coils) you see. Be careful not to bend them. 5. Wipe down the exterior grille with a damp cloth.
IF THAT DIDN'T WORK If performance is still poor after cleaning, there might be mold or heavy dirt deep in the coils you can't reach. You can use a can of coil cleaner foam from a hardware store, sprayed lightly onto the coils from the front, following its directions carefully. Let it foam and drain, and let the unit dry for a day before use.
HEADS UP Never use harsh chemicals, steam cleaners, or pressure washers. Don't try to remove any panels to get to the back of the coils—you'll break seals and void your warranty.