More recent freezers don't need to be defrosted as they're frost-free, but they should be washed out and cleaned periodically. When ice builds up, it decreases your freezers ability to chill properly. Follow these simple steps to defrost your freezer when ice builds up to a thickness between 1/4 and 1/2 inches. 

First, turn the freezer off. Then remove all food from the freezer and store it in a cooler while you are defrosting and cleaning the freezer.

Next, remove ice from them the freezer compartment by letting the freezer door stand open until ice melts or using a hair dryer by aiming warm air at ice in the freezer until it melts. Be careful to prevent the hair dryer from getting wet, if you choose this method.

Clean up the ice and water as it melts with a dishcloth or sponge and deposit into sink. Then, use a sponge or dishcloth and a bowl of warm water to thoroughly wipe out inside of freezer once the freezer is ice free.

Now, turn the freezer back on so that it runs for a couple of minutes and return the food to the freezer.