The majority of residential refrigerators have their evaporators located against the back walls of their freezers. These evaporators consist of coils, which absorb heat, and fans, which circulate the resulting cool air.
In addition to circulating the air within freezers, evaporators use fans to send cool air into food storage lockers, or the fresh foods sections of refrigerators. While evaporators can cool air to freezing temperatures -- below 32 degrees Fahrenheit -- by the time that air travels to a fresh foods section it will be slightly warmer, which is why liquids, fruits and other food items don’t freeze when you put them in the fresh section of the fridge but do freezer when you put them in the freezer.
Freezer and Fresh Foods Section
As BestStuffcom points out, one of the problems with the standard placement of a refrigerator’s evaporator is that it does not provide fresh foods with enough humidity or moisture. In a freezer, any moisture present in the air will freeze to the evaporator as its coils suck away heat.
As a result, the air that the evaporator’s fan circulates into the fresh foods section will be dry. To increase humidity in the fresh foods section, some appliance manufacturers have started installing two evaporators in their refrigerators.
Per the standard, one powerful evaporator goes in the freezer for super-cooling air, while a second, less-powerful evaporator goes in the fresh foods section for providing slightly warmer air that retains more of its moisture content.
Attached to the Metering Device
Regardless of where an evaporator is located spatially, the component will always be connected to a metering device. In the majority of residential refrigerators, a metering device consists of a copper capillary tube, which is a tube with an incredibly tiny internal diameter.
The metering device is responsible for controlling the flow and pressure of refrigerant liquid as it travels from a refrigerator’s condenser to its evaporator.
Evaporators are some of the noisiest refrigerator components. If your fridge has become unbearably loud, the motor of the evaporator fan could be to blame and replacing it will likely be the best solution.
Another cause of noise is the evaporator coil, which will produce hissing sounds and steam during defrost cycles. However, this defrosting is a necessary “evil” and does not mean your evaporator is broken.