The situation when the refrigerator does not turn off and continues to hum for days on end causes a reasonable concern for any owner of household appliances. This is not just an annoying noise that disturbs sleep, but also a signal of a serious malfunction in the cooling system. If the unit operates in continuous mode, it consumes a colossal amount of electricity, and the resource of the expensive compressor is rapidly depleted, which can ultimately lead to its complete failure.
Modern models, be it Indesit, Atlant or Bosch, equipped with smart electronics that should automatically stop the motor when the set temperature is reached. However, if you notice that the cooling cycle is not interrupted, and the inside of the chamber becomes too cold or, conversely, the temperature does not drop at all, you must urgently look for the reason. Ignoring the problem can lead to damage to products and expensive repairs.
In this article we will analyze in detail the main reasons why compressor works without stopping, how to carry out initial diagnostics yourself, and in which cases you will need to call a specialist. Understanding the principles of operation of the thermostat and refrigerant will help you quickly identify a malfunction and save your family budget.
Primary diagnostics: external factors and settings
Before you panic and look for tools to disassemble the unit, it is worth eliminating trivial operating errors. Often the reason why the refrigerator does not turn offlies not in the breakdown of parts, but in incorrect operating conditions. First of all, check the temperature. If you accidentally set the maximum cooling or activated the “Super Freeze” function (often indicated by a snowflake or button Super Freeze), the compressor will work continuously, trying to achieve extremely low values.
The second important aspect is the tightness of the chambers. The sealing rubber on the door wears out over time, cracks, or simply becomes covered with ice. A tight fit of the door is a critical factor for stopping the compressor, since any gap allows warm air to pass through, forcing the system to work at full capacity. wear. Check the cleanliness of the seal and make sure that the door closes tightly around the entire perimeter.
It is also worth paying attention to the location of the equipment. If the refrigerator is close to the wall or next to itself (battery, stove), heat exchange is disrupted. A condenser located at the back or sides cannot effectively transfer heat to the environment. As a result condensation temperature increases, the pressure in the system increases, and the motor is forced to work longer in order to cool the chambers to the required values.
- 🌡️ Check whether the temperature regulator is set to the maximum value or in fast freezing mode.
- 🚪 Inspect the sealing rubber for cracks, dirt or deformations that prevent tight closure.
- 🔥 Make sure that the gap between the back of the refrigerator and the wall is at least 5-7 cm for normal air circulation.
Malfunctions of the thermostat and temperature sensors
One of the most common reasons for continuous operation is failure of thermostat (thermostat). This mechanical or electronic component is responsible for opening the compressor power circuit when the temperature in the chamber reaches a predetermined minimum. If the contacts inside the thermostat “stick” in a closed state or the bellows tube breaks, the signal to stop the motor simply does not arrive. In such cases, the refrigerator will freeze until it turns the chamber into a freezer, or until you manually unplug it from the outlet.
In models with a system No Frost and electronic control, the role of a mechanical thermostat is performed by air sensors (thermistors). They are located inside the cameras and transmit data to the control module. If the sensor “lies” and shows that the chamber is still warm, the controller will keep the compressor on. Diagnosis of such faults requires a multimeter to check the resistance of the sensor at different temperatures.
Replacing the thermostat in mechanical refrigerators is a procedure that can be done with your own hands if you have basic skills. It is usually located inside the refrigerator compartment (in a plastic case) or outside, under a teardrop-shaped cover. It is important to choose an analogue with identical parameters, since different models (for example Stinol, Liebherr) may have different capillary tube lengths and operating temperature ranges.
How to check a mechanical thermostat?
To check a mechanical thermostat, you can remove it and place the sensitive tube in a container with ice. If during cooling you hear a click of the contacts opening (checked by checking the continuity of the multimeter), then the thermostat is working. The absence of a click indicates the need for replacement.
⚠️ Attention: Before replacing the thermostat, be sure to disconnect the refrigerator from the power supply. Do not try to adjust or repair the internal mechanical parts of the thermostat - they cannot be restored, only replaced.
Problems with refrigerant: freon leak
The situation when the refrigerator does not turn off, but it freezes slightly or does not freeze at all, often indicates a refrigerant leak (freon). In a working system, the refrigerant circulates in a closed circuit, changing its state of aggregation and taking heat from the chambers. If a microcrack appears in the evaporator or condenser tubes, the gas gradually evaporates. The pressure in the system drops, and the compressor, trying to compensate for the lack of cooling capacity, operates in continuous mode.
It is not always possible to visually diagnose a leak, since freon is colorless and odorless. However, an experienced technician may notice the absence of characteristic heating of the condenser grille at the back of the refrigerator or, conversely, local overheating of the compressor. In some cases, oily spots are visible on the tubes at the leak site, as the oil circulates along with the gas. Finding a leak on your own without a leak detector and a pressure gauge station is almost impossible.
Repair in this case does not simply involve “refueling”. It is necessary to find the place of damage, solder it and only after evacuating the system, fill in a new volume of freon. Using the wrong type of refrigerant (for example R600a instead of R134a) can lead to an explosive situation or failure of the compressor.
Malfunctions of the compressor and start relay
The compressor is the “heart” of the refrigerator, and its incorrect operation directly affects the cycle of switching on and off. If motor-compressor lost its performance due to wear of the piston group or valves, it will not be able to create the necessary pressure for effective circulation of freon. As a result, the temperature in the chambers does not drop to the set point, and the thermostat does not give the command to stop. The motor wears out, gets very hot and hums.
Another common problem is a malfunction of the start-protection relay. This small element is responsible for starting the engine and protecting against overloads. If the relay is “stuck” or its contacts are burnt, it may not open the power circuit, leaving the compressor on constantly. In some cases, the relay, on the contrary, clicks and turns off the motor, but due to a breakdown cannot start it again, although in the context of our topic we are interested in the continuous operation mode.
Diagnostics of the compressor requires measuring the current consumption. If the current is less than rated, it indicates a loss of performance (turn-to-turn short or wear). If the current is higher, there may be a mechanical overload or electrical problems. Replacing a compressor is a complex process that requires welding copper tubes and professional refueling of the system.
| Symptom | Probable cause | Nature of work |
|---|---|---|
| Hums constantly, cools weakly | Freon leak | Continuous, cold condenser |
| Buzzes constantly, gets very cold | Thermostat is faulty | Continuous, there is ice in the chamber |
| Buzzes, gets hot, does not turn off | Wear compressor | Continuous, high current |
| Humming, clicking, does not turn off | Stuck relay | Constant operation or frequent cycles |
Failures in the system No Frost and defrosting
In refrigerators with a system No Frost the reason for continuous operation of the compressor is often problems with evaporator defrosting. If the defrost heater, thermal fuse, or defrost sensor fails, a “coat” of ice builds up on the evaporator in the freezer (which is hidden behind a plastic panel). This ice blocks the cold air circulation channels.
The fan, which should drive cold air into the refrigerator compartment, either stops due to icing, or drives warm air because the evaporator is blocked by ice. The temperature sensor in the refrigerator compartment detects the increase in temperature and instructs the control module to turn on the compressor. The motor runs non-stop, trying to cool the chamber, but due to the ice plug this is impossible.
For diagnostics, you need to defrost the refrigerator completely (within 24 hours with the doors open). If after defrosting the unit begins to operate in normal cyclic mode, then the problem lies precisely in the defrosting system. You will need to check the heater circuit and sensors.
☑️ Diagnostics of the No Frost system
The influence of external temperature and seasonality
Do not forget that the operation of the refrigerator directly depends on the ambient temperature. If you install the unit on an unheated balcony, garage or kitchen, where the temperature rises above +30°C in summer, the compressor can operate almost without interruption. This is explained by the laws of physics: the higher the temperature in the room, the worse the condenser gives off heat, and the longer the motor must work to cool the chambers.
Most household refrigerators have a climate class SN (subnormal) or N (normal), which means operating at ambient temperatures from +10°C to +32°C (sometimes up to +38°C). Exceeding these limits leads to the fact that the refrigerator simply cannot turn off, since it does not reach the thermostat cut-off point. This is not a breakdown, but operation in unsuitable conditions.
In winter, the situation may be the opposite, but also problematic. If the refrigerator is in a cold room (below +10°C), the oil in the compressor thickens and the freon circulates less well. In some models, this can lead to incorrect operation of the thermostat, which “does not see” sufficient heating and does not turn off the motor, or, conversely, does not turn it on. However, more often in winter there is a “simple” refrigeration chamber with the freezer running.
⚠️ Attention: Operating the refrigerator at temperatures below +5°C or above +35°C can lead to rapid breakdown of the compressor and void the warranty. Make sure that the indoor conditions correspond to the climate class indicated on the sticker inside the chamber.
When professional repairs are needed
If simple methods - defrosting, checking settings and cleaning the condenser - did not help, and the refrigerator does not turn offmost likely, professional intervention will be required. Complex cases, such as finding micro-leaks of freon, replacing a compressor, or repairing an electronic control module, require specialized equipment and knowledge. Attempts at self-repair in these cases can lead to permanent breakdown of the unit.
It is especially dangerous to open the refrigeration circuit yourself. Residual pressure, presence of oil and specific properties of refrigerants require caution. In addition, modern refrigerators with inverter compressors have complex electronics, the diagnosis of which is impossible without service software and programmers.
Calling a technician in a timely manner will help save money. Repair at an early stage (for example, replacing a thermostat or eliminating a small leak) will cost much less than replacing a compressor or the entire refrigerator that has burned out due to overheating.
Frequently asked questions (FAQ)
How long should the refrigerator work before turning off?
In normal mode, the refrigerator operates cyclically: it works (cools) for about 10-20 minutes and rests for 20-40 minutes. The ratio depends on the camera load, room temperature and settings. If the motor runs for more than 40-50 minutes in a row without stopping, this is a cause for concern.
Can the refrigerator not turn off due to the heat outside?
Yes, high ambient temperatures (above +30°C) cause the compressor to work longer and more often. If the room is very hot, interruptions may be kept to a minimum, but a complete stop must still occur. If it does not turn off at all, perhaps it cannot cope with the load or there is a malfunction.
Is it dangerous if the refrigerator hums and does not turn off?
Yes, it is dangerous. Long-term operation without stopping leads to overheating of the compressor windings, which can cause them to burn out. This also leads to excessive consumption of electricity and possible spoilage of food due to temperature violations.
Why does the new refrigerator not turn off?
When turned on for the first time, a new refrigerator can work for up to 24 hours without turning off. This is normal, since it needs to cool a large volume of the interior and walls from room temperature to operating temperature. If after a day of operation it does not turn off, check the settings and how tightly the doors are closed.