Make sure your FireX 120-5388 smoke alarms are connected to AC power if they are not working.
Remove your FireX 120-5388 smoke alarm from the wall if you hear a constant beeping sound about once a minute.
Open the battery compartment and remove the old batteries. Insert new batteries. FireX 120-5388 smoke alarms use 9 Volt alkaline batteries.
Remove your unit from the wall if it sounds unwanted alarms. Using a hose attached to a vacuum cleaner, vacuum all sides and cover of your smoke alarm. Vacuum all the vents to remove dirt and debris from the sensing chamber.
Remove the batteries. Using a damp cloth, clean the smoke alarm cover. Do not open the smoke detector or attempt to clean the inside.
Press the test button on your smoke alarm for at least five seconds. The alarm horn should sound. If the alarm does not sound, make sure the batteries are inserted correctly.