The situation when the refrigerator compartment is operating normally, but in the freezer compartment or, conversely, in the upper compartment the temperature ceases to drop to the required level values, is one of the most common malfunctions in the operation of household appliances. The user may notice that the products in the upper compartment begin to thaw, frost disappears on the walls, or, on the contrary, ice appears where it should not be. Primary diagnostics This is often confusing, since the compressor may continue to hum, creating the illusion of normal operation of the system.
It is important to understand that modern two-chamber units, be it Indesit, Atlant or Bosch, often use a single cooling system with forced air circulation or an evaporator located in the freezer. If the top is not cooling, it almost always indicates a problem with the refrigerant cycle or a problem with the heat removal system. Ignoring the problem at an early stage can lead to the complete loss of the compressor, the repair of which will cost much more.
In this article we will analyze in detail the mechanical and electrical causes of malfunctions, explain how to distinguish a simple blockage from a serious leak, and determine when you can cope on your own, and when you need to call a technician with specialized equipment.
The principle of operation of the No Frost system and static cooling
To understand the essence of the breakdown, you need to briefly consider the structure of your refrigerator. In models with No Frost the cold is generated in the evaporator, which is usually hidden behind the back wall of the freezer. A special fan forces cold air through the air ducts into the upper refrigerator compartment. If the top is not cooled, the problem often lies precisely in the disruption of the circulation of this air flow.
In units with a static (drip) type of defrosting, the evaporator can be located directly in the upper part or be combined. Here the cold sinks down naturally by convection. Violation of the tightness of the circuit or failure of the thermostat leads to the fact that the upper compartment ceases to perform its functions, while the bottom may remain cold due to inertia or operation of the compressor in emergency mode.
⚠️ Attention: An attempt to independently open the back panel in No Frost models without turning off the power and defrosting for 10-12 hours can lead to damage to plastic air ducts and the fan.
The key element here is evaporator. If an ice coat forms on its surface due to a malfunction of the defrost heating element, the air simply will not be able to pass through the radiator and enter the chamber. As a result, the compressor works non-stop, trying to cool the sensors, but physically cannot transfer the cold into the chamber volume.
Mechanical damage and refrigerant leakage
One of the most serious reasons why the upper chamber stops cooling is depressurization of the system. The refrigerant (freon) circulates in a closed circuit under pressure. If a hole is formed in the tubes, the gas escapes and cooling efficiency decreases. This often happens due to metal corrosion or mechanical damage due to careless defrosting with a knife.
Leakage symptoms appear gradually. First, the refrigerator starts to work longer to gain temperature. Then the compressor may stop turning off altogether, working non-stop. At the same time, the freezer can still remain cold, but the upper compartment is already warm. In advanced cases, the characteristic heating on the rear grille of the condenser (radiator) disappears.
How does a technician determine a leak?
The technician uses a leak detector - a device that reacts to freon vapor, or pressurizes the system with nitrogen under high pressure to find the location of the gas outlet by the drop of the pressure gauge needle.
It is important to note that sealing tubes and filling with freon is not just “adding gas”. It is necessary to find the location of the leak, eliminate it and replace the filter-drier, which could be saturated with moisture from the air. Without evacuation of the system, a new portion of refrigerant will quickly become unusable.
Faults of the compressor and start relay
The compressor is the heart of the refrigeration unit. If it does not create enough pressure, the refrigerant will not be able to circulate through the system and the cold will not reach the upper chamber. Often the problem lies not in the motor itself, but in start-protective relay. This small element is responsible for starting the engine and protecting against overloads.
If the relay is “stuck” or burnt out, the compressor will either not start at all, making only clicks, or will work jerkily. In some cases, when the piston group of the compressor is worn out, it may hum, but not pump freon with the required force. This condition is called "insufficient discharge capacity."
Diagnostics of the compressor requires measuring the current consumption and discharge pressure. At home, you can only visually assess the integrity of the relay and the absence of obvious signs of burning or melting of the contacts. Replacing a compressor is a labor-intensive process that requires soldering and vacuuming.
Problems with sensors and thermostats
The refrigerator electronics rely on temperature sensor readings. If thermostat or the air sensor in the upper chamber fails and shows incorrect (inflated) values, the controller “thinks” that the cold has already been reached and turns off the compressor ahead of time. As a result, the products at the top begin to deteriorate.
In electronically controlled models, an error in the evaporator defrost sensor is often encountered. If he “lies” that the evaporator temperature is high, the heating element will not turn on, the evaporator will become covered with ice, and the air circulation in the upper chamber will stop. The system may display an error code on the display, but not always.
Checking a mechanical thermostat is possible with a multimeter in dial mode. When the temperature changes, its contacts should open and close. Electronic sensors are checked for changes in resistance when heating or cooling.
Clogged capillary tube and filter drier
The capillary tube is the thinnest channel that creates the necessary throttling (pressure drop) for freon. If there is dirt in the system, oil oxidation products or moisture that has turned into an ice plug, the patency of the tube is impaired. Freon does not enter the evaporator in the required volume, and the upper chamber does not cool.
Often the blockage is accompanied by unusual behavior of the compressor: it can work longer than usual, and the condenser (grid at the back) will only be partially hot - for example, it heats up only to the middle, and then remains cold. This is a sure sign that freon does not go through a full cycle.
Removing the blockage requires purging the system with nitrogen under high pressure and mandatory replacement of the filter-drier. It is impossible to simply “pierce” the plug, since it forms again due to the presence of moisture in the circuit.
Diagnostics and table of symptoms
For correct diagnosis, it is necessary to compare several signs. The behavior of the compressor, the condition of the condenser and the presence of cold in different zones will help narrow down the search. Below is a table that helps classify the problem.
| Symptom | Probable cause | Characteristic symptom |
|---|---|---|
| The compressor is silent, there is no light | No power, burnt out socket | The light inside does not light |
| Buzzes, clicks, does not start | The starting relay is faulty | Clicks every few minutes |
| Works constantly, cold no | Freon leak or blockage | Hot compressor, warm condenser |
| Freezer freezes, top is warm | Fan or sensor faulty | Noise the fan is missing or intermittent |
| Frost only at the entrance to the evaporator | Clogged capillary tube | The condenser is partially heated |
By analyzing the table, you can draw primary conclusions. However, remember that the combination of symptoms can be complex. For example, when working for a long time with a freon leak, the compressor may also burn out due to overheating, since it is not cooled by the returning gas.
⚠️ Attention: If you smell burning or see sparking in the compressor area, immediately disconnect the device from the network. Further operation is a fire hazard.
Procedure for action when a malfunction is detected
If you find that the upper chamber is not cooling, do not panic. The first step is to assess the scale of the disaster. Check that the door is tightly closed and that the seals are not stuck with crumbs. Sometimes the problem is solved by simple defrosting if the No Frost system is blocked by ice.
The following is a testing algorithm that will help the technician quickly diagnose the breakdown over the phone or during a visit. It is important to provide the most accurate information about the behavior of the unit over the past 24 hours.
☑️ Initial check algorithm
After defrosting, turn on the device. If, after 2-3 hours of operation, no cold appears in the upper compartment, and the compressor works without ceasing, then most likely professional repairs are required with the replacement of components or refilling with freon.
Frequently asked questions (FAQ)
Is it possible to operate a refrigerator if the top does not cool, but the bottom does?
Short-term - yes, if you need to store frozen food. However, the compressor will work overload, trying to reach a non-existent temperature, which will lead to rapid wear or burnout of the windings. It is better to turn off the device before the technician arrives.
How long does it take to repair a freon leak?
Finding a leak, eliminating it, replacing the filter and refilling it takes from 1.5 to 3 hours. If the compressor needs to be replaced, the time can increase to 4-5 hours, including the time to evacuate the system.
Why did the refrigerator start working after defrosting, and then stop working again a week later?
This is a classic sign of a micro-leak or blockage. During defrosting, the ice plug in the capillary melts and the system temporarily begins to work. But as soon as the moisture freezes again or the freon completely leaves through a microcrack, the cold disappears.
Does the amount of food in the chamber affect cooling?
Yes, it does. If the top chamber is packed tightly with food, air cannot circulate (especially in No Frost). The cold remains at the back wall, but the center of the chamber is warm. Leave gaps between the food and the back wall for normal circulation.