What is a Defrost Heater?

A defrost heater is a component located within the freezer section of a refrigerator. Its primary function is to melt the frost that accumulates on the evaporator coils, ensuring the efficient operation of the cooling system. When frost builds up on these coils, it hampers the refrigerator’s ability to cool effectively, leading to higher energy consumption and potential food spoilage.

The defrost heater usually turns on periodically to perform its designated function, allowing the refrigerator to maintain optimal temperatures. By understanding the defrost heater’s role, you will be better equipped to troubleshoot any issues that may arise, thereby prolonging your appliance’s lifespan.

How Does a Defrost Heater Work?
The operational mechanism of a defrost heater is quite fascinating. Typically, it is controlled by the refrigerator’s defrost timer and thermistor. Here’s a deeper look at the process:

The Defrost Cycle
The defrost cycle is initiated at specific intervals, usually every 6 to 12 hours, depending on the refrigerator model and the environmental conditions surrounding it. The cycle works as follows:

Defrost Timer Activation: The defrost timer signals the defrost heater to turn on.
Heat Generation: The heater generates heat, which is directed towards the evaporator coils.
Frost Melting: The heat melts the accumulated frost, turning it into water, which then drains away.
System Reset: Once the frost melts, the defrost timer switches off the heater, and the cooling cycle resumes.
Types of Defrost Heaters
There are typically two main types of defrost heaters used in refrigerators:

Electric Defrost Heaters: These heaters use electrical resistance to generate heat. They are the most common type and are found in most modern refrigerators. Electric defrost heaters can be either ribbon-type or wire-type, designed to provide uniform heating across the evaporator coils.
Hot Gas Defrost Heaters: This method utilizes compressed refrigerant gas from the compressor to produce heat. The hot gas is directed through coils, melting the frost as it passes, allowing for a faster defrost cycle. While this method is efficient, it is less common in household refrigerators than electric heaters.