You noticed that your refrigerator started to work in an unusual mode, making constant noise, even when it seemed Should there be a cycle of rest? A situation where the fan does not turn off can be caused by either simple icing or a serious malfunction in the control circuit. In most cases, the No Frost system, which uses forced air circulation, operates cyclically, but failures in sensors or mechanical obstacles can disrupt this algorithm.
Constant operation of the motor leads to overheating of the compressor and increased energy consumption, so you should not ignore this symptom. In this article, we will look in detail at why it hums fan, how to distinguish normal operation from a breakdown, and what steps to take to restore silence.
If you hear a continuous hum, the first thing you should do is listen to the nature of the sound. Sometimes this is not a breakdown, but a feature of the system’s operation after defrosting or loading warm products. However, if the noise does not subside within several hours, it is necessary to carry out diagnostics.
⚠️ Attention: Before any manipulations with electrical components, be sure to disconnect the device from the network to avoid electric shock.
The principle of operation of the No Frost system and the role of the fan
To To understand why fan does not stop, you need to understand the basic algorithm for how refrigerators work with the system. No Frost. Unlike the drip system, here cooling occurs due to the constant circulation of cold air. A fan, usually located in the freezer compartment or behind the back wall, forces air through the evaporator, distributing the cold throughout the entire volume of the chambers.
In normal operation, the motor turns on synchronously with the start of the compressor or according to a signal from the temperature sensor. As soon as the internal temperature reaches the set values, the controller must issue a stop command. If this does not happen, it means that the feedback circuit is broken or the actuator is stuck.
Modern models use complex electronic modules that read readings from several sensors. Temperature sensor in the evaporator and the sensor in the chamber can give conflicting signals if there is a malfunction, causing the system to think that the cooling is not effective enough and continue to circulate air.
It is important to note that in some models LG or Samsung the fan can run for some time after the compressor stops to “blow out” the remaining cold, but this period rarely exceeds 5-10 minutes.
Icing evaporator and blades
One of the most common reasons why fan does not turn off or works intermittently is ice freezing. The systems No Frost have an automatic defrost cycle, but if it is broken, ice begins to accumulate on the evaporator and can reach the fan impeller.
When the blades touch the ice, a characteristic cracking or hum occurs, and the airflow sensor may be blocked, preventing the system from understand that air circulation has stopped. As a result, the control module continues to supply voltage to the motor, trying to provide cooling.
- ❄️ Tightness failure: A loosely closed door or a damaged seal allows moist air to pass through, which instantly freezes.
- 🌬️ Drainage clogged: Water from defrosting does not leave, freezes at the bottom and grows upward, reaching fan.
- 🔥 Heating element malfunction: The heating element does not turn on during defrosting, and the ice does not have time to melt.
To check this version, it is often enough to completely manually defrost the refrigerator, leaving it turned off for day. If after turning on the problem disappeared, it means that the problem was precisely excess moisture and ice.
⚠️ Attention: Do not try to chip the ice with a knife or sharp objects - there is a high risk of damaging the evaporator tubes or fan blades, which will lead to expensive repairs.
Temperature sensor malfunctions and timer
The refrigerator electronics rely on sensor readings. If temperature sensor the evaporator is out of order and shows incorrect (low) values, the controller “thinks” that it is warm in the freezer and does not give a command to stop the fan. A faulty defrost timer behaves similarly, which can get stuck in cooling mode.
Diagnostics of these elements requires a multimeter. The resistance of the sensor changes depending on the temperature, and if its readings are out of range, the control module goes into emergency mode or continues to operate continuously. In some models Indesit or Atlant this may also be accompanied by blinking indicators on the panel.
How to check the sensor with a multimeter?
Remove the sensor, set the multimeter to resistance measurement mode (Ohm). At room temperature, a working sensor should show a certain resistance (usually several kOhms). Place the sensor in the freezer and the resistance should change. If there are no changes or the indication is “break,” the part is faulty.
Replacing the sensor is a simple procedure, but requires care when dismantling plastic panels. Often, along with the sensor, the wiring is also changed if it is frayed or oxidized.
Mechanical damage and wear of bearings
Sometimes the problem lies not in the electronics, but in the fan motor itself. Over time, the plain or rolling bearings wear out, the lubricant dries out, and the shaft begins to jam. In this state, the motor may hum constantly, trying to turn a jammed impeller, or run jerkily.
It is also worth checking the integrity of the blades. If one of them cracks or breaks off, imbalance, vibration and noise occur. In rare cases, a piece of debris may block rotation, but the electrical circuit remains closed.
To check, remove the back panel in the freezer (after turning off the refrigerator) and try to manually turn the blades. They should rotate easily and silently. If you hear a creaking sound or feel resistance, fan requires replacement.
| Symptom | Probable cause | Solution |
|---|---|---|
| Crackling during operation | Ice on the blades | Defrost 24 hours |
| Constant hum | Bearing wear | Replacement motor |
| Case vibration | Impeller imbalance | Fan replacement |
| Cyclic noise | Normal operation | No intervention required |
When replacing, it is important to select an analogue with identical geometric dimensions and electrical characteristics (voltage, current).
Problems with the control module
The most complex and expensive option is failure of the module itself control module. Control boards in refrigerators Bosch, Liebherr and other brands are susceptible to voltage surges. If a triac or relay that controls the fan burns out, it can “stick” in a closed state, constantly supplying power to the motor.
Visually, burn marks, blackened tracks or swollen capacitors are often visible on the board. However, sometimes the defect is hidden. In such cases, professional diagnostics or replacement of the entire board is required. Resoldering individual elements is possible, but does not always guarantee a long-lasting result.
If you notice that the refrigerator began to behave strangely after a thunderstorm or power surge, the likelihood of electronic failure increases dramatically. In this case, independent repair without a diagram and equipment is practically impossible.
Diagnostics and procedure
Before calling a technician, you can carry out a number of simple steps that will help localize the problem or even solve it without cost. Start by visually inspecting and listening to the unit.
- 👂 Listen: Open the door - the fan should stop (in most models). If it continues to work when the door is open, the door sensor may be faulty or the button is stuck.
- 🧊 Inspect: Look into the freezer. Is there a “coat” of ice on the back wall? This will indicate problems with defrosting.
- 🔌 Reboot: Unplug the refrigerator for 15-20 minutes. This will clear errors in the electronic module.
If simple measures do not help, proceed to a more in-depth diagnosis. Check the door seals - if they allow air to pass through, the system will work for wear, trying to compensate for heat inflows.
☑️ Primary diagnostic checklist
It is also important to take into account the age of the equipment. If your refrigerator is more than 10 years old, wear and tear on the compressor and fan is a natural process, and repairs may not be economically feasible compared to buying a new model.
When you need to call a technician
There are situations where independent intervention can only worsen the situation. If you do not have the skills to work with power tools and a multimeter, it is better to entrust the repair to professionals. This is especially true when replacing a compressor, refilling with freon or repairing an electronic board.
Call a specialist if:
- 🛠️ Replacement of spare parts is required: You need an original motor or sensor that is difficult to find in retail.
- 💧 There is a freon leak: If you heard during defrosting hissing or you smell oil, the system is depressurized.
- ⚡ The board has burned out: Electronic repair requires soldering and knowledge of circuit design.
⚠️ Attention: Do not try to solder the tubes or change the compressor yourself without a vacuum pump and a pressure gauge station - this will lead to rapid breakdown of the refrigerator.
A professional technician will conduct a full diagnostic, check the compressor current consumption, the pressure in the system and the integrity of the electrical circuits. This will allow you to accurately determine the cause and eliminate it with a guarantee.
Fault prevention
In order for fan and other components of the refrigerator to serve for a long time, it is important to follow the operating rules. Defrost the unit regularly (even the No Frost system is recommended to be defrosted once a year for prevention), keep the condenser at the back clean and do not load warm foods into the chamber.
It is also worth checking the condition of the seals and wiping them on time. Cleanliness and proper installation of the refrigerator (distance from the wall of at least 5-10 cm for ventilation) will prolong the life of your assistant.
Following these simple rules will avoid unpleasant surprises in the form of constant noise and food spoilage.
Frequently asked questions (FAQ)
Is it normal for the fan to work immediately after turning on the refrigerator?
Yes, this is absolutely normal. After switching on or defrosting, the fan runs continuously until the set temperature in the chambers is reached. This process can take from 2 to 6 hours depending on the model and load.
Why does the fan stop when you open the door?
Most modern refrigerators have a door opening sensor. When you open the chamber, the light comes on and the fan turns off to avoid blowing cold air out and creating drafts. If it does not stop, check the sensor button.
Is it possible to operate the refrigerator if the fan is humming, but it freezes?
For a short time, it is possible, but not recommended. Constant operation of the fan leads to overheating of the motor windings, drying out of the lubricant and eventual combustion of the motor. In addition, this increases energy consumption. It is better to eliminate the cause of the noise.
How often should the fan be changed?
The service life of the fan is usually 5-10 years or more. It does not require scheduled replacement, only when noise, vibration or a complete stop occurs. The quality of the part and operating conditions (humidity, temperature) directly affect the service life.