The situation when the refrigerator hums without interruption immediately after defrosting is completed causes natural concern for any owner. It would seem that you have completed all the necessary procedures for caring for the equipment, let the ice melt, wiped the chambers and turned on the device, but instead of the usual “work-rest” cycle, the unit switched to continuous cooling mode. This behavior of the system often indicates that the internal automation does not see the achievement of the set temperature or the sensors transmit incorrect readings to the controller.
In most cases, the reason lies not in the breakdown of itself compressor, but in heat transfer disturbances or malfunctions in the thermoregulatory system. If you are faced with the fact that inverter or a conventional motor is wearing out, this can lead to serious consequences, including overheating of the windings and failure of expensive components. It is important to quickly identify the source of the problem in order to prevent damage to products and further complicate repairs.
There are a number of factors that can provoke such an anomaly, ranging from simple inattention during assembly to refrigerant leakage. In this article we will analyze in detail the mechanics of the process, typical user errors during operation after defrosting, and technical malfunctions that require specialist intervention. Understanding the physical processes inside the chamber will help you quickly make the right decision.
Violation of tightness and assembly errors
The most common reason why a refrigerator cannot reach the temperature and turn off is trivial - a violation of the tightness of the circuit. During defrosting, you've probably removed shelves, drawers, and maybe even removed doors for easy cleaning. If after assembly sealing rubber it does not fit tightly, warm air from the room constantly flows inside, causing the temperature sensors to record the heating.
Often users forget to completely close the door or leave a gap due to a foreign object getting there. Even a microscopic gap of a few millimeters creates a constant flow of heat, which the cooling system simply cannot cope with. As a result, the compressor works 24/7, trying to compensate for heat loss.
⚠️ Attention: If the sealing rubber was damaged during cleaning with sharp objects or was greatly stretched, replacement may be the only way out. Check the integrity of the cuff along the entire perimeter.
It is also worth checking whether the door shelves are installed correctly. If they are misaligned or askew, they can physically prevent the sash from closing tightly. Make sure that the products that you returned to their place after defrosting do not support the door from the inside.
☑️ Checking the tightness
Failures in the operation of the thermostat and sensors
The thermostat (thermostat) is the “brain” that commands the compressor to turn on or off. In older mechanically controlled models, this device is a capillary tube that responds to changes in temperature. If after defrosting you turn on the refrigerator, but it does not turn off, it may be thermostat stuck in the “On” position or its sensitive element has moved.
In modern models with a system No Frost and electronic control, air sensors are responsible for the temperature. During defrosting, moisture could get onto the sensor contacts or into the wiring connectors, causing a short circuit or distortion of the readings. In this case, the controller receives a false signal that the chamber is “warm” and does not give a command to stop the engine.
Sometimes the problem lies in incorrect temperature settings. The user may accidentally set the “Super Freeze” mode or the minimum temperature at which the refrigerator should not really turn off for a long time. Check the settings on the display or the position of the control knob.
Symptoms of a sensor malfunction are often accompanied by an incorrect temperature display on the screen or a complete lack of response to changing settings. If you suspect electronics, self-repair without special knowledge and equipment can be dangerous.
How to check a mechanical-type thermostat?
Unplug the refrigerator, remove the regulator knob and get to the thermostat housing. Carefully remove the capillary tube from the evaporator. If the refrigerator starts working when plugged in and the contacts are closed, but does not turn off when the thermostat body heats up in your hands, the device is faulty and requires replacement. Be careful not to damage the tube!
Problems with the defrost system (No Frost)
If your refrigerator is equipped with an automatic defrost system No Frostthen continuous operation of the compressor may be the result of a malfunction in the defrost cycle. During the process of manual defrosting (if you carried it out for such models) or simply over time, the timer or defrosting sensor could fail. Defrosting heating element, timer or defrost sensor.
When the defrosting system does not work correctly, ice builds up on the evaporator, which is hidden behind the back wall of the freezer fur coat This ice blocks the circulation of cold air. The temperature sensor in the main chamber does not detect cooling, since cold air does not reach it, and commands the compressor to continue working.
Visually it may look like this: the refrigerator is humming, but it is warm inside, or it is cold in the freezer, but not in the refrigerator compartment. An attempt to cool the chamber under such conditions leads to an overload of the system.
| System component | Function | Malfunction sign |
|---|---|---|
| Defrost heating element | Heating of the evaporator for ice melting | Ice build-up on the evaporator |
| Defrost sensor | Evaporator temperature control | No start of the heating element or its operation without stopping |
| Timer/Controller | Switching "Cooling/Defrosting" modes | The refrigerator does not go into defrost mode |
| Fan | Air circulation | Noise, lack of airflow, ice on the blades |
Refrigerant leak and capillary system clogged
A more serious technical problem is the leakage of the freon circuit. If a microcrack has formed in the system, the quantity refrigerant reduces. The compressor tries to compensate for the lack of freon by working in enhanced mode, but cannot reach the set temperature.
Often a leak occurs during the defrosting period or immediately after it, if the user has shown excessive diligence, picking out the ice with a knife or sharp objects. Damage to the evaporator is a critical failure that requires professional repair with replacement of the unit and refilling with gas.
Another option is a clogged capillary tube. Oil and freon circulate in the system, and over time, plugs from waxed oil or decomposition products may form. This disrupts the circulation of the refrigerant, the pressure in the system drops, and the refrigerator does not cool, working without stopping.
⚠️ Attention: Never try to solder the pipes yourself or add freon “by eye”. This requires evacuation of the system and precise dosing of the refrigerant, otherwise the compressor will burn out in a matter of days.
A sign of a leak is often a quiet hiss (if the hole is large) or the complete absence of the characteristic sound of gas flowing in the condenser tubes when the engine is running. Also, the rear grill of the refrigerator may remain cold or only partially heat up.
The influence of ambient temperature and load
Do not discount external factors. If you defrosted the refrigerator in the summer in a hot room, or it is located next to the stove and radiators, the system requires significantly more time and energy to cool. After defrosting, the chamber walls and internal elements (shelves, drawers) are at ambient temperature and need to be cooled.
If you have loaded a large amount of warm food into the refrigerator that has just been turned on, the compressor will work continuously until the temperature stabilizes. This is a normal physical reaction, and not a breakdown.
It is also important to take into account the climate class of the equipment. If refrigerator, designed for a temperate climate (SN, N), is in an unheated room at a temperature below +10°C or, conversely, in a very hot kitchen (+35°C and above), the thermostat may behave incorrectly or the system will not cope with the load.
Faults of the compressor and start relay
The most expensive reason is wear of the compressor itself. Over time, the engine loses its power (compression). It may hum, create vibration, but not build up enough pressure in the system. As a result, freon circulates, but does not cool.
It also often fails starting relay. This small element is responsible for starting the engine. If the relay contacts are burnt or stuck, the compressor may not start, may hum and click, or may run continuously without receiving a signal to stop. In some cases, the relay “sticks” in the on position, constantly supplying power to the windings.
It is difficult to determine the problem with the compressor yourself, but you can pay attention to its temperature. If the engine has been running for several hours and remains cold (while humming), this is a bad sign. If it is hot to such an extent that it is impossible to touch it, there may be an interturn short circuit or a wedge in the mechanical part.
Frequently asked questions (FAQ)
How long should the refrigerator take to reach temperature after defrosting?
Usually, the initial cooling of empty chambers takes from 2 to 6 hours, depending on the model, volume and ambient temperature. Complete stabilization of the food regime may take up to 24 hours. If the temperature has not reached normal within a day, look for a malfunction.
Is it possible to leave the refrigerator on overnight after defrosting?
Yes, this is even necessary. After defrosting, it is recommended to leave the appliance turned on for at least 8-10 hours without loading food, so that the system enters the operating cycle and makes sure it is able to maintain the temperature.
Why does the refrigerator click but does not turn off?
Clicks can be made by the thermostat (normal operation) or a thermal protection relay (attempt to start). If the clicks are frequent and the refrigerator does not turn off, the start relay may be stuck or the thermostat is faulty.
Is it dangerous if the compressor runs without stopping?
Yes, it is dangerous. The compressor life is designed for cyclic operation. Under constant load, the oil loses its properties, the windings overheat, which inevitably leads to engine combustion. It is necessary to eliminate the cause.