How to check the refrigerator evaporator: complete instructions

The appearance of warm air in the refrigerator compartment while the compressor is running often indicates problems in the cooling system. The central element of this process is evaporatorhidden behind the back wall or in a separate compartment. It is here that the refrigerant boils, turning into gas and actively removing heat from the internal volume of the chamber.

Before calling a technician or disassembling the unit, it is necessary to carry out an initial diagnosis. Evaporation unit it may stop cooling for various reasons: from a banal clogged capillary tube to more serious ones mechanical damage. Understanding how it works will help you save time and money.

In this article we will look in detail at how to safely get to the unit, what to look for during a visual inspection and what tools are needed to check the integrity of the system. You will learn how to distinguish simple ice from a serious breakdown.

Symptoms of a heat exchanger malfunction

The first sign that heat exchanger is not working correctly is the lack of cold when the motor-compressor is running. You may hear a characteristic buzzing or clicking sound, but the food in the chamber begins to deteriorate. In No Frost systems, this is also often accompanied by a complete lack of airflow.

The second alarm signal is the appearance of water at the bottom of the refrigerator compartment or under the vegetable boxes. If the drainage system is not clogged with debris, the cause may be excessive freezing of the evaporator, which does not have time to thaw. The water simply does not have time to go into the pan.

It is also worth paying attention to the nature of the sound of the compressor. If the unit turns on for a short time and immediately turns off, or, conversely, works without stopping, this may indicate problems with the circulation of freon. Cooling circuit may be partially or completely blocked.

⚠️ Attention: If you smell a strong burning smell or see sparking, immediately turn off the refrigerator from the mains. Further operation in this condition is strictly prohibited to avoid a fire.

Sometimes the malfunction appears visually through the rear wall. If it is covered with a “coat” of uneven ice or, conversely, is absolutely dry and warm when the compressor is running, this is a direct indication that it is broken. In the first case, the defrost sensor is often to blame, in the second - a leak or blockage. refrigerant circulation broken. In the first case, the defrost sensor is often to blame, in the second - a leak or blockage.

Preparation for diagnostics and disassembly

To carry out a quality check, you will need a minimum set of tools. Be sure to turn off the power to the unit before starting any work. Working with electrical components and wet environments requires safety precautions. You will need:

• 🔧 A set of screwdrivers (Phillips and flathead) for removing panels.
• 🔦 A powerful flashlight for inspecting hard-to-reach places.
• 🧤 Protective gloves to avoid cutting yourself on sharp metal edges.
• 📏 Hairdryer for accelerated defrosting (use with caution).

The process begins with completely defrosting the refrigerator. Even if you plan to use a hair dryer, natural defrosting for 10-12 hours is often more effective and safer for the plastic. After this, remove all shelves, drawers and fasteners that interfere with access to the back wall.

Carefully unscrew the screws securing the back panel. In some models Indesit or Atlant they may be hidden under decorative plugs. By removing the panel, you will gain access to the evaporator itself and the fan (in No Frost models). Do not use excessive force to avoid breaking the plastic latches.

Visual inspection and leak detection

Open access to the evaporator allows for a detailed visual inspection. Take a close look at the aluminum tubes and plates. There should be no oily stains on them. Oil often escapes along with freon through microcracks, so greasy marks are a sure sign of depressurization.

Pay attention to the color of the metal. If you see oxidation or rust at solder joints or pipe bends, this is a risk area. Corrosion can lead to the formation of fistulas through which the refrigerant slowly escapes into the atmosphere. Check the entry points of the tubes into the housing especially carefully.

In systems with an open evaporator (weeping type), it is important to check the condition of the drainage hole. It is located at the bottom of the heat exchanger. If it is clogged with ice or dirt, condensation will not drain, which will lead to the formation of an ice plug and disruption of heat transfer.

To search for leaks invisible to the eye, professionals use a soap solution. Apply it to suspicious areas and turn on the compressor (briefly). The appearance of bubbles will indicate where the gas is escaping. However, at home, this method may not be effective due to low pressure in the system.

Why can’t you use a knife to chip ice?

Using sharp objects to remove ice from the evaporator is the most common cause of punctured tubes. Aluminum is very soft, and even light pressure can lead to instant depressurization of the system and expensive repairs with replacement of the compressor.

Checking the defrost system (for No Frost)

In refrigerators with the system No Frost the proper functioning of the defrost heating element is critically important. If it burns out, the evaporator becomes overgrown with ice, which blocks the access of cold air to the chamber. You can check the heating element with a multimeter in continuity mode.

You also need to check the defrost sensor and timer (or electronic control module). The sensor must open the circuit when a certain temperature is reached. If it is “stuck”, the heating element may not turn on at all or heat constantly, which is equally harmful to the system.

Often the problem lies in banal freezing of the fan. The blades may hit the ice, causing the motor to hum but not turn. In this case, high-quality defrosting is sufficient. If the motor burns out, it will have to be replaced, since air circulation will stop completely.

Diagnostics of capillary tube blockages

One ​​of the most difficult problems to diagnose is clogged capillary tube. This is a thin copper channel through which freon enters the evaporator. If there is moisture or oil breakdown products in the system, they can turn into an ice or paraffin plug.

A symptom of such a blockage is often a cold condenser (grid at the back) and a hot compressor that operates with overload. In this case, the evaporator itself can be partially cold (only at the inlet) or completely warm. The pressure in the system drops to a vacuum.

It is difficult to check this at home, but you can try the following method: turn on the refrigerator and after 10-15 minutes gently touch the evaporator (not with your hands, but with the back of your hand, so as not to freeze). If it is cold only at the entrance of the tube, and then it is warm, there is a blockage.

Removing the blockage requires professional intervention: purging with nitrogen, replacing the filter-drier and evacuating the system. It is impossible and dangerous to perform these operations on your own without equipment.

When you need to call a technician

There are a number of situations when self-repair can lead to final breakdown of the unit. If you find a clear freon leak (oil stain, hissing), further attempts to start the compressor may burn its windings. Refrigerant circulates in the system along with oil, which lubricates the rubbing parts of the motor.

Also, do not bother replacing the compressor or soldering copper pipes without the appropriate experience and tools. Improper soldering will lead to the formation of oxides inside the system, which will quickly damage the new compressor. Evacuation is a mandatory step that cannot be skipped.

If after defrosting and checking the electrical circuit (heating element, sensors) the problem does not disappear, most likely the problem is in the mechanical part of the refrigeration circuit. This requires diagnostics with a pressure gauge station to measure suction and discharge pressure.

⚠️ Attention: Modern refrigerators use mixtures of refrigerants (for example, R600a), which are explosive when in contact with air in a certain concentration. Work with such systems should be carried out in a well-ventilated area.

It is also worth considering that some manufacturers foam the evaporator inside the housing. In such cases, replacing it is impossible without compromising the integrity of the thermal insulation, which often makes repairs economically impractical. It is better to clarify in advance the design of your cooling module.

Frequently asked questions (FAQ)

Is it possible to use a refrigerator if the evaporator is covered with ice?

It is not possible to operate the unit with an iced-up evaporator recommended. The ice acts as a heat insulator, forcing the compressor to run continuously, trying to build up the temperature. This leads to its overheating and premature failure, as well as to an increase in electricity bills.

How often do you need to defrost the refrigerator manually?

Refrigerators with manual defrosting (“crying” wall) require defrosting 1-2 times a year, when the ice layer reaches 3-5 mm. The systems No Frost do not need to be defrosted, since this process occurs automatically. The exception is emergency freezing due to a breakdown.

Why does the refrigerator not cool after defrosting?

If after complete defrosting (more than 24 hours) the cold does not appear, there may be a freon leak or blockage in the system. The thermostat or compressor start relay could also be faulty. Professional diagnostics are required.

What is the danger of a puncture of the evaporator?

A puncture of the evaporator leads to the instant release of all the refrigerant and the entry of moisture and air into the system. Moisture reacts with oil and freon, forming acid, which corrodes the compressor windings from the inside. Repair in this case is difficult and expensive.

Is it possible to restore the evaporator if it has leaked?

Aluminum evaporators are extremely difficult to solder at home. Usually they are either replaced with new ones (mounted) or an external evaporator (“dovetail”) is installed inside the chamber. Welding a hole with solder without a special flux for aluminum is a temporary and unreliable solution.