To replace central heating and air conditioning air filters, turn the air conditioner off, open the housing to the vent, remove the old filter, slide the new filter in and close the housing. Replace the air filters at least every few months.
Air conditioner filters come in a wide variety of sizes. Look at the old filters before heading to the store to buy the correct size. The benefits of changing air conditioning filters regularly include more efficient air flow and a cheaper energy bill, as the air conditioning unit does not have to work as hard to keep things cool.