To prevent spoilage and bacterial growth, the optimum temperature for household refrigerator is approximately 34°F to 42°F. Professional walk-in refrigerators maintain a constant temperature of 35°F The temperature of household refrigerators is set by an internal thermostat, usually a wheel with numeric values. The wheel, which vaguely suggests warmer and cooler, does little to inform homeowners of the actual temperature. This system is okay until the milk freezes or the fridge seems to be getting a little warm. To test the internal temperature, purchase a refrigerator and freezer thermometer, or use an indoor outdoor weather station with a special sensor. Although the optimum temperature is below 40 F, it’s not uncommon for refrigerators to run as warm as 46 F.
To establish a baseline, set the refrigerator and freezer to the initial setting, usually right in the middle. Although the temperature controls are separate, all of the cold air is released from the freezer into the fridge. An overloaded freezer can prevent the cold air from reaching the fridge. Small changes like rearranging foods and removing items from the back of the freezer can make a big difference in the air circulation.
In American homes for less than a century, refrigeration is a fairy recent invention. Modern refrigerators work by compressing gases. Inside the compressor, gasses are put under extremely high pressure, which turns them into liquid. The liquid passes through a special valve into the non-pressurized section of the fridge called the evaporator. Evaporation reduces heat in the fridge, effectively cooling it. Think of a pot of boiling water, bubbling away and filling the room with steam. On the other hand, if the pot was empty and still on the burner it would be extremely hot, a lot hotter than boiling temperature. The body also uses evaporation to produce a cooling effect through sweat.
The ambient air also has can effect on the temperature fridges can maintain. In a cold area, like a basement the fridge may freeze unexpectedly. Likewise, in warm locations the fridge may struggle to keep foods cold enough. Problems with refrigerators keeping the correct temperature can be cause by mechanical mechanisms, such as timers and sensors, or something simple, like dust build-up or the seal. Before calling a repairman, remove the grill from the front and use a vacuum attachment to remove dust from the coils and air intake. On the back of the refrigerator, there is usually in air intake vent, which should resemble a chimney or a small tube. Make sure the opening is free from dust and lint. Always use a vacuum attachment, instead of an air blower to remove dust.
Problems with the refrigerator keeping a constant temperature can also be caused by the magnetic door seal. Clean the door seals and contact points using dish detergent. To see if the seal is worn out or damaged, close a dollar bill in the door. If it easily pulls out, it’s time replace the seal.
The evaporator is a very important part of the refrigeration system. The coils and cooling system are designed to work with a very specific amount of coolant. If the system looses any gas, it alters the pressure. Low coolant will cause the fridge to run constantly. It can also lead to ice build up on the evaporator coils, which inhibits cooling. The fridge may even seem cool due to the massive ice build up. Problems with ice can also be related to a faulty auto defrost system.