The situation when the refrigerator hums continuously, and the food inside begins to freeze or, conversely, thaw, causes panic in any owner. Constant operation of the motor-compressor is not only a risk of damage to the food supply, but also a direct threat of failure of the unit itself. Engine, designed for cyclic operation, simply overheats from continuous load.
In normal condition refrigerator compartment must cool to the set temperature, after which the automation gives a command to stop. If this does not happen, then one of the key heat transfer or control processes is disrupted. In this article, we will analyze in detail the mechanical and electrical causes of the malfunction.
It is important to understand that ignoring the hum can lead to expensive repairs or the need to purchase new equipment. A critical sign of a breakdown is the operation of the compressor for more than 24 hours without a single stop cycle. Let's find out what exactly makes your refrigerator work in emergency mode.
Malfunctions of the thermostat and temperature sensors
The most common reason for endless operation is the failure of the thermostat. This small device is responsible for reading the temperature inside the chamber and sending a signal to turn the motor on or off. If the contacts inside thermostat are stuck in the closed position, the compressor will work until it burns out.
In modern models with a system No Frost and electronic control, the role of a mechanical regulator is performed by air sensors. They may give incorrect readings due to oxidation of contacts or moisture ingress. The control system “thinks” that it is warm in the chamber and causes the motor to wear out.
⚠️ Attention: When diagnosing the thermostat in refrigerators with electronics, do not close the contacts arbitrarily, this can lead to burning of the control board.
To check a mechanical thermostat, they often use the method of temporarily excluding it from the circuit. However, this requires caution. If the motor stops after disconnecting the sensor, the problem lies with it.
How to check a thermostat with a multimeter
For diagnostics, remove the thermostat and “ring” its contacts with a tester. In the normal state (at room temperature) the circuit should be closed. If you put the sensor in the freezer for 15-20 minutes, the circuit should open. If the opening does not occur, the device is faulty.
Replacing the thermostat is not the most complicated procedure, but it requires precision. In some models, access to it is blocked by decorative panels, which can easily be damaged if opened carelessly.
Refrigerant leakage and problems with compression
The second most common reason is a banal shortage freon in the system. The refrigerant circulates through the tubes, taking heat from the chambers. If a microcrack has formed in the circuit (often in the foamed part of the housing or in the evaporator), the gas gradually evaporates.
When freon becomes low, there is not enough cold to achieve the set temperature. Electronics or a thermostat detects “heat” and does not allow the compressor to rest. The motor runs around the clock, trying to compensate for the leak, but to no avail.
- 🔍 Signs of a leak: slight cold in the freezer, hot side walls, no freezing of the rear wall.
- 🔧 Consequences: working for wear leads to overheating of the motor windings.
- 🛑 Danger: some types of freon in combination with oil can form aggressive compounds when in contact with air.
Also, the problem may lie in the compressor itself. If the piston rings or valves are worn out, the unit loses compression. It hums and vibrates, but does not create enough pressure for normal gas circulation. In this case, even a full charge of freon will not help.
☑️ Diagnosis of freon leakage
Problems with tightness and thermal insulation
Often the owners themselves create the conditions for continuous operation of the equipment, without knowing it. Violation of tightness of the refrigerator compartment leads to a constant influx of warm air. The motor is forced to work without stopping to cool the incoming heat.
First of all, pay attention to the door seals. Over time, they dry out, crack or become deformed. If the door does not fit tightly, moisture penetrates inside and freezes on the evaporator, further impairing heat transfer.
You can check the tightness with a simple sheet of paper. Clamp the sheet between the door and the body around the perimeter. If the paper is removed without force, the seal requires replacement or adjustment.
Another factor is frequent opening of doors or placing the refrigerator next to heat sources (battery, stove). In such conditions, heat inflows are so great that even a serviceable unit may not be able to cope with the load, especially in summer.
Faults in the starting relay and electronics
The starting relay is a device that starts the engine and protects it from overloads. If the relay contacts are burnt or the mechanism is stuck, the compressor may not receive a signal to stop or, conversely, constantly tries to start.
In models with an electronic control module (board), the problem may be software or a failure of the triac that controls the motor. If the “brains” of the refrigerator freeze or a key element of the circuit burns out, the shutdown command simply does not arrive.
| Type of fault | Symptoms | Probability of repair |
|---|---|---|
| Stuck relay | Humming, clicking, motor does not stall | High (relay replacement) |
| Board failure | Chaotic operation, errors on the display | Medium (flashing/replacement) |
| Open sensor circuit | Constant operation, no response to temperature | High (sensor replacement) |
| Compressor wear | Loud noise, overheating, poor cooling | Low (unit replacement) |
Diagnostics of electronics requires special knowledge and equipment. You can only visually inspect the board yourself for blackening or swollen capacitors.
The influence of the fast freezing mode
Sometimes the reason lies not in a breakdown, but in a forgotten function. The Super Freeze mode forcibly turns off the thermostat and forces the compressor to work continuously to quickly reduce the temperature.
Usually this mode is activated by a button on the control panel or by turning the knob to the extreme position. In older models, it can turn off automatically after a certain time, in new ones it requires manual shutdown.
Check the control panel. If the snowflake light or "Super" sign is on, simply turn this feature off. The motor should stop within 15-30 minutes after the temperature normalizes.
⚠️ Attention: Long-term operation in super-freezing mode (more than 2-3 days) unnecessarily can lead to excessive energy consumption and a reduction in the compressor life.
Operating errors and external factors
Do not Banal mistakes should also be discounted. Loading a large amount of warm food into the chamber creates a huge load. The refrigerator will work without interruption until it cools the entire volume.
The location of the equipment also affects. If the refrigerator is placed close to the wall, the air circulation around the condenser (the black grille at the back) is disrupted. The unit overheats and gives off heat less well, which makes the compressor work longer.
Drafts or direct sunlight can also disorient the temperature sensors, causing the system to work harder. Make sure that the equipment is installed in accordance with the manufacturer's instructions.
When you need to call a technician
If you have checked all external factors, defrosted the unit and made sure the seals are intact, but the compressor continues to hum for days - you can’t do it without a specialist. Especially when it comes to finding a leak or replacing a compressor.
Independent repair of the freon circulation system is prohibited without a license and special equipment (vacuum pump, filling station). Unprofessional intervention can finally finish off the equipment.
The technician will diagnose the pressure in the system, check the current consumption of the engine and, if necessary, replace faulty components. This guarantees safety and preservation of the warranty (if it is still valid).
Can the refrigerator work without stopping due to the heat in the room?
Yes, if the room temperature exceeds +30...+35°C, the refrigerator may not cope with heat inflows and work almost without interruption. However, complete shutdown cycles should still occur, albeit rarely.
Is it dangerous if the compressor is hot to the touch?
Heating the compressor housing to 70-90°C is normal for a running unit. It is dangerous if it is so hot that it is impossible to touch it, or if there is a burning smell.
How long should the refrigerator rest between cycles?
The operating and resting time depends on the load and the temperature in the room. Typically the work cycle is 15-20 minutes, and the rest cycle is 10-15 minutes. A duration of operation of more than 40 minutes without a pause should alert you.
Will complete defrosting help if the motor does not turn off?
If the reason is ice freezing on the evaporator (which interferes with heat transfer), then defrosting for 24 hours can temporarily solve the problem. If after switching on the situation repeats, there is a technical malfunction.