The situation when the refrigerator hums and does not turn onis one of the most stressful for the owner, since the safety of the products is at risk. The hum usually comes from compressor, which is trying to start, but cannot overcome the internal resistance or does not receive the necessary impulse from the trigger mechanism. This hum is the sound of a running electric motor, which is clamped in the grip of a mechanical or electrical malfunction.
Primary diagnostics requires your attention: it is important to distinguish between the hum of a working unit from an intermittent hum with clicks or a heavy hum, followed by silence after 10-15 seconds. If you hear a relay click, followed by a hum and then a click again, this is a classic sign that the starter winding is not firing or the piston is stuck. At this moment current in the circuit increases sharply, which can lead to overheating of the wiring if you do not disconnect the device from the network.
Do not panic if refrigerator stopped freezing, but makes sounds: in many cases the problem is solved by replacing an inexpensive starting device or eliminating simple operating errors. However, ignoring symptoms such as overheating compressor housings or frequent clicking noises can lead to burnt out motor windings, which will require complex and expensive repairs. Next, we will look at the main reasons why equipment makes sounds but does not start the cooling cycle.
Power supply problems and power surges
The first thing you need to exclude before sinning to break compressor is the quality of the supplied electricity. If voltage the power drops below the acceptable threshold (usually 190-200 volts), the engine may hum while trying to start, but not have enough power to turn the shaft. In such cases starting relay it may try to turn on the engine repeatedly, making characteristic clicks, but a full start does not occur.
Instability of power supply is often found in suburban areas houses or other areas of the city where wear and tear electrical networks is high. If you notice that the refrigerator is humming during peak network load hours (in the evening), the problem may lie in low voltage. To protect equipment in such conditions, it is necessary to use voltage stabilizerwhich will level the indicators to normal.
Bad contact in a socket or extension cord can also cause buzzing and heating of the plug. Oxidized contacts create high resistance, due to which less energy is supplied to the engine than is required to start. Check whether the plug fits tightly in the socket and whether it heats up during operation.
⚠️ Attention: Using cheap surge protectors or extension cords with thin wires to connect powerful refrigerators is strictly not recommended. This creates a risk of fire and false diagnosis of breakdown of the refrigerator itself.
Malfunction of the start relay and thermal protection
The most common reason that the refrigerator hums and does not turn onis the failure of the start protection relay. This small device, which is mounted on the side or rear of the compressor, is responsible for sending an impulse to the starting winding of the engine at the moment of start. If the contacts inside the relay are burnt or stuck, the engine will hum, but the shaft will not budge.
Inside the relay there is also a thermal protection (thermal relay), which opens the circuit when the windings overheat. If the refrigerator hums for 10-20 seconds, and then there is a click and there is silence for several minutes, this is the work of thermal protection. It saves the motor from burning out by breaking the chain until it cools down. After cooling, the cycle repeats: click, buzz, click again.
You can replace the relay yourself if you have skills in working with electrical equipment and a suitable one screwdriver. Usually the relay is simply removed from the compressor pins and disconnected from the wires. It is important to buy a part with exactly the same markings as the burnt one, since the parameters starting current are different for different compressor models.
Compressor jamming (mechanical failure)
The most unpleasant scenario in which the refrigerator is hummingbut does not start is mechanical jamming of the compressor piston group. This can happen due to the exhaustion of the life of the rubbing parts, lack of lubrication, or, more often, due to working with impurities or the presence of moisture in the system. In this case, the motor shaft is physically blocked. freon with impurities or when there is moisture in the system. In this case, the motor shaft is physically blocked.
When you try to start, you hear a very loud, strained hum, which can last until the thermal relay is activated. The motor is trying to turn over, but a mechanical obstacle prevents it from doing so. In such cases current in the windings it increases instantly, which leads to rapid heating of the compressor housing. If you touch it (carefully!), it will be very hot.
There is a method of “wedging” the compressor by applying increased voltage or using a special device (transformer), but doing this at home dangerous is not always effective. Often the only solution is to replace the entire compressor, which requires calling a technician with equipment to evacuate the system and refill refrigerant.
Is it possible to resuscitate a jammed compressor?
In some cases, the method helps “tapping” a rubber mallet on the body of a working (trying to work) compressor to move the pistons out of place. However, this is a temporary measure with a low success rate and the risk of finally finishing off the unit.
Malfunction of the starting capacitor
In many modern models of refrigerators, especially with two-phase motors, starting capacitoris responsible for starting. If this element fails (dries out or loses capacity), the phase shift necessary to create torque does not occur. As a result, the motor hums, but cannot start rotating.
A visually faulty capacitor often has a swollen housing or traces of electrolyte leaks, although sometimes there are no external signs. You can check it only using a multimeter with a capacity measurement function or by replacing it with a known good one of similar capacity. Using a capacitor with other parameters may lead to improper operation of the engine.
Replacing a capacitor is an inexpensive and technically simple procedure. The main thing is to observe the polarity (if the capacitor is electrolytic) and voltage. The working part is always indicated on the body voltage (for example, 250V or 450V), and the new element must have an equal or greater value.
☑️ Diagnosis of the capacitor
Table: Diagnostics by sound signs
To more accurately determine the cause of the malfunction, pay attention to the nature of the sound and the behavior of the indicators. Below is a table to help classify symptoms.
| Symptom | Probable cause | Required actions |
|---|---|---|
| Humming for 5-10 seconds, then a click and silence | Thermal protection has tripped, problem with the start relay | Replacement start-up protection relay |
| Strong humming, case heating, no click | Compressor jammed or interturn short circuit | Call a technician, compressor replacement is possible |
| Quiet hum, refrigerator does not freezes | Freon leak or clogged capillary tube | Pressure diagnostics, leak search |
| Humming and vibration turning into knocking | Breaking the compressor suspension or touching tubes | Adjusting the position of tubes, replacing shock absorbers |
Problems with wiring and contacts
Sometimes the reason that the refrigerator is humminglies not in the unit itself, but in the supply line. Loose screws on a terminal block inside the refrigerator or at an outlet can cause arcing and voltage drops. This is especially true for old wiring, where the aluminum could “float” under load.
Pay attention to the condition of the plugs sockets. If they turn black or the plastic melts, the contact is broken. In this case, the current flows with difficulty, causing hum and heating. It is necessary to clean the contacts or replace the socket/plug. It is also worth checking the integrity of the power cord along its entire length for kinks or damage to the insulation.
Inside the refrigerator, the wires can be chewed by rodents (relevant for equipment stored in the country) or they can rub against the vibrating part of the case. Any short circuit to the housing or open circuit will lead to incorrect operation electric motor. A visual inspection of the internal wiring with the back cover removed often helps to find obvious defects.
⚠️ Attention: Carry out all work on checking the wiring and replacing electrical components ONLY with the refrigerator completely disconnected from the network. Residual voltage in the capacitors can be dangerous.
What to do if the compressor overheats
If you notice that during the humming process the compressor housing (the black “tank” at the back) becomes scalding hot, this is an alarm. Overheating indicates that the engine is running in short mode short circuit of the rotor or stator, or that it is jammed. Prolonged operation in this mode is guaranteed to lead to burnout of the windings.
In some cases, overheating is caused by insufficient ventilation. If the refrigerator is located close to the wall or in a niche without gaps, heat is not dissipated. In the hot season, this can provoke false alarms and buzzing. Make sure that the gap between the back of the refrigerator and the wall is at least 10-15 cm.
If the compressor is hot and humming, let it cool completely (1-2 hours) before turning it on again. If upon restart the situation repeats (humming, heating, shutdown), further attempts to turn on the device are useless and dangerous - a professional repair or replacement of the unit is required.
The influence of ambient temperature
Paradoxically, too low a room temperature can also cause it to turn on the refrigerator hums and does not turn on (or it turns on rarely and with problems). Most refrigerators are designed to operate in climate class SN-N-ST (from +10°C to +38°C). If the room is colder than +10°C (for example, on an unheated loggia in winter), the oil in the compressor becomes too viscous.
Thick oil creates enormous resistance at start-up. The engine hums, trying to turn the shaft, but cannot overcome the viscosity of the lubricant. In this case, the thermal relay may not give a start command at all, since the sensor inside the chamber “thinks” that it is already cold. However, if the start is initiated, the hum will be very heavy.
For operation in such conditions, class T (tropical) or ST (subtropical) equipment is required, or the installation of a freeze zone heater that will heat the thermostat and oil. Without this operation a conventional refrigerator in the cold will lead to rapid wear and tear.
Why can’t you turn on the refrigerator immediately after transportation?
If the refrigerator was transported lying down, oil could leak into the system. Turning on such a compressor will cause water hammer and jamming. You need to let it stand upright for at least 4-8 hours (preferably a day) before turning it on.
Is it possible to fix a refrigerator if it is humming with your own hands?
If the problem is in the start relay, capacitor or socket - yes, you can really do it yourself if you have basic tools. If the reason is a freon leak, a clogged system or jamming of the compressor itself, specialized equipment and the skills of a technician are required.
How long can a refrigerator hum before shutting down?
The normal hum cycle when trying to start should not last more than 10-15 seconds. After this, the thermal relay should operate. If the humming continues longer without a shutdown click, this is dangerous and requires urgent unplugging of the plug.
Why does a new refrigerator hum loudly when first turned on?
When first started, the system is filled with refrigerant, and the compressor works to the limit to create a pressure difference. This may be accompanied by increased humming and gurgling. If after 2-3 hours of operation the noise does not subside, it is worth checking the levelness of the installation with the feet.
Is it dangerous to continue using a refrigerator that is humming?
A short humming noise upon startup is normal. But if the hum is constant, intermittent with clicks, or is accompanied by a lack of cold, operation is dangerous. This can lead to a wiring fire or complete breakdown of an expensive compressor.