A refrigerator relay, or start relay, jump-starts the refrigerator's compressor. Without the relay, no electrical charge is delivered to the compressor and the refrigerator does not cool. Relays usually make a loud clicking noise when they are in need of repair or replacement.
The relay is located on the lower back section of most refrigerators. It is protected by the terminal cover box and is plugged directly into the back of the compressor. Most relays have a set of copper coils, which, like the terminal on the compressor, must be kept clean and free of corrosion. Minor corrosion may be cleaned off using metal cleaner, but, like a car battery, if the corrosion is too severe, the relay might need to be replaced.
Solid state relays are becoming more popular. They use rotors to generate the power needed to start the compressor. When the compressor starts, it feeds electricity back into the relay that is maintained as long as the compressor is running. When the compressor shuts off, the rotors slow down,and the relay cools and gets ready for the next start. Once the rotor spin dips to between 60 to 80 percent of its full speed, the compressor starts again.