Users can clean or replace the filter in a window air conditioning unit. Some units have reusable filters, which users wash and put back into the air conditioner. Other filters cannot be reused and need to be replaced.
Cleaning or replacing an old, dirty filter can cut energy use of the air conditioner by 5 to 15 percent, according to the U.S. Department of Energy. The owner should wash or replace the air filter once every month during the cooling season to keep dust out of the evaporator coils. More frequent cleaning is necessary if the unit gets used excessively, the area is dusty, or the home includes pets.