An unexpected breakdown of household appliances always causes stress, especially when it comes to the refrigerator where food is stored. If you notice that the unit has stopped freezing, and a puddle has appeared on the back wall or floor, most likely the evaporator has failed. This element is the heart of the cooling system, and its damage requires immediate attention.
Replacing the evaporator in a refrigerator is a complex, but completely doable process for a person who has basic skills in handling tools and a soldering iron. In this article, we will analyze in detail how to diagnose the problem, prepare the workplace and replace the unit, giving the equipment a second life.
Before taking active steps, you need to clearly understand what kind of malfunction you are faced with. Often the symptoms can be similar to a broken thermostat or compressor, so competent diagnostics is the first and most important step. Erroneous replacement of serviceable parts will only lead to unnecessary financial costs and loss of time.
Signs of an evaporator malfunction
It is possible to determine that the heat exchanger is damaged by a number of characteristic symptoms that are almost impossible to ignore. The first sign is usually the lack of cold in one or both chambers, despite the fact that the compressor is running continuously. If you hear a characteristic gurgling or hissing sound, but the freezer remains warm, this is a sure sign of a refrigerant leak through a breakdown in the metal.
The second obvious sign is the presence of oily stains on the floor under the refrigerator or on the back wall inside the chamber. When the system depressurizes, compressor oil leaks out along with freon, which leaves sticky marks. Also, an uneven “coat” may form on the evaporator or, conversely, there may be a complete absence of frost when the engine is running.
It is worth paying attention to the operation of the compressor itself. If it turns on, works for a short period of time and turns off without picking up speed, or hums but does not start, the problem may lie in the lack of pressure in the circuit. Freon leak - this is not just a loss of cold, it is a risk of engine combustion due to lack of cooling and lubrication.
⚠️ Attention: If you smell burning or see sparking in the compressor area, immediately unplug the refrigerator. Further operation can lead to a fire or complete failure of expensive components.
To accurately confirm the diagnosis, technicians often use a soap solution, applying it to suspicious areas of the pipeline. The appearance of bubbles will indicate the location of the leak. However, in the case of a foamed evaporator, this method may not work, and then you have to rely on indirect signs and experience.
Selecting a new evaporator and preparing tools
Before starting work, you must purchase a suitable spare part. Evaporators come in different types: for the freezer, for the refrigerator compartment, aluminum or copper, “crying” or with the No Frost system. It is important to choose a part that matches the dimensions and mounting holes of your refrigerator model. Universal solutions exist, but they often require modification of the installation site.
In addition to the part itself, you will need a specialized tool. Without it, high-quality soldering and vacuuming of the system will not be possible. The minimum set includes a pipe cutter, a rolling machine, a solder torch and a pressure gauge station. If you do not have experience working with copper pipes, it is better to practice on scraps, since high-quality soldering is critical for tightness.
You will also need a cylinder with freon (usually R600a or R134a) and nitrogen to purge the system. Using the wrong refrigerant or incorrect charging proportions will lead to incorrect operation of the unit. Remember that working with gases under pressure requires caution and compliance with safety precautions.
Don't forget to prepare consumables: flux, solder, drying filters and pipe insulation. The filter drier must be changed whenever the circuit is opened, as it absorbs moisture from the air and loses its properties. You cannot save on this element, otherwise the moisture will freeze in the capillary and block the system.
Removing the old evaporator
The dismantling process begins with completely disconnecting the refrigerator from the power supply and defrosting it. Leave the doors open for at least 24 hours to allow all the ice to melt and moisture to evaporate. Working with wet components of the cooling system is strictly prohibited, as the water in the circuit will turn into an ice plug.
After defrosting, you must gain access to the evaporator. In refrigerators with a No Frost system, you will have to remove the plastic panel in the freezer by unscrewing the fastening screws and removing the air dampers. In models with a “crying” evaporator, it is often necessary to carefully separate the back wall of the chamber or, in difficult cases, partially cut out the polyurethane foam insulation.
The next stage is unsoldering the pipelines. Using a torch, heat the junction of the copper tube and the evaporator and carefully remove the solder. Be careful not to damage adjacent tubes or wiring. The old evaporator is removed from the niche, and it may be necessary to bend the fixing petals or cut off the fasteners.
☑️ Preparation for dismantling
If the evaporator is foamed in the housing, its removal requires special care. Often, craftsmen do not cut out the old heat exchanger completely, but cut the tubes and leave it in the body of the refrigerator, installing a new one on top or next to it. This allows you to maintain the integrity of the heat-insulating layer of the housing.
Technology for installing and soldering a new unit
Installation of a new evaporator begins with fitting. The part must fit tightly to the surface from which heat will be removed. To improve heat transfer, heat-conducting paste is often used or simply ensures maximum metal-to-metal contact. Fastening is carried out using standard holes or special clamps.
Soldering connections is the most crucial moment. The tubes must be cleaned, degreased and inserted into each other with a small gap. The joint is heated with a torch until it turns cherry red, after which solder is applied. It is important not to overheat the tube so that the solder does not leak inside, creating a blockage, or, conversely, not to underheat it, leaving a “cold” solder.
After soldering all connections, the system must be purged with nitrogen. This allows you to remove oxides formed during the heating process from the tubes and check the circuit for tightness under pressure. If the pressure drops, it means that somewhere there is a fistula that needs to be found and soldered again.
Why can’t you solder without nitrogen?
When soldering copper in air, an oxide film (scale) forms inside the pipe. Over time, these oxide flakes can break off and enter the capillary tube, causing a clog. Nitrogen purging displaces oxygen and prevents oxidation.
After a successful pressure test, a new filter drier is installed in the system. It is soldered last, quickly, so that it does not have time to absorb moisture from the air. At this point, the mechanical part of the replacement is considered complete, and you can proceed to charging with refrigerant.
Evacuation and charging with refrigerant
Evacuation is necessary to remove air and water vapor from the circuit. Moisture is the main enemy of the refrigeration system, since at low temperatures it freezes and blocks the flow of freon. Using a vacuum pump, a vacuum is created in the system, which boils away the residual moisture. The process should last at least 30-40 minutes.
Refilling is carried out strictly according to the weight indicated on the nameplate of the refrigerator (usually located inside the chamber or on the back wall). You can use the illustrator peephole to determine the amount of freon only as an auxiliary method, but the main control is electronic scales. Overfilling or underfilling will lead to incorrect operation.
Different types of freons have their own nuances. For example, isobutane (R600a) is a fire hazard, so all work should be carried out in a well-ventilated area, away from open flames. Freon R134a is less dangerous, but also requires careful handling. After refueling, the process pipe is sealed.
| Freon type | Characteristics | Oil | Features |
|---|---|---|---|
| R134a | Odorless, non-toxic | Synthetic (POE) | Requires thorough drying of the system |
| R600a | Colorless, explosive | Mineral (MO) | Low charge, high efficiency |
| R407c | Mixture of gases (quasi-isotropic) | Synthetic | Filling only in the liquid phase |
| R12 | Outdated, destroys ozone | Mineral | Found in old equipment |
After refueling, turn on the refrigerator and check its operation. The uniformity of cooling of the evaporator, the temperature in the chambers and the compressor operating cycle are assessed. If all parameters are normal, the repair can be considered complete.
Common mistakes during self-repair
One of the most common mistakes made by beginners is neglecting vacuuming. Self-taught craftsmen often simply bleed off the air with freon, believing that this is enough. This is a gross misconception: moisture remains in the system, which in a few weeks or months will lead to the formation of an ice plug and repeated repairs.
Another mistake is using the wrong solder or flux. Acidic fluxes are strictly prohibited as they cause corrosion of copper from the inside. You need to use only special fluxes for refrigeration equipment or acid-free compounds. It is also dangerous to overheat the soldering area, which can lead to deformation of the tubes or burning through the wall.
Do not ignore replacing the filter drier. An old filter, even if it looks intact, is already saturated with moisture and will not be able to perform its function. Installing a new part is an inexpensive insurance against future problems with the system.
⚠️ Attention: Refrigerator specifications and refrigerant requirements may vary depending on the year of manufacture and environmental regulations. Always check the technical documentation of the manufacturer of your specific model before starting work.
Repair cost: yourself or a specialist?
When deciding on repairs, many compare the cost of spare parts with the cost of calling a specialist. Replacing the evaporator yourself saves money on the work of a technician, but requires the purchase of expensive equipment (pump, station, burner) if it is not available. For a one-time repair, buying a tool may be more expensive than the services of a professional.
If you have a tool, then the main costs will fall on the purchase of an evaporator, freon and consumables. On average, components cost 30-40% of the cost of calling a specialist for work. However, it is worth considering the risks: an error when soldering or refueling can lead to combustion of the compressor, the cost of which is most of the price of a new refrigerator.
Professional repairs provide a guarantee for the work performed and the materials used. The master takes responsibility for the tightness and proper operation of the system. If you are not 100% confident in your abilities, it is better to entrust this complex operation to specialists.
Is it possible to restore an old evaporator by soldering?
Theoretically, you can find and solder a fistula in an aluminum evaporator using special welding or argon, but in practice this rarely gives a long-term result. Aluminum is difficult to solder, and corrosion often affects the tube in several places. It is more reliable and easier to replace the entire assembly with a new one.
How long does it take to replace the evaporator?
For an experienced technician, the process takes from 1.5 to 3 hours, including time for vacuuming. Self-repair without experience can take a whole day, especially if there are difficulties with access to the unit or soldering.
Why is the back wall of the refrigerator swollen?
This is a classic sign of corrosion of the foamed evaporator. Gases released during the oxidation reaction of aluminum and moisture expand the polyurethane foam. In such cases, replacing the evaporator is mandatory; installation of an external (“crying”) heat exchanger is often required.
Is it necessary to change the oil in the compressor when replacing the evaporator?
With the correct repair technology (nitrogen purging), the oil does not need to be changed. It circulates in a closed loop. An oil change is only required if the compressor has burned out or a large amount of moisture and acid has entered the system.
What is the warranty period for a new evaporator?
The factory warranty on the part itself is usually 6-12 months, but only subject to professional installation. For self-repair, the warranty is provided by the store only for the absence of manufacturing defects at the time of purchase.