[header] How to clean an air conditioner [title] Replace the air filter. [step] Purchase a new air conditioner filter at your local home improvement store. Consult your owner's manual for the correct size, or take your old filter to the store with you. 
[title] Turn off the power to your furnace or blower. [step] If you can't find the shutoff switch on the unit, then turn it off at the main panel.