The situation when refrigerator makes the usual hum, but inside the temperature rises to room temperature, causes panic in anyone housewives. Food begins to spoil, and the ice in the freezer melts. This is a classic symptom of a refrigerant circulation problem or a malfunction of the heat removal system.
Before calling a technician or trying to disassemble the unit, it is necessary to conduct an initial visual diagnosis. Often the problem lies in small things that can be easily fixed on your own without resorting to complex repairs. However, ignoring the sounds of a working compressor compressor in the absence of cold can lead to its complete combustion.
In this article we will analyze in detail the mechanics of the cooling process, identify the main causes of the malfunction and determine in which cases repairs are possible with your own hands, and when professional intervention is required. Understanding the principle of operation will help you save time and money.
⚠️ Attention: If you hear that the motor is humming more than usual, and then there is a click and it goes silent (or vice versa, it hums continuously without turning off for hours), immediately unplug the device from the network. Further operation in this mode is guaranteed to disable the compressor.
Operation principle: why is it humming, but not cooling?
To understand the essence of the problem, you need to briefly remember how the cooling cycle works. Compressor compresses gaseous freon, turning it into a hot liquid under high pressure. Then the refrigerant passes through the condenser (grid at the back), where it cools, and enters the evaporator inside the chambers, where it expands sharply and boils, taking away heat.
If the motor is running, then the electrical circuit is intact, and the starting relay is trying to start the unit. However, the absence of cold indicates that the freon circulation is broken or the heat is not removed properly. The refrigerant may simply stand still without going through a full cycle, or its pressure is not enough for effective boiling.
In some cases, the compressor runs “idle”. This occurs when the valves inside it have worn out and it cannot generate the necessary pressure to move gas through the system. Visually this looks like normal operation, but technically the unit no longer performs its function.
Refrigerant leak: the most common diagnosis
The most common reason why refrigerator stopped freezing when the engine is running is a banal freon leak. The refrigerant circulates in a closed circuit, but over time, the metal of the evaporator tubes can corrode, especially if low-quality material was used or mechanical damage occurred during defrosting.
Leakage symptoms often appear gradually. First temperature it begins to “float”, then the freezer stops freezing, and in the main compartment the food is simply warm. At the same time, the compressor works without interruption, trying to compensate for the lack of pressure, which leads to its severe overheating.
Sometimes a leak occurs in the foamed part of the housing, which makes repairs difficult and expensive. In such cases, craftsmen may suggest installing an external evaporator (“crying” on the back wall inside the chamber), which is a temporary but working solution.
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| Motor is hot, cold no | Freon leakage | High (vacuum depressor required) |
| Humming with clicks | Faulty start relay | Low (part replacement) |
| Ice only at the entrance to the evaporator | Clogged capillary tube | Medium (system purge) |
| The refrigerator turns off quickly | Thermostat failure | Low |
Problems with the compressor and starting relay
If motor it hums, but does not start, or starts and immediately stalls with a characteristic click, the problem lies in the starting-protective relay or the motor windings. A relay is a small plastic block that fits onto the compressor contacts. Its task is to provide an impulse to start and turn off the starting winding.
Over time, the relay contacts burn out, or the bimetallic plate loses its properties. As a result, the compressor cannot reach the required speed. This is easy to check: if you remove the relay and shake it, there should be no rattling sound inside (unless this is a design feature of a particular model, which is rare).
A more serious problem is an interturn short circuit in the windings itself. compressor. In this case, the engine may hum, heat up, but not develop enough power to compress the gas. Diagnostics requires measuring the resistance of the windings with a tester. If the resistance tends to zero or infinity, the unit must be replaced.
⚠️ Attention: Replacing a compressor is a complex procedure that requires soldering copper tubes, evacuating the system and accurately filling with freon. It is almost impossible to do this efficiently at home without a pressure gauge station.
How to check the starting relay yourself?
Remove the relay from the compressor contacts. Shake it. If you hear a ball knocking inside, the mechanism is most likely destroyed. Also inspect the contacts: the presence of carbon deposits or melted plastic indicates the need for replacement.
Clogged capillary tube and filter drier
There is a bottleneck in the freon circulation system - the capillary tube. This is where the sharp drop in pressure occurs. If moisture remains in the system or debris gets in during production, an ice plug or blockage forms in this place. Freon stops circulating and cooling stops.
Often the blockage is accompanied by unusual behavior of the compressor: it works quieter than usual or, conversely, with increased noise, and the condenser (grid at the back) heats up unevenly - only part is hot, the rest is cold. This is a sure sign that the gas does not pass beyond a certain area.
To eliminate this malfunction, it is necessary to purge the system with high pressure nitrogen and replace the filter drier. The filter retains moisture and oil breakdown products, and if it is clogged, its capacity drops to zero.
Faults in the No Frost system
In refrigerators with the system No Frost another layer of possible problems is added. Here the cold is forced by a fan through the air ducts. If the motor is running, but the cold does not enter the chamber, the evaporator behind the plastic panel may have frozen.
The reason may be a failure of the Defrost heating elementtimer or defrost sensor. Ice builds up on the evaporator, blocks the channels, and the fan drives warm air around the chamber. This can be seen visually if you remove the back plastic panel in the freezer (after defrosting the unit).
Also, the fan itself often breaks. If its impeller is frozen or the motor is burned out, air circulation is impossible. In modern models, this may be indicated by an error on the display or a sound signal.
☑️ Diagnostics of the No Frost system
The influence of external factors and operating rules
Sometimes the reason lies not in the breakdown, but in the operating conditions. If refrigerator stands close to the wall or in a niche without gaps, heat is not removed from the condenser. The motor overheats, the thermal protection is triggered, and the cycle is interrupted without having time to cool the chambers.
Densely stuffing food also disrupts circulation. The air should flow freely around the food. If you fill the freezer to capacity, the cold simply will not be able to spread throughout the entire volume, although formally the unit will work properly.
It is important to take into account the temperature in the room. If the refrigerator is in an unheated garage or on a balcony at a temperature below +10°C, the oil in the compressor thickens and it cannot start or does not work efficiently. Most models are not designed to operate in low ambient temperatures.
⚠️ Note: Specifications and installation requirements may vary by model and year of manufacture. Always check the manufacturer's instructions (section "Climate class") before installing equipment in non-standard conditions.
When is it necessary to call a technician?
You can replace the light bulb yourself, wash the drainage hole, or even change the thermostat/relay if you have electrical skills. However, any manipulations related to refrigerant and a sealed circuit require special equipment and a license.
If you determine that the problem is a freon leak, a clogged capillary or a breakdown of the compressor itself, calling a specialist is inevitable. The technician will arrive with pressure gauges, a vacuum pump and a supply of freon, which will allow the repair to be carried out efficiently and provide a guarantee.
An attempt to “add” freon without eliminating the leak or replacing the compressor without evacuation of the system will only lead to a temporary effect and the final breakdown of the expensive unit in a short time.
Is it worth repairing the old one? refrigerator?
If the refrigerator is more than 10-12 years old and requires a compressor replacement or foam evaporator repair, it is often cheaper and more reliable to buy new equipment. Repairs can amount to up to 70% of the cost of a new unit.
Frequently asked questions (FAQ)
Why does the refrigerator hum, but does not freeze after defrosting?
If after complete defrosting (24 hours) the situation has not changed, there is probably a freon leak or a blockage has formed. The thermostat could also have failed, which “does not see” that the chamber is warm and does not give the command for full cooling.
Is it possible to add freon yourself?
Absolutely not. For this you need a pressure gauge station, scales and soldering skills. The wrong amount of freon (either underfilling or overfilling) will instantly kill the compressor.
The refrigerator works without stopping, but does not freeze well. What to do?
This is a classic sign of a refrigerant leak or a clogged system. The compressor tries to compensate for the lack of cold by operating in emergency mode. You urgently need to turn off the device and call a technician.
How to understand that the compressor has burned out?
If you hear a loud click when you turn it on, the motor hums for 1-3 seconds and clicks again, turning off - most likely the problem is in the start relay or compressor wedge. If it hums smoothly, but is very hot and does not cool, a breakdown of the valves is possible.