Diagnosis
The air filter is located behind the front grille. It is not immediately obvious as the grille does not have a clear pull tab.
How to Fix It
Power off and unplug the unit. Locate the two small notches on the left and right sides of the front plastic panel. Press firmly inward on both sides while pulling the entire grille toward you. The rectangular foam filter will be attached. Rinse it under lukewarm water, let it dry completely, and reinstall.
If That Didn't Work
If the grille will not release, check for hidden screws along the top edge. Some variants may have one or two screws securing the grille from underneath or on the sides.
Heads Up
Do not operate the unit without the filter. A clogged filter is the most common cause of reduced airflow, poor cooling, and premature compressor shutdown.