The situation when cold suddenly stops forming in the main chamber of the refrigerator, and food begins to spoil, always catches taken by surprise. Often, owners notice the problem too late, when the frost on the walls has already disappeared or, conversely, a whole “fur coat” has grown, and the temperature has approached room temperature. In most two-chamber models, it is the upper compartment that is the main evaporator, and malfunctions in its operation indicate critical disturbances in the refrigerant circulation system.
Before calling a technician or looking for a service center, it is necessary to carry out an initial diagnosis in order to understand the scale of the disaster. Malfunction it can lie in either a banal sensor sticking or a serious one freon leak requiring professional attention. Understanding the principles of operation refrigeration circuit will help you more accurately describe the symptoms to a specialist or, perhaps, fix the problem yourself if the problem is electrical.
It is important to note that modern systems No Frost i static models (“crying” evaporator) have fundamentally different cooling schemes, although the symptoms of breakdowns are often similar. In the first case, the cold is pumped by a fan, in the second it circulates naturally. If the top compartment is not cooling, but the bottom compartment (freezer) is working normally, this narrows the search to a defrost or air distribution system.
⚠️ Attention: If you hear a loud bang or smell burning wiring immediately after the refrigerator stops freezing, immediately unplug the appliance. Further operation may lead to fire or failure of the compressor.
Main reasons for the lack of cold in the upper compartment
The most common reason that upper chamber stopped cooling is a violation of the refrigerant circulation. In systems with one compressor, freon first passes through the freezer, cooling it, and only then enters the main compartment. If a plug has formed in the system or a leak has occurred, there is not enough pressure to “push” the freon to the top, and it has time to evaporate while still in the freezer.
Another common culprit is thermostat (thermostat). This device is responsible for turning the compressor on and off, based on the temperature in the chamber. If its sensing element fails or is displaced, the compressor may simply not start, believing that there is cold inside. In models with electronic control, this is responsible temperature sensor, which is also prone to oxidation of contacts.
- 🔧 Clogged capillary tube: the microscopic hole in the tube becomes clogged with oil breakdown products or moisture, blocking the freon current.
- ❄️ Malfunction of the defrost system: the evaporator becomes overgrown with ice, blocking the channels for the passage of cold air (relevant for No Frost).
- 🔌 Problems with the starting relay: the compressor hums, but does not start, or starts for a few seconds and stalls.
⚠️ Attention: In models with an inverter compressor, diagnosing the starting relay is not relevant, since it uses a different starting principle. Trying to replace the standard relay on the inverter will cause the electronics to burn out.
Diagnostics of the defrost system (for No Frost models)
If your refrigerator is equipped with a system No Frost, then the absence of cold at the top when the freezer is running by 90% indicates problems with evaporator defrost. Ice that accumulates on the radiator during operation must be regularly melted by heating elements. If this process is disrupted, the ice crust grows to such a thickness that it blocks the air channels, and the fan simply cannot drive cold air into the upper chamber.
The first step in diagnosis is checking the defrost heating element i sensor defrost. The heating element may burn out, and the sensor may “lie” to the controller about the temperature, which is why the heater will not turn on on time. Also, the defrost timer or the electronic control module often fails because it simply does not send a command to defrost at the right time.
To check the integrity of the heating element and sensors, you need to “ring” them with a multimeter for resistance. The normal resistance of the heating element is usually from 200 to 400 Ohms, depending on the power of the model. If the device shows a break (one on the screen), the element requires replacement.
☑️ Checking the No Frost system
It is also worth paying attention to fan. If it is frozen in an ice crust or its windings are burned out, air circulation will become impossible even if the evaporator is properly cooled. Sometimes it is enough to simply defrost the unit for a day so that the ice melts and the system starts working, but this is only a temporary measure if the cause of the breakdown has not been eliminated.
How to check the fan without disassembling?
Turn on the refrigerator and listen. If you hear the hum of the compressor, but there is no characteristic noise of the fan operating inside the chamber (usually heard as a quiet whistle or hum), it may be blocked by ice. Try gently knocking on the back wall of the chamber (where the evaporator is usually located) - if the fan starts, then the problem is ice freezing on its blades.
Problems with the compressor and start relay
The compressor is the “heart” of the refrigerator, creating pressure for the movement of freon. If compressor he buzzes but does not start, or starts and immediately clicks, the problem is most likely in the start relay or motor windings. A relay is a small plastic block that fits onto the compressor contacts. Over time, the contacts in it burn out, and it stops providing the necessary impulse to start.
In the case when the compressor operates continuously without turning off, but there is no cold in the upper chamber, this may indicate a loss of performance. The piston group may have worn out, and the compressor simply does not “pull” the pressure necessary to circulate the refrigerant throughout the circuit. In such cases, replacing the relay will not help - you need to replace the unit itself.
| Symptom | Probable cause | Action |
|---|---|---|
| Humming, clicking, silence | Faulty starter relay | Replacing the relay |
| Works constantly, does not cool | Compressor wear / Leakage | Pressure diagnostics |
| Extreme heating of the housing | Overload / Winding breakdown | Emergency shutdown |
It is important to check the temperature of the housing of the operating compressor. If it is heated to the point where it cannot be touched, this may indicate an interturn short circuit or dry operation due to the lack of freon. Thermal protection in such cases should turn off the engine, but if it is also faulty, the risk of fire increases.
Freon leakage and blockages system
If the compressor runs quietly and evenly, but there is no cold anywhere (or only in the freezer), there is a high probability of refrigerant leakage. Freon can escape through microcracks in the foamed part of the body (internal circuit) or through soldering joints of tubes if there has been corrosion. It is difficult to visually determine a leak, since freon is colorless and odorless, and there may be no oil stains.
Another option is clogged capillary tube. This is the thinnest copper tube where freon is throttled. If there is moisture or oxidation products in the system, they can clog the passage. A characteristic sign of a blockage is a hot condenser (grid at the back) and a cold compressor, or vice versa, local overheating at the site of the blockage.
⚠️ Attention: Self-filling with freon or attempting to clean the capillary without a vacuum pump and a pressure gauge station is impossible and dangerous. These works require a license and special equipment.
Faults in electronics and sensors
In modern models of refrigerators, such as Liebherr, Bosch or Samsung, the entire process is monitored by an electronic control module. If module receives incorrect data from the sensors, it may not turn on the compressor or fan. Often the temperature sensor itself, located in the air duct or on the evaporator, fails.
Oxidation of contacts in connectors is another common problem, especially in conditions of high humidity. Water may flow in during defrosting or due to a clogged drain hole, causing corrosion of the board or sensor contacts. A visual inspection of the board for blackened or swollen capacitors can answer the question of why the equipment does not respond to commands.
Sometimes a simple error reset (reset) helps. To do this, disconnect the refrigerator from the network for 15-20 minutes. If the problem was a software failure of the controller, after switching on the system may work normally. However, if the breakdown is physical, this method will only give a short-term effect.
When you need to call a technician
There are a number of situations when independent repair is not only useless, but also dangerous. If diagnostics indicate the need to open a sealed circuit, replace the compressor, or look for a leak in the sealed part of the housing, you cannot do without a specialist. These works require the use of nitrogen for purging, evacuation of the system and precise charging of refrigerant by weight.
A master is also needed if the evaporator in the foam part needs to be replaced. To do this, you often have to open the back wall of the refrigerator or cut off the foam layer, which is almost impossible to do neatly at home. Professionals use special tools and materials to restore thermal insulation.
Do not ignore warranty obligations. If your refrigerator is less than 3-5 years old (depending on the brand and component), any independent repair will void the warranty. In this case, the only correct solution is to contact an authorized service center.
Is it possible to operate the refrigerator if the upper chamber does not freeze?
Short-term operation is possible, but undesirable. If the problem is in the defrost system (No Frost), the ice will continue to accumulate, which can lead to fan failure or deformation of plastic parts. If the problem is a leak, the compressor will work hard trying to build up temperature, causing it to burn out. It is better to turn off the device until the reasons are determined.
How long should the upper chamber cool down after defrosting?
After complete defrosting (24 hours) and turning on, the refrigerator takes from 2 to 5 hours to reach an operating temperature of +2...+5°C. If after 5-6 hours of compressor operation the temperature in the upper chamber does not drop below +15°C, there is a malfunction.
Does the amount of products in the chamber affect the cooling rate?
Yes, it does. An empty refrigerator cools faster, but it also “holds” the cold worse when the door is opened. A workload of about 50-60% is considered optimal. However, if food blocks the ventilation holes (especially in No Frost systems), the cold will not circulate and the upper chamber will not cool.
Why, after replacing the compressor, does the refrigerator still not freeze?
There may be several reasons: poor evacuation of the system (moisture remains, causing an ice jam), incorrect dosage of freon, a malfunction of the thermostat (which does not give a command to operate) or a blockage in the filter-drier that they forgot to replace.