At least once a year a window air conditioner must receive routine maintenance, or else the unit's performance and efficiency may degrade while the risk of breaking down increases. A window air conditioner must be removed from the window for proper maintenance.
Unplug the unit, remove the front access cover, and take it outside to vacuum the condenser coils carefully with a brush attachment. Dust and debris accumulate over time on the condenser coils, and the cooling fins may bend. Straighten any bent fins with a coil fin comb, being careful to not bend any other fins.
Replace the foam air filter if it is damaged. If it is dirty, then wash it with dish soap and water, allowing it to dry before putting it back into the air conditioner.