A decrease in cooling efficiency or complete cessation of operation of the refrigeration chamber often indicates problems with heat exchange equipment. It is evaporator responsible for absorbing heat from the internal space, turning liquid refrigerant into gas. When this unit fails, the temperature inside the chambers begins to rise, the products deteriorate, and an uncharacteristic ice shell may form on the walls.
Restoring the system's functionality is a process that requires accuracy and understanding of the physical processes occurring inside the circuit. It is not always necessary to call a specialist to solve a problem, since some problems, such as mechanical damage or blockages, can be eliminated yourself if you have basic tools. However, it is important to clearly understand the limits of your capabilities so as not to aggravate the situation with the refrigerant.
In this article we will analyze in detail the design of the unit, diagnostic methods and action algorithms for various types of breakdowns. You will learn how to correctly install defrost, replace a burnt heating element or solder an aluminum tube. A competent approach will extend the life of your Indesit, Atlant or Bosch without extra costs for service.
Operating principle and design of the evaporator
The evaporator is a radiator, usually made of aluminum tubes or steel plates through which it circulates refrigerant. During operation, liquid freon, passing through the capillary tube and entering the expansion zone of the evaporator, boils sharply at low pressure. This physical phenomenon is accompanied by the active absorption of thermal energy from the surrounding air of the refrigerator chambers.
Structurally, the element can be open, hidden in the walls of the case, or located in a separate No Frost block. In systems with automatic defrosting, heaters are attached to the radiator, which are periodically turned on to thaw frozen ice. This process is controlled by a timer or an electronic module that reads temperature sensors. Heating elements (heat), which are periodically turned on to thaw frozen ice. This process is controlled by a timer or an electronic module that reads temperature sensors.
Air circulation is provided by a fan, which drives the cooled masses through the air ducts into the fridge compartment. Malfunction of any of the components of this chain leads to an imbalance of temperatures. For example, if the fan is humming but not spinning, cold will not flow to the food, although the evaporator itself may be icy.
⚠️ Attention: Aluminum evaporator tubes are extremely sensitive to mechanical stress. One careless movement with a knife when trying to pry off the ice can lead to depressurization of the circuit and leakage of freon.
Why aluminum?
Aluminum has high thermal conductivity, which makes it an ideal material for heat exchangers. However, its softness requires care when cleaning and maintaining it. Steel evaporators are less common and usually in older models of refrigerators.
Main signs of a heat exchanger malfunction
Diagnostics begins with a visual inspection and analysis of the behavior of the equipment. The first sign is often the appearance of a “coat” - a layer of ice that does not disappear after regular defrosting. If you notice that the refrigerator is running non-stop, trying to gain temperature, this indicates low heat transfer efficiency.
Other symptoms include the appearance of puddles under the device or inside the chambers. This indicates that the melt water drainage system is not coping, possibly due to freezing of the drainage channel, which runs in close proximity to evaporator. You should also be alert to the specific chemical smell that appears when freon leaks from a leaky tube.
- ❄️ A thick layer of frost or ice forms on the back wall of the refrigerator compartment.
- 🌡️ The temperature in the chamber is higher than the set one, despite the continuous operation of the compressor.
- 💧 Water accumulates under the refrigerator or at the bottom of the chamber.
- 🔊 The compressor operates with increased noise or does not turn off for a long time.
It is important to distinguish between problems with the evaporator and thermostat malfunctions. If the compressor does not respond when the temperature on the regulator drops, the problem is most likely in the sensors. If it hums, but there is no cold, we check the cooling system.
Necessary tools and preparation for repair
Before you start disassembling the unit, you need to prepare a workplace and tools. To access the evaporator on most models, you will need to remove the back panel of the freezer or the entire interior trim. You will need a set of screwdrivers, including Phillips and flathead screwdrivers of different sizes, as well as a spatula for carefully removing the plastic.
If you plan to replace the heating element or repair tubes, the list of tools expands. To work with electrical components, you need a multimeter to check resistance. To restore the tightness of the circuit, you will need a torch, solder and flux, although at home, cold welding or epoxy compounds are more often used for a temporary solution.
Be sure to provide good lighting to the work area. Refrigerator innards are often hidden deep within the cabinet, and without a flashlight you can damage fragile plastic latches or wiring. Also prepare a container to collect water that will remain in the drainage system after defrosting.
☑️ Preparation for repair
Do not forget to completely defrost the refrigerator before starting work. Trying to remove a plastic panel that is frozen to the ice is guaranteed to break the fasteners. Leave the device turned off for at least 12 hours, preferably a day, so that all the ice inside turns into water.
Diagnostics and replacement of the defrost heating element
One of the most common reasons for the formation of an ice lump on the evaporator is the failure of the defrost heater. In systems No Frost the heating element is located directly under the aluminum radiator. To check its integrity, you need to get to the heater contacts, having first removed the protective casing.
The test is carried out using a multimeter in resistance measurement mode. The normal resistance of a working heating element is usually from 200 to 500 Ohms. If the device shows one or infinity, it means that the filament is broken and parts are required. Visually, swelling or ruptures of the housing may be visible on a faulty heating element. replacement details. Visually, swelling or ruptures of the housing may be visible on a faulty heating element.
| Parameter | Normal | Fault |
|---|---|---|
| Resistance | 200-500 Ohm | Infinity (break) |
| Appearance | Smooth surface | Blisters, cracks |
| Insulation integrity | No damage | Burnt wires |
When replacing, it is important to install the new element correctly. It must fit tightly to the surface of the evaporator or fit into the designated grooves. Poor contact will result in heat escaping into the air rather than melting the ice on the tubes. Also check the condition of the thermal fuse, which is often paired with a heating element and burns out when overheated.
⚠️ Attention: When installing a new heating element, make sure that its power and geometric dimensions fully correspond to the original part. Using analogues with other characteristics can lead to melting of the plastic parts of the case.
Elimination of mechanical damage to tubes
Mechanical damage to aluminum tubes is a serious problem that often arises from inaccurate defrosting with sharp objects. If you hear a hissing sound or smell oil, it means that the circuit has depressurized and escaped freon. Repair in this case requires restoring the tightness and then refilling the system.
To eliminate a fistula at home, you can use the soldering method with a special solder for aluminum or use two-component cold welding. Before applying the composition, the surface must be thoroughly cleaned and degreased. Cold welding is a temporary solution and is suitable for small holes, but does not withstand high pressure in the long term.
A more reliable method is to install a copper patch. To do this, the damaged area is cleaned, tinned, and a piece of copper foil or tube is soldered using active flux. After drying and checking the tightness, it is necessary to evacuate the system and charge it with new refrigerant, which requires specialized equipment.
If the damage is in a hard-to-reach place, for example, foamed in the housing, repair may not be practical. In such cases, craftsmen often recommend installing an external mounted evaporator, although this reduces the aesthetics and useful volume of the chamber. The decision depends on the cost of new equipment and the price of spare parts.
Assembling the system and checking operation
After replacing faulty elements or restoring tightness, it is necessary to properly assemble the unit. All removed panels must fit into place without gaps, and the mounting screws must be tightened until the end. Pay special attention to the installation of the fan: it should rotate freely, without touching the ice or structural elements with its blades.
Before connecting to the network, make sure that all electrical contacts are securely connected and insulated. Check that the wires are not pinched by sharp metal or plastic edges. Only after visual inspection can you plug into the socket and start the compressor.
The first cycle of operation may take several hours. At this time, do not open the refrigerator doors so that it can reach the required temperature. Listen to the sounds of operation: there should be no gurgling (a sign of air in the system) or knocking. If after 5-6 hours cold has established itself in the chamber, and uniform frost has formed on the evaporator (in models without No Frost) or is not there (in No Frost), the repair can be considered successful.
- 🔍 Visually inspect the assembled structure for unnecessary parts.
- 🔌 Check the reliability of the electrical connectors.
- ⏱️ Let the refrigerator operate for 6-8 hours without loading food.
- 🌡️ Monitor the temperature with a thermometer placed in the center of the chamber.
⚠️ Attention: Technical characteristics and layout of components may vary depending on the model and year of manufacture. Always check the manufacturer's official documentation for your specific device.
Frequently asked questions (FAQ)
Is it possible to operate a refrigerator if the evaporator is covered with ice?
Long-term operation in this mode is strictly not recommended. The thick layer of ice acts as a thermal insulator, causing the compressor to run nonstop in an attempt to cool the chamber. This leads to overheating of the motor, increased power consumption and eventual failure of the unit.
How often do you need to defrost a refrigerator with the No Frost system?
The system No Frost assumes automatic defrosting of the evaporator. However, once every 6-12 months, it is recommended to completely defrost and wash the refrigerator to remove bacteria and check the drainage holes, even if there is no visible ice.
Why does ice freeze again after a week after replacing the heating element?
The cause may be a malfunction of the defrost timer, defrost sensor or thermostat. It is also possible that the new heating element is installed incorrectly and does not warm up the entire surface of the radiator, or the drainage hole is clogged with debris, and the water does not have time to drain, freezing back.
What is the danger of freon leakage for humans?
Modern refrigerants (isobutane, freons) in small quantities contained in household refrigerator, are not toxic to humans after short-term inhalation in a ventilated area. However, they displace oxygen, so in a confined space a large leak can cause suffocation. The main risk is the fire hazard of certain gases and environmental harm.