The situation when the compressor the refrigerator hums for days on end, is familiar to many owners of household appliances. This is not just an annoying noise that disturbs sleep, but also a serious signal that there is a failure in the cooling system. If the unit stops clicking and goes to rest, it means that it is trying, but cannot reach the set temperature, or the sensors have stopped transmitting correct signals to the controller.
Ignoring this problem can lead to overheating of the engine, melting of the wiring and, ultimately, to expensive repairs or complete replacement of the equipment. In some cases, the reason lies in a banal violation of operating rules, and you can fix it yourself in a couple of minutes without calling a technician.
However, there are also complex technical faults that require the intervention of specialists with professional equipment. Understanding the principles of operation refrigeration circuit will help you quickly determine the nature of the breakdown and make the right decision on further actions.
Primary diagnosis and simple causes
Before you panic and look for the service center number, you need to exclude external factors that often remain without attention. Very often the refrigerator does not turn off due to the fact that the user accidentally set the mode Super Freeze or Max Cool. In this mode, the equipment operates in enhanced mode until you manually turn off the function, ignoring standard temperature thresholds.
It is also worth checking the tightness of the door. If the sealing rubber is worn out, dirty or simply deformed, warm air from the room constantly enters the chamber. The compressor is forced to work continuously, trying to cool this constant flow of heat, which is especially noticeable in the summer.
It is important to pay attention to the location of the unit. If the refrigerator is placed close to the wall or in a niche without the necessary clearance for ventilation, heat exchange is disrupted. The radiator on the rear wall heats up, but cannot transfer heat to the environment, which is why the sensors record high temperatures and do not give a command to stop the motor.
Modern models with the No Frost system they are especially sensitive to overheating of the condenser. Make sure that there is at least 5-10 centimeters of free space around the case on all sides, including the top.
A common cause is also loading warm or hot products into the chamber. The thermostat has detected a sharp rise in temperature and requires time to return the environment to normal. In this case, continuous operation for several hours is normal operation, and not a breakdown.
Faults of the thermostat and sensors
One of the most common technical reasons for endless operation is the failure of the thermostat. This element is responsible for monitoring the temperature inside the chambers and sending a signal to turn the compressor on or off. If the contacts inside the thermostat are “stuck” in the “on” position, the motor will work until it burns out or is de-energized.
In electronically controlled refrigerators, the function of a mechanical thermostat is performed temperature sensors (thermistors). They change their resistance depending on heating or cooling. If the sensor “lies” and shows the controller that the chamber is +10°C instead of the real -5°C, the system will drive the compressor endlessly.
How to check the thermostat with a multimeter?
To diagnose a mechanical thermostat, it must be removed and “ringed” with a tester. In a cold state, the contacts should be closed (resistance close to 0), and when heated, they should open. If the circuit does not break when heated, the part is faulty.
Replacing the thermostat in most models is a simple procedure. It is usually located inside the refrigerator compartment in a plastic case or outside the case in older models. It is enough to remember the wire connections and install a new part with the same marking.
However, in models with electronics, replacing the sensor may require entering the service menu for calibration or error reset. Incorrectly selected sensor resistance can lead to incorrect operation of the entire unit.
Refrigerant leak and problems with the compressor
If the refrigerator hums, but does not produce cold (or produces very little), and does not turn off, there is a high probability of a freon leak. A hole formed in the system through which it evaporated refrigerant. The pressure in the circuit has dropped, and the compressor, trying to compensate for the lack of cold, is wearing out.
It is difficult to determine the leak visually, since freon is colorless and odorless. However, indirect signs may be swelling of the refrigerator wall (at the sealing point of the circuit) or, conversely, the absence of characteristic heating of the side walls when the motor is running.
Another serious problem is the loss of performance of the compressor itself. Over time, the valves inside the motor wear out, and it ceases to create the necessary pressure for gas circulation. The motor runs and hums, but does not pump freon with the required efficiency. In this case, the compressor needs to be replaced, since this unit is usually not subject to repair.
An attempt to fill the refrigerator with freon yourself without finding and eliminating the leak will only lead to a short-term effect and repeated breakdown in a few days or weeks.
Clogged capillary tube and moisture in the system
Circulation The refrigerant flows through a thin capillary tube. If a blockage forms in the circulation system (due to oxidation products introduced during poor-quality repairs, or frozen moisture), freon cannot pass freely through the circuit.
Signs of a blockage are often the strange behavior of the unit: it can work for a long time, then suddenly stop working, and after a while it starts again. Or the condenser (grid at the back) will only be half hot, and the other part will remain cold. This indicates that the gas does not reach the end of the circuit.
Moisture in the system is the “mortal enemy” of the refrigerator. It gets there due to poor-quality vacuumization during repairs. Freezing in the capillary, water creates an ice plug that blocks the freon flow. After disconnecting, the ice melts, the plug disappears, and the cycle repeats.
To eliminate this problem you need:
- ⚙️ Complete desoldering and purging of the circuit with nitrogen.
- 💨 Replacing the filter-drier with a new one.
- 🔌 High-quality vacuumization of the system before refueling.
Table of symptoms and probable causes
To quickly navigate the problem, use the following table. It will help narrow down the search for a malfunction.
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| Motor hot, no cold | Freon leak or blockage | High (needs a technician) |
| The engine runs constantly, there is cold | Thermostat/sensor is faulty | Medium (you can do it yourself) |
| Intermittent humming, clicks | Problems with the start relay | Low (part replacement) |
| Frost only at the entrance to the chamber | Lack of freon | High (search leaks) |
Problems with the defrost system (for No Frost)
In refrigerator systems No Frost continuous operation compressor may be caused by a malfunction of the evaporator defrost system. If the defrost heating element, timer or defrost sensor fails, a “coat” of ice grows on the evaporator.
Ice blocks air circulation. The refrigerator hums, trying to cool the chamber, but the cold air simply cannot pass through the icy shell to the food. Visually, there may be warmth in the chamber, and there may be a block of ice behind the back panel.
For diagnostics, it is often enough to remove the back plastic panel in the freezer. If the evaporator is covered with snow or ice, the problem must be found in the defrost circuit. Check the integrity of the heating element and the resistance of the sensor.
⚠️ Attention: Before removing the panels and diagnosing the electrical part, be sure to disconnect the refrigerator from the power supply! Working with 220V voltage is life-threatening.
When you need to call a technician
There are a number of situations when self-repair is not only impractical, but also dangerous. If you find oily spots under the refrigerator or on the condenser tubes, this is a sign that oil has leaked along with the freon. The tightness is seriously compromised.
Also, you should not undertake repairs if welding of pipes is required. Using a burner at home without proper ventilation and skills can lead to a fire or damage to the plastic elements of the refrigerator body.
If the situation has not changed after replacing the thermostat, the problem may be deeper - in the control module. Electronics diagnostics require special knowledge and circuitry. Incorrect intervention can completely “kill” the control board.
☑️ Checklist before calling a technician
⚠️ Attention: Modern refrigerants (for example, R600a - isobutane) are explosive at a certain concentration in air. Puncture of the system without professional equipment is prohibited.
Prevention and proper care
To extend the life of the compressor and avoid situations with continuous operation, it is important to follow simple operating rules. Regularly, at least once a year, defrost the refrigerator (even the No Frost system) for prevention and wash the drainage hole.
Keep the back of the condenser clean. Dust and pet hair that stick to the grille act as a heat insulator, causing the motor to work harder. Vacuuming the back wall is a good habit.
Do not overload the camera with products. For normal air circulation, there must be space between products. If you fill the freezer to capacity, the cold will not be able to be distributed evenly, and the sensors will “drive” the motor.
The correct temperature setting also plays a role. Do not set the regulator to maximum unless necessary. To store most products, +4...+5°C in the refrigerator compartment and -18°C in the freezer are enough.
Why can’t you put hot food in the refrigerator?
This not only forces the motor to work to the limit, but also increases the temperature inside the chamber, which can lead to spoilage of other products and the growth of bacteria.
Often asked questions (FAQ)
How long can the refrigerator work without stopping after being turned on?
In normal mode, after the first turn on or after defrosting, the refrigerator can gain temperature from 2 to 12 hours, depending on the volume and ambient temperature. If it does not turn off for more than 24 hours, this is a malfunction.
Can the refrigerator not turn off due to the heat in the room?
Yes, if the room temperature is above +30...+32°C, heat exchange is disrupted. The compressor can run almost continuously, trying to maintain the cold. This is an extreme mode that reduces the life of the equipment.
Is it dangerous to leave a refrigerator running overnight?
If the reason for continuous operation is a malfunction (leakage, short circuit), leaving it unattended is dangerous. Possible overheating of the wiring and fire. It is better to turn off the power to the appliance before the technician arrives.
Why doesn’t a new refrigerator turn off for a long time?
When first started, an empty refrigerator takes a long time (up to a day) to cool the body and shelves. This is fine. You can speed up the process if you immediately add food, but without overloading the chamber.
What to do if the refrigerator is humming, but not freezing?
Most likely, there is a freon leak or a blockage. You need to turn off the device, defrost it and call a specialist to diagnose the circuit. Operating in this mode will kill the compressor.