A refrigerator that functions properly should run through cycles where the compressor runs and shuts off in order to keep the interior of the fridge at a stable temperature. There are many reasons why a refrigerator may run constantly. Some causes, like a high thermostat setting, are easily fixed. Other problems may require a qualified professional to repair.
New refrigerators may run constantly when you first turn them on. It can take up to 24 hours before the temperature is cool enough inside your fridge. Empty refrigerators may take longer to achieve a stable interior temperature. If there is very little in the fridge and the door is opened and closed, the temperature will fluctuate. Fill the refrigerator at least half full to help keep an even temperature inside.
If the door sags or has a damaged gasket, then the warmer air outside may be getting inside your fridge, causing the interior temperature to increase. Frequently opening and closing the door, or leaving it open for long periods can also cause the refrigerator to keep running for long periods. This is a common problem in hot, humid weather.
The thermostat turns your refrigerator's compressor on and off. The compressor, when switched on, runs until the temperature inside is lower than the thermostat setting, and then it stops. When the temperature gets higher than the thermostat setting, the compressor is switched on again. If the thermostat is not working properly, your compressor may run constantly. The thermostat may also be set too high, forcing the refrigerator to run the compressor to maintain the cooler temperature. Try lowering the temperature. If this stops the compressor from running, then you had the thermostat set too high. If it does not, you may need a new thermostat.
If the thermostat is working properly but your fridge still runs constantly, the problem may be caused by refrigerant leaking into the sealed system. Legally, only an EPA certified technician can fix this problem. If you attempt to fix it yourself, you may permanently damage your refrigerator and void the warranty.
The condenser coils, typically located on the back of the refrigerator, require room to move the heat away from the refrigerator. If they are dirty or too close to a wall, they will not be able to radiate heat away, and this can cause the refrigerator to warm up and run more often to cool it down. Move your fridge away from wall and make sure there is space on all sides to allow for air to pass through. If the coils are dusty or dirty, clean this away.
Broken Light Switch
Check the light switch, typically found on the door of your fridge. Push the switch in to ensure the light is shutting off when you close it. If the light does not turn off, it can warm the interior of the fridge and cause it to run in order to reach the thermostat setting temperature. If it is not shutting off, you may have to replace the switch.