Frost buildup generally begins on the evaporator, or cooling coil within the freezer.?This component consists of a series of copper tubes, which refrigerant runs through to keep the refrigerator and freezer compartments cool.?In a frost-free appliance, a defrost heater is positioned near or woven through the evaporator coils to melt frost as it forms.?This heater commonly takes the form of a simple wire filament enclosed within a glass or aluminum tube.?As electricity runs through the wire, it heats the tube and melts nearby frost.?A drip pan sits below the evaporator to catch liquid and condensation, which eventually evaporates from the pan http://www.etdzheater.com