Under certain conditions your refrigerator will run for extended periods -- even if it’s in perfect working order. For example, a brand new refrigerator needs to stabilise itself by first cooling its built-in insulation; a large appliance could take up to 48 hours before the compressor starts cycling on and off. Here’s another example: During hot and humid conditions the compressor has to work almost constantly to cope with the load – especially if you have recently packed your refrigerator with warm food and beverages. However, there are a number of other correctable faults and conditions you should be aware of.
A refrigerator with a condenser coil grid mounted on the back needs circulating air to cool down and radiate waste heat into the atmosphere. Allow adequate clearance by positioning this type of refrigerator at least 100 mm away from the wall.
Rear mounted condenser coils can become tacky from grease-laden steam after extended periods. This allows an insulating layer of air born dust to stick to the coils and prevent adequate cooling. Inspect the back of your refrigerator periodically. If the condenser coil looks dirty, unplug the refrigerator and wipe the grime off with a mixture of warm water and detergent. Some refrigerators have the condenser coils and cooling fan mounted underneath the fridge. Unplug the unit and use a long-handled bristle brush and vacuum cleaner to clean this type of condenser at least once a year.
A sparsely packed refrigerator contains a large amount of free air that must be kept cold, and this takes a lot of refrigeration power. Try to minimise empty space by keeping your fridge approximately three quarters full at all times. If you only do your grocery shopping every fortnight or once a month, fill several two litre plastic bottles with water and pack them in your food compartment. In addition to reducing the amount of cold air cascading out of the fridge when the door is opened, the cold water will help to keep the interior cool without overworking the compressor.
The food compartment thermostat maintains a constant interior temperature by turning the compressor on and off as required. During the cooling cycle, the compressor runs until the interior temperature falls below the thermostat set point. However, if the thermostat is set too low, the compressor will keep on running until the interior finally cools down enough. To make matters worse, this may never happen, because every time you open the door, heavy cold air spills out, taking the compressor back to square one. If your ice cream is brick hard when you take it out of the freezer, and if you notice ice crystals in your beverages, your thermostat is set too low. Adjust the thermostat to raise the temperature setting and see if that makes the compressor cycle on and off normally. Use a refrigerator thermometer to help set the temperature to the point where lettuce stays crisp, beverages remain frosty but not ice-bound, and your ice cream in the freezer remains firm but not frozen solid. If you’re able to scoop out a spoonful of ice cream without bending the spoon handle, the freezer is cold enough to prevent frozen food from spoiling.
If your refrigerator compressor keeps running after adjusting the temperature to a higher setting, the food compartment thermostat is faulty and must be replaced. In addition, if you own a frost-free refrigerator, the appliance is fitted with a second defrost thermostat. This unit is attached to the interior evaporator coil to sense temperatures. When the coils get too cold to the point where insulating frost and ice starts forming on the coil surface, the thermostat shuts the compressor down and turns the defrost heater on. When all the ice packed around the coil has melted, the thermostat shuts down the heater and turns the compressor back on. However, if the thermostat fails and prevents the defrost cycle from kicking in, ice continues to build up on the evaporator coil, the compressor runs constantly. and the refrigerator efficiency is impaired by layers of insulating ice. If you notice a thick layer of ice forming in your freezer compartment, it may be time to replace either the defrost thermostat or a shorted out defrost heater if you have a frost-free model. With standard refrigerators, the ice build-up tells you it's time to ease the compressor load by manually defrosting the fridge.
A worn-out door gasket or a sagging freezer or food compartment door may allow warm air into the refrigerator. In the worst case scenario, the compressor will keep on running in order to cool the invading air. Open each door in turn and lift it. If it moves, the hinge bolts have worked loose. Adjust the door and tighten the bolts to correct this problem. Inspect the door seals periodically to see if they have cracked or flattened excessively and take the time to fit a suitable replacement when necessary.
Incandescent refrigerator light bulbs radiate a surprising amount of heat. If the light stays on when the door is closed, the hot bulb raises the interior temperature and overworks the compressor. This not only causes it to run constantly, but also shortens the compressor’s life. Open the food compartment door and press the light switch plunger inwards to see if the light goes out. If it remains lit, the switch is faulty and must be replaced.
If you eliminate all of the above possibilities and the compressor still keeps running for extended periods, your refrigerator may be low on refrigerant gas. In this case, schedule a service call from a qualified refrigerator technician as soon as possible.