Users of household appliances often come across the term “cooler” when it comes to breakdown or maintenance of the unit. Many people mistakenly believe that this is a separate part that can be simply replaced, but in reality cooler it is a complex system that provides direct cooling of the chambers. Understanding the principle of its operation helps to quickly diagnose problems, such as insufficient cold or the formation of an ice crust.
In professional terminology, this unit is often called evaporator, and it is responsible for absorbing heat from the interior of the chamber. Heat exchange occurs due to the circulation of the refrigerant, which changes its state of aggregation. If you notice that food has begun to deteriorate faster or a strange coating has appeared on the walls, the problem may lie precisely in the malfunction of this circuit.
There are several types of designs, and this determines how often you will have to defrost the device. Modern models with the No Frost system are more complex than classic “crying” refrigerators, but the principle remains the same. Let's figure out what this unit consists of and why it fails.
Principle of operation and physics of the process
The main task of the evaporator is to extract thermal energy from the air of the refrigerator or freezer. The process is based on a physical law: during evaporation (transition from a liquid to a gaseous state), any substance absorbs heat from the environment. As a working fluid in household refrigerators, special gases are used - refrigerantssuch as R600a or R134a.
Liquid freon under high pressure enters thin evaporator tubes. Once in a low pressure zone, it boils at very low temperatures, actively absorbing the heat of the walls and air. After this, the compressor pumps out the gaseous refrigerant, compresses it, and the cycle repeats again in the condenser.
⚠️ Attention: An attempt to independently replace the refrigerant or solder the evaporator tubes without a vacuum pump and scales will lead to irreversible damage to the compressor and contamination of the system.
Efficiency heat transfer directly depends on the surface area with which the air comes into contact. This is why evaporator tubes often have a finned structure or are distributed over a large area of the back wall. Impaired air circulation around these elements, for example, due to dense packing of food, reduces system efficiency.
It is important to understand that the cooler does not “create” cold, it only transfers heat from the inside to the outside. If the door remains open for a long time, heat inflows increase, and the system may not cope, which will lead to an increase in the temperature inside the chambers.
Types of evaporators in modern refrigerators
The design of the cooler depends on the type of defrosting system installed in the refrigerator. There are three main types, each of which has its own characteristics of operation and maintenance.
- ❄️ Open evaporator: typical for older models and chest freezers. It is a coil that is in direct contact with the products or is freely accessible inside the chamber.
- ❄️ Foamed (hidden) evaporator: the tubes are mounted in the back wall of the fridge compartment and filled with polyurethane foam. Visually invisible, defrosting occurs automatically when the compressor is turned off (“crying wall”).
- ❄️ Evaporator of the No Frost system: located behind a plastic panel in the freezer (less often - in the refrigerator). It has a fan for forced air circulation and a heating element for periodic defrosting.
The most difficult to maintain is the foamed version. If it leaks freon due to corrosion, repairs often require installing an external cooling circuit, since opening the housing is not economically feasible. In models No Frost the main problem is freezing of air ducts.
The choice of cooler type affects energy consumption and humidity inside the chambers. Open systems retain moisture better, but require manual defrosting. Hidden and air systems are more convenient to use, but can dry out products if they are not packaged.
No Frost evaporator device
The “No Frost” system radically changes the approach to cooling. Here the cooler is located in a separate compartment, usually at the top of the freezer or behind the back panel. Air is driven through it using a fan and distributed through the channels.
The key element of such a system is not only the heat exchanger itself, but also its defrosting system. Since moisture from food settles on the cold fins of the evaporator in the form of frost, it must be thawed periodically. This process is carried out by temperature sensors and a timer (or electronic control module). (freezer only) Defrost heating elements, temperature sensors and timer (or electronic control module).
Air circulation is provided by a turbine, which forces a cold flow into the chambers. If the fan stops due to icing or motor failure, the evaporator stops producing cold, although the compressor itself may work properly. As a result, the products in the chamber begin to deteriorate, and a “fur coat” grows on the evaporator.
Why is ice not visible in No Frost?
Unlike older models, in the No Frost system ice builds up on a hidden evaporator behind a plastic wall. The user sees only the result - poor cooling or puddles under the refrigerator when the ice melts when the defrost breaks down.
Main faults and symptoms
Diagnosis of problems with the cooler often begins with a visual inspection and analysis of temperature conditions. There are a number of signs indicating that heat exchange is disrupted or the system is not working correctly.
The most common problem is insufficient cooling. The compressor hums almost non-stop, trying to gain temperature, but there is no desired effect. This may indicate a refrigerant leak, a clogged capillary tube, or a fan malfunction in the No Frost system.
Excessive icing is the second most common symptom. If you see that the back wall of the refrigerator compartment is covered with a thick layer of ice or snow, and the freezer door is difficult to close due to ice, then the defrost cycle is broken. In models with a “crying wall”, this may be due to a loose fit of the door, and in No Frost - with burnout of the heating element.
| Symptom | Probable cause | Affected node |
|---|---|---|
| The refrigerator does not freeze, the compressor is hot | Freon leak or blockage | Circulation circuit |
| Strong ice on the back wall | Faulty sensor or heating element | Defrost system |
| Noise and humming, no cold | Fan stop | Air duct / Turbine |
| Water on the floor under the refrigerator | Clogged drainage channel | Drain hole |
You should also pay attention to extraneous sounds. Gurgling or hissing may indicate movement of a mixture of gas and liquid in the tubes, which is often normal, but in combination with other symptoms requires attention.
Problems with freezing and drainage
Evaporator freezing is a natural process, but only if it is controlled by the defrost system. Moisture in the air condenses on cold surfaces and freezes. In a working refrigerator, this ice periodically melts and water flows into the drainage hole.
If the drainage becomes clogged with crumbs, mucus or ice plug, water begins to accumulate at the bottom of the chamber or flow out. In systems No Frost an ice plug can form in the water drainage channel itself, which will lead to melt water freezing around the heater and disabling it.
Frequent voltage fluctuations can cause the defrost timer to malfunction. If the defrost cycle does not start on time, the ice will completely block the airflow (air flow), and the refrigerator will stop cooling, even if the compressor is working.
Diagnostics and repair methods
Before calling a technician, you can carry out an initial diagnosis. Make sure the refrigerator is level, the doors close tightly, and there is enough space between the back wall and the furniture for ventilation. Often the problem lies in a banal violation of operating rules.
To check the defrosting system in No Frost models, it is necessary to dismantle the back panel of the freezer. Visually assess the amount of frost on the evaporator. If the “coat” is uniform and thick, the defrosting system does not work. If there is ice in only one place or there is none at all, but there is no cold, the problem may be a leak.
☑️ Primary diagnostics of the refrigerator
Professional diagnostics include checking the pressure in the system, searching for leaks using a leak detector and “testing” electrical circuits multimeter. Replacing the evaporator is a labor-intensive process that requires completely evacuating the system and charging the exact amount of refrigerant.
⚠️ Attention: Specifications and location of components may vary depending on the brand and year of manufacture. Always check the technical documentation of a specific model before starting disassembly.
Prevention and service life
The average service life of the evaporator is comparable to the service life of the refrigerator itself, if no mechanical damage or corrosion occurs. However, improper operation can shorten this period significantly.
The main enemy of the heat exchanger is moisture and aggressive environments. Do not place hot foods in the chamber as this will create excess humidity. Clean interior surfaces regularly and keep drainage clean. In models with an open evaporator (chest freezers), it is important not to damage the thin aluminum tubes when loading products.
Timely defrosting (for drip systems) and monitoring the condition of the door seals will help maintain optimal operation. Remember that corrosion of aluminum evaporator tubes due to contact with salt or acids (for example, from spilled brine) is irreversible and requires expensive repairs.
Is it possible to operate a refrigerator if the evaporator is covered with ice?
Operation is possible, but ineffective. A thick layer of ice acts as a heat insulator, preventing heat transfer. The compressor will wear out, trying to compensate for the loss of efficiency, which will lead to its overheating and increased energy consumption.
Why does the refrigerator take a long time to get cold after defrosting?
This is normal. After complete defrosting, the walls and food need time to cool. Depending on the load on the cameras, this process can take from 4 to 12 hours. Do not load a lot of warm products at the same time.
What is the danger of freon leakage from the evaporator?
Modern refrigerants (isobutane) are explosive in high concentrations, so if you smell gas, you need to ventilate the room. They are low-toxic for humans, but the absence of freon leads to food spoilage and compressor burnout.
How often do you need to defrost a refrigerator with a drip system?
It is recommended to carry out complete defrosting at least twice a year, even if the system is “crying”. This is necessary for hygiene, cleaning the drainage and checking the condition of the seals, which lose elasticity over time.