The situation when a newly repaired refrigerator hums for days on end, causing panic in the owner, occurs frighteningly often in the practice of service centers. It would seem that you paid the money, the technician replaced compressor or refueled freon, and the equipment should work like a clock, but reality makes its own adjustments. Instead of silence and periodic pauses in the operation of the unit, you hear the continuous hum of the motor, and inside the chamber the temperature may be either insufficient or, conversely, excessive.
Continuous operation of the engine without entering rest mode is a critical signal, ignoring which can lead to failure building expensive assemblies in just a few days or weeks. Unlike the normal mode, where on and off cycles alternate, a continuous cycle means that the control system does not receive the necessary data or is physically unable to achieve the set parameters. If your refrigerator, after service intervention, works without interruption for more than 24 hours, this is not the norm for most household models, with the exception of the period of initial cooling of an empty chamber.
The reasons for this behavior may be hidden as in trivial configuration errors, as well as in serious defects made during the recovery process. Sometimes the problem lies in a leaky circuit, and sometimes in incorrect calibration of the electronics. Understanding the nature of the malfunction will help you competently build a dialogue with the service department or, having the skills, eliminate the defect yourself.
Errors when filling with refrigerant and evacuation
One of the most common reasons why a refrigerator Indesit, Atlant or any other model does not turn off after repair is a violation of technology gas stations refrigerant. If the technician has not filled in enough freon, the pressure in the system drops and the compressor wears out, trying to compensate for the lack of refrigerant to achieve the desired temperature. In this case, the evaporator may only be partially covered with snow, and the cold in the chamber will be weak.
The opposite situation, when an excess amount of gas is pumped into the system, also leads to continuous operation, but is accompanied by overheating of the condenser and possible water hammer in the compressor. In addition, a critical step is to evacuate the system: if air or moisture remains in the circuit, this disrupts the thermodynamic cycle. Moisture can freeze in the capillary tube, creating an ice plug that blocks circulation, causing the motor to hum in vain.
- 🔍 An insufficient amount of freon causes the motor to operate without reaching the target temperature.
- 🔍 The presence of air in the system disrupts heat transfer and causes the unit to overheat.
- 🔍 An ice plug in the capillary completely blocks the refrigerant flow, simulating a leak.
⚠️ Attention: An attempt to independently refuel the refrigerator without a pressure gauge station and scales often leads to the final failure of the compressor. The pressure in the system depends on the ambient temperature and the type of refrigerant.
The quality of the refrigerant used also plays a role. If gas with impurities or inappropriate labeling was used (for example, R134a instead of R600a), the efficiency of the system drops sharply. In such cases, even working automation will not be able to correctly control the cycles, since the physical properties of the substance do not correspond to the calculated parameters of the system.
How to check the quality of refilling without instruments?
An indirect sign of correct refilling is the uniform heating of the condenser grille at the back of the refrigerator (about 2/3 of the height) and the complete thawing of the evaporator inside the chamber when the unit is turned off.
Malfunctions of the thermostat and temperature sensors
In old models of refrigerators, such as Biriusa or Soviet ZIL, the mechanical one is responsible for turning off the motor. thermostat. If after repair it has been replaced or adjusted, but the device is installed incorrectly, the contacts inside will not open. The capillary tube of the thermostat should fit tightly to the evaporator; if it is loosely secured or displaced, the sensor simply “does not feel” a real decrease in temperature in the chamber.
In modern units with a system No Frost and electronic control, the role of mechanics is performed by temperature sensors (thermistors). Their resistance changes depending on the heating, and if the repairman damaged the wiring or installed a sensor or a faulty part incorrectly, the “brains” of the refrigerator receive false signals. The electronic control module continues to keep the compressor on, “thinking” that the chamber is still warm.
Often the problem lies in sticking contacts of the start relay itself or a defect in the control board, which physically cannot break the compressor power circuit. Diagnostics in this case requires testing the circuits and checking the resistance of the sensors at different temperatures.
Do not forget about calibration. After replacing the control unit or sensors, some models require entering the service menu to reset errors and calibrate readings. Without this procedure, the refrigerator may operate in emergency mode, ignoring commands to stop.
Problems with tightness and freon leaks
The most annoying situation for the owner is when, after an expensive repair, it turns out that the system is leaking again. If the technician did a poor job of soldering the connections or did not replace the drying filters, a new leak may occur in a short time. In this case, the refrigerator operates constantly, since the pressure in the circuit drops, and the refrigerant does not have time to cool the chambers to the specified level.
Leaks often occur at soldering points, especially if the wrong solder was used or the joint was not kept clean. Also, the weak point remains the factory seams, which could have been damaged during transportation or poor-quality previous sealing. Finding a leak is a labor-intensive process that requires the use of a leak detector or the method of immersion in water (for individual components).
Signs of a leak are often:
- ❄️ Weak or uneven cooling of the chambers when the engine is running.
- ❄️ Hot a compressor that works without stopping.
- ❄️ No characteristic hissing when the tube is punctured (with a complete leak).
If a little time has passed after the repair, and the situation has repeated, ask the service department to re-diagnosis for leaks under nitrogen pressure. This is the only reliable way to ensure the integrity of the circuit before refilling.
The effect of replacing a compressor on the operation of the system
Replacement compressor is a complex operation that requires not only technical skills, but also the correct selection of equipment. If a compressor with an inappropriate capacity is installed (too powerful or, conversely, weak), the system will not be able to reach balance. A motor that is too powerful can quickly freeze the evaporator, but due to the design of the capillary tube, it will not have time to remove heat, which will lead to frequent starts or continuous operation.
In addition, when replacing the motor, the circuit must be purged with nitrogen to remove combustion products of oil and metal shavings. If this step is skipped, microscopic particles can clog the capillary line or filter drier. This creates resistance to the freon current, similar to a leak, and the refrigerator begins to work without interruption.
| Symptom | Possible cause | Action |
|---|---|---|
| The compressor is hot, the cold is weak | Clogged capillary or filter | Replacing the filter, purging with nitrogen |
| The motor is cold, does not turn off | Lack of freon (leakage) | Searching for leaks, vacuuming, refilling |
| There is a humming sound, there is no start | Faulty start relay | Replace the relay or check the windings |
| Works constantly, the chamber is cold | Fault thermostat/sensor | Replacing the temperature sensor |
☑️ Check after replacing the compressor
It is also important to consider the type of oil and refrigerant. The use of mineral oil in a system designed for synthetic (or vice versa) can lead to stratification of the mixture and disruption of lubrication, which indirectly affects operating efficiency and temperature conditions.
Failures in the electronic control module
In inverter refrigerators and models with the system No Frost the electronic module is responsible for all processes. If after the repair (even if they changed not the electronics, but the mechanics) there were power surges in the network, a software failure could occur or the relay on the board might become “stuck.” In this state, the module simply does not send a signal to turn off the compressor.
Sometimes the problem is solved by completely rebooting the system. To do this, you need to turn off the power to the refrigerator for 15–20 minutes. If, after switching on, the operating logic is restored and the on/off cycles return to normal, then a software failure has occurred. If the situation repeats, the elements on the control board responsible for switching the power circuit are probably damaged.
Diagnostics of electronics requires special knowledge and equipment. Independent soldering of a board without a circuit often leads to aggravation of the problem, so if you suspect a module malfunction, it is better to contact a specialized specialist.
It is worth noting that in some models, after defrosting or repairing, the system may be forced to work longer than usual to restore the temperature, but this period should not exceed 2–3 hours.
Human factor and user settings
The reason is not always a breakdown. Often, after the technician arrives, the owner, wanting to get cold faster, sets the temperature regulator to maximum (for example, mode Super Freeze or number 7). In this mode, the refrigerator should not really turn off until it completes the fast freezing program. If you forget to switch the mode back, the unit will operate continuously, which will lead to freezing of food and waste of energy.
It is also worth checking the tightness of the door. If after repair the repairman does not close the door completely or damages the seal, warm air constantly enters the chamber. The temperature sensor detects the increase and does not allow the compressor to go into rest. Make sure that the door closes tightly and is not warped.
Other factors affecting operation:
- 🌡️ Installing the refrigerator too close to a wall or heat source (radiator, stove).
- 🌡️ Loading a large amount of warm food immediately after repair.
- 🌡️ Open the door for a long time while checking operation.
⚠️ Attention: In winter, if the refrigerator is in an unheated room (garage, balcony), the oil in the compressor may thicken and the sensors may not work correctly. Most manufacturers do not recommend operation at temperatures below +10°C.
Check the settings in the menu (if there is one). Sometimes the fan or defrost operating parameters go wrong, which indirectly affects the compressor operating cycle. Resetting the settings to factory settings (Factory Reset) often helps eliminate user software errors.
When you need to call the technician again
If you have checked all the settings, made sure the door is tight and given the refrigerator time to stabilize, but it continues to hum without a break for more than a day, this is a reason to call again. Symptoms are especially alarming when the inside of the chamber is either too cold (everything is frozen) or not cold enough, and the outside of the unit is hotter than usual.
The repair warranty usually ranges from 6 to 24 months, and a return visit under warranty should be free. Do not try to open sealed connections or change electronics yourself if you are not confident in your abilities, as this will void the warranty.
Remember that continuous operation of the refrigerator is an extreme mode for the compressor. The engine resource in this mode is exhausted many times faster, so a quick solution to the problem will save you money on the purchase of new equipment in the future.
Why does the refrigerator hum, but does not cool after filling with freon?
Most likely, an air lock has formed in the system or an ice capillary is clogged. It is also possible to leak immediately after refueling due to poor soldering. Evacuation and refilling is required according to the scale.
Can a new thermostat not work correctly?
Yes, if it is selected incorrectly (different temperature range) or if its capillary tube does not fit well to the evaporator. It is also possible that the part itself is defective, which requires replacement under warranty.
How long should the refrigerator work after repair for the first time?
The first cycle can last longer than usual - up to 3-4 hours, until the temperature in the entire volume of the chambers stabilizes and the refrigerant is distributed throughout the system. However, after this it must turn off.
Is it dangerous for the compressor to work without stopping?
Yes, this leads to overheating of the windings, destruction of the oil and jamming of the piston group. Long-term operation without interruption significantly reduces the service life of the motor.