Your refrigerator's capacitor is responsible for keeping the appliance working properly. Capacitors store up an electric charge and then release it whenever the refrigerator motor needs to run, kicking that motor into action. If this device isn't working correctly, your fridge may fail to cool food or function erratically. Capacitors can be dangerous, and require careful handling during refrigerator maintenance and repair.
A capacitor is an element in an electric circuit that stores a charge for a short period of time. Also called condensers, these devices contain two or more conductors separated by an insulating material called a diaelectric. The capacitor in your refrigerator may be rectangular, with two or more metal conductors protruding from one side, or cylindrical, with the conductors on top.
A fridge capacitor is responsible for starting the motor on the compressor system, the part of the refrigerator that pushes coolant through the coils. When the inside of the refrigerator begins to warm up, the capacitor discharges, starting the compressor motor. The compressor pushes refrigerant into the condenser for cooling, then into the evaporator, where it draws heat away from the fridge interior. The warm coolant than goes back to the condenser.
If you think your fridge capacitor has failed, you can test it using an insulated screwdriver. For capacitors with bare metal terminals, hold the metal end of a screwdriver with an insulated handle across both terminals at the same time, creating a short. If your capacitor has coated terminals, you will need to short the capacitor using insulated needle nose pliers. Use an ohm meter to test the capacitor terminals one at a time. The needle should move slightly, then return to its original position. If the needle doesn't move at all, or stays in position, you may need to replace your capacitor.
Because capacitors store large amounts of electricity, they can discharge suddenly if they come into contact with a metal object or human skin. Small capacitors produce only a painful shock, but large capacitors, such as those found in refrigerators, can injure or kill a person. Make sure you discharge this part fully before you do any work on a refrigerator that uses a capacitor. To discharge your fridge's capacitor, the website Acme How To recommends two screwdrivers attached to a 20,000 ohm resistor via jumper wires. Touch one screwdriver to each terminal on the capacitor, but do not touch the capacitor itself during this process, as it may become hot.