A decrease in cooling efficiency or complete loss of cold in the refrigerator compartment often indicates critical problems in the refrigerant circulation system. Evaporator is the heart of this process, absorbing heat from the internal volume of the chamber. If this unit fails, the products begin to deteriorate, and ice or, conversely, moisture may appear on the walls.
Before proceeding with complex manipulations, it is necessary to carry out an initial diagnosis. Users often confuse failure thermostat with a freon leak or a clogged capillary tube. In this article we will look at how to identify the true cause of the malfunction and whether it is possible to carry out evaporator repair at home without specialized equipment.
It is worth understanding that working with the refrigeration circuit requires increased caution and adherence to technique safety. Damage to aluminum evaporator tubes due to inaccurate defrosting with a knife is the most common cause of refrigerator failure. If you are not confident in your abilities, it is better to turn to professionals, since improper sealing can lead to repeated failure in a short time.
Principle of operation and evaporator device
The evaporator is a heat exchanger in which liquid refrigerant boils at low pressure, turning into gas and absorbing thermal energy. In modern models No Frost it is hidden behind a plastic panel on the back wall of the freezer. In older models with a weeping evaporator, it can be built directly into the wall or made in the form of a coil.
Structurally, this is a system of thin tubes, often aluminum, with soldered plates to increase the heat transfer area. Tightness this system is a key operating condition. Even a microscopic hole will allow gas to escape and moisture to enter, which will cause corrosion and the formation of acids that corrode the compressor from the inside.
It is important to distinguish between the types of heat removal systems. In static refrigerators, natural convection is used, and in systems No Frost a fan is responsible for air circulation. A malfunction of any element of this chain - from the defrost heating element to the temperature sensor - can simulate a breakdown of the evaporator itself.
⚠️ Attention: Aluminum, from which modern evaporators are most often made, is extremely difficult to solder at home. This requires special fluxes and skills. An attempt to solder the hole with ordinary tin will lead to instant depressurization.
Main signs of a heat exchanger malfunction
You can determine that the problem lies in the cooling circuit by a number of indirect signs. The first sign is often that the compressor is not working correctly. It can turn on for a short time and turn off, or, conversely, work non-stop, but do not produce cold.
Visual inspection also provides a lot of information. If you notice swelling in the back wall of the refrigerator compartment or the appearance of oily spots under the unit, this indicates depressurization. The oil flows out along with freon through the hole formed.
- 🧊 A “coat” of ice of uneven thickness has appeared on the back wall of the freezer, which indicates a violation of freon circulation.
- 📉 The temperature in the chambers is higher than the established norm, food quickly spoils or defrosts.
- 🔊 The compressor works intermittently, often clicks the relay or hums, but does not start.
- 💧 The appearance of water on the floor around the refrigerator if the condensate drainage system is blocked by ice due to a defrost failure.
Another important symptom is the smell. When the compressor windings burn out or there is a strong leak, a specific chemical odor may appear. However, most often a freon leak has no odor, since modern refrigerants are odorless.
Diagnostics: leak detection and leak testing
To accurately determine the location of the leak, technicians use leak detectors or the nitrogen pressure test method. At home, you can use a soap solution, but it is effective only if there is residual pressure in the system. If all the freon has come out, this method will not work.
You must carefully remove the back panel of the freezer (in models No Frost). Inspect the evaporator in good light. Look for signs of corrosion, blistering paint, or obvious holes. Often cracks form in places where tubes are bent or near fasteners.
If the defect cannot be visually found, a more in-depth diagnosis will be required. Vacuuming the system will help determine whether it holds pressure. For this you need a vacuum pump and a pressure gauge station.
Why can’t you use oxygen for pressure testing?
Oxygen mixed with oil and freon forms an explosive mixture that explodes at the slightest spark from the compressor. To check for leaks, use only dry nitrogen or a proven low-pressure refrigerant.
| Symptom | Probable cause | Test method |
|---|---|---|
| The refrigerator does not freeze | Leakage freon | Checking the pressure with a pressure gauge |
| Ice only at the inlet of the tubes | Clogged capillary tube | Warming up the filter drier |
| The compressor is hot | Motor malfunction | Current clamp measurement |
| Frost all over the evaporator | Defrost system malfunction | Telephone and timer dialing |
You cannot draw conclusions based on only one criterion. For example, the lack of cold can be caused not only by a leak, but also by a breakdown of thermostatwhich simply does not give the command to start the compressor.
Preparation for repair and necessary tools
Evaporator repair is labor-intensive a process that requires specific tools. You will need not only a standard set of screwdrivers, but also equipment for working with the refrigeration circuit. Without it, high-quality repairs are impossible.
Before starting work, the refrigerator must be completely defrosted (at least 24 hours) and disconnected from the network. This is critical for safety and for removing moisture from hard to reach areas. Any water inside the system will turn into an ice plug when freezing.
- 🛠️ Gas (propane-butane) or oxygen burner for soldering copper and aluminum compounds.
- 🔩 A set of keys, pliers, wire cutters and a knife for stripping insulation.
- 🧪 Solder (silver PSr40 or copper-phosphorus) and flux (borax or specialized flux for aluminum).
- 📏 Manometric manifold and vacuum pump for filling and pumping out the system.
You will also need a new filter-drier, since the old one will When the circuit is opened, it becomes saturated with moisture and ceases to perform its function. Its replacement is mandatory for any intervention in the sealed circuit.
☑️ Preparation for repair
Technology for replacing and soldering the evaporator
If a decision is made replacement, the old evaporator is carefully removed. In models where it is foamed into the wall, it is sometimes easier to install an external (“crying”) evaporator than to cut out the old one. It is less aesthetically pleasing, but functionally effective and easier to perform.
The soldering process requires skill. Copper is easy to solder, but with aluminum you will have to tinker. The surface is cleaned to a shine, degreased and coated with flux. It is necessary to heat evenly so as not to burn through the thin wall of the tube.
After installing the new unit, the circuit is assembled. Filter drier installed last before vacuuming. It is important to observe the direction of flow indicated by the arrow on the filter housing.
⚠️ Attention: When soldering, use asbestos cloth or damp rags to protect plastic parts and insulate wires from melting. An open flame near polyurethane foam is dangerous!
Next comes the most important stage - vacuuming. The pump should run for at least 30-40 minutes to remove all moisture and air from the system. The residual pressure should be close to zero. Only after this can you open the freon valve.
Refilling with refrigerant and checking operation
Refilling is carried out strictly according to the weight indicated on the technical plate of the refrigerator (usually on the inner wall or back). Using cylinders without scales is unacceptable, since excess or lack of freon will lead to incorrect operation.
Refilling process:
- Connect the cylinder with freon to the service fitting.
- Open the valve and start the compressor.
- Monitor current consumption and pressure on the pressure gauge.
- Solder the filling tube when the required amount of gas has been collected.
After refueling, leave the refrigerator to operate for several hours. Check the temperature in the chambers, defrost operation and the absence of extraneous noise. The condenser grille at the back should heat up evenly (about 2/3 of the height).
If the system works correctly, you can install decorative panels. However, during the first 24 hours, it is recommended to periodically check the unit for the appearance of oil or frost in the wrong places.
Frequently asked questions (FAQ)
Can a hole in the evaporator be sealed with cold welding?
Cold welding may be a temporary solution for a few days or weeks, but this is not a complete renovation. Under the influence of temperature changes and vibration, the tightness will be broken again. In addition, it is difficult to ensure adhesion to oil and aluminum.
How much does it cost to replace an evaporator from a specialist?
The cost consists of the price of the spare part (from 2,000 to 6,000 rubles depending on the model) and the cost of work (from 4,000 rubles). The total amount is often more than 50% of the cost of a new refrigerator, which makes repairs not always economically feasible.
Why did the refrigerator start to freeze worse after the repair?
Possible reasons: insufficient vacuuming (moisture remained), incorrect dosage of freon, use of a low-quality filter-drier or leaky soldering through which air is sucked in.
Is it necessary to change the compressor when replacing the evaporator?
The compressor is replaced only if it is faulty (interturn short circuit, wedge, low compression). If the motor is working properly and the system was thoroughly flushed with nitrogen during repairs, replacing the compressor is not required.