It is important to have a set schedule on the maintenance of an AED unit. You will need to follow the manufacturer's recommendations and your in-house policy. Maintenance means visually checking the unit for damage or dirt as well as checking the pads, battery and function of the unit. AED units will usually have warning lights and sounds to indicate that something is wrong. Checks on the unit should be recorded for future reference. You should monitor expiry dates carefully and make sure that you order new pads and batteries in plenty of time. Check your order when you receive it and make sure that you check and make a note the date of expiry.