Turn off the AC unit and unplug it or switch off the breaker
Open the front panel or access cover
Remove the filter carefully
Check the filter type for washability
Vacuum loose dust from the filter
Rinse the filter with lukewarm water if washable
Use mild soap and a soft brush for stubborn dirt if needed
Rinse thoroughly to remove all soap
Shake off excess water
Let the filter air dry completely
Do not reinstall a wet filter
Reinsert the dry filter in the correct direction
Close the panel or cover
Turn the AC unit back on
Clean or replace the filter regularly