Turn off the AC and unplug it or switch off the breaker
Open the front panel or access cover
Remove the air filter carefully
Check the filter for dust, dirt, and damage
Vacuum loose dust from the filter
Wash the filter with lukewarm water and mild soap if it is washable
Rinse the filter thoroughly
Shake off excess water
Let the filter dry completely before reinstalling
Replace the filter if it is damaged or not washable
Reinsert the filter correctly
Close the panel or cover
Turn the AC back on