Frost formation in freezers primarily begins on the evaporator coils. Then when cool, these cold evaporator coils attract moisture from the warm air that enters the freezer (typically when the door is opened). This moisture condenses and quickly freezes upon contact with the cold coils, leading to frost buildup. Over time, this frost acts as an insulator, impeding the coils’ heat absorption capabilities and diminishing the freezer’s efficiency.
The defrost cycle, designed to periodically warm the coils, melts away this frost. However, if the cycle is inefficient or the freezer is frequently opened, allowing more warm, humid air inside, frost can accumulate faster than it is removed, leading to significant build-up inside the freezer.