Sudden silence in the kitchen, where the refrigerator used to hum smoothly, is often the first signal of a serious breakdown. When it stops working compressor, this means not just a lack of cold, but a potentially expensive repair or the need to replace the entire unit. Many owners of household appliances mistakenly believe that the mechanism has simply “worn out” over time, but in reality, the process of failure of the heart of the refrigeration system almost always has a specific physical cause.
Understanding exactly how this destructive process occurs will help you notice alarming symptoms in time and, possibly, save expensive equipment. Winding combustion electric motor is the final stage of a chain of events that could begin long before the appearance of smoke or the characteristic burning smell. In this article, we will analyze in detail the mechanics of failure so that you can distinguish natural wear and tear from a critical malfunction.
Modern models of refrigerators, be it Liebherr, Atlant or Bosch, use similar operating principles of compressors, however, their sensitivity to external factors may vary. Ignorance of the basic principles of thermodynamics and electrical engineering often leads to the fact that users miss the moment when the situation could still be corrected by preventive measures or by replacing cheap components.
Thermal destruction of winding insulation
The main reason why a compressor burns out is a critical excess of the operating temperature inside the motor housing. The electric motor is designed to operate in a certain thermal regime, which is ensured by the circulation of refrigerant and oil. When temperature conditions is violated, the varnish covering the copper wire of the stator windings begins to lose its dielectric properties.
Initially, the insulating layer softens, and then it completely melts. At this moment, a turn-to-turn short circuitappears between the turns of the coil. The winding resistance drops, the current increases sharply, which leads to even more intense heat generation. This process has an avalanche-like nature: the stronger the heating, the greater the current, and the faster the motor burns out.
The result of this scenario is either the blown fuse (if it is provided for in the design), or the complete burnout of the windings with the formation of a conductive deposit inside the housing. In some cases, especially in inverter models of brands like Samsung or LG, the electronics can detect a current anomaly and block the start, but in older models with asynchronous motors the result is most often the same - a short circuit.
⚠️ Attention: The characteristic smell of burnt plastic or scorched wiring emanating from the rear grill of the refrigerator is a direct sign of the onset of thermal destruction of the insulation. Ignoring this symptom is guaranteed to lead to compressor failure.
It is important to understand that a single overheating may not kill the motor instantly, but it significantly reduces the service life winding insulation. Repeated cycles of overheating and cooling make the varnish brittle, it cracks and crumbles, which ultimately provokes a short circuit even during normal operation.
The influence of power surges and the quality of the electrical network
The electrical network in our homes is rarely ideal, and that is Voltage instability often becomes a catalyst for breakdown. The refrigerator compressor is a large energy consumer and requires significant starting current to start it. If the network is chronically low voltage, the electric motor tries to compensate for the lack of power by increasing the current consumed from the network.
Working in this mode is similar to a car trying to drive uphill in a high gear: the engine works at the limit, gets very hot and does not develop the required speed. In such conditions, the starting relay can keep the starting winding on for a long time, trying to start the rotor, which inevitably leads to its burnout.
- 🔌 Sudden voltage surges above 240-250 Volts cause insulation breakdown and instant combustion.
- 📉 Long-term low voltage (less than 190 Volt) leads to thermal overload and destruction of the windings.
- ⚡ Pulse interference from the operation of powerful neighboring equipment (welding, machine tools) can damage the electronic control board.
Voltage surges are especially critical when the compressor is turned on. If a jump occurs at this moment, the current load on the relay contacts and the motor winding increases many times over. In inverter systems, where the start-up is smooth, the risk is lower, but their sensitivity to the quality of the input signal is higher.
⚠️ Attention: The use of cheap Chinese stabilizers with a low response speed may not save, but harm the equipment. To protect the refrigerator, not only the power of the stabilizer is important, but also the speed of its response to changes in input voltage.
Mechanical jamming and water hammer
The compressor does not always burn out due to electrical reasons. The mechanical part is also subject to wear and tear. One of the most dangerous situations is jamming of the piston group. The reason may be a lack of oil, foreign objects entering the cylinder, or scuffing on the cylinder surface due to the exhaustion of its service life.
When the piston jams, the electric motor rotor cannot make a single revolution. However, the start relay applies voltage to the start winding in an attempt to move the shaft. The current in this winding reaches maximum values, and it burns out in a matter of seconds or minutes. In some cases, the starting relay itself burns out, which “sticks” in the closed state.
Another dangerous mechanical scenario is hydraulic hammer. This happens when liquid refrigerant or oil enters the compressor cylinder instead of gaseous freon. The liquid is not compressed, and during the upward stroke of the piston, enormous pressure is created, which can break the valves, connecting rod, or even pierce the cylinder body.
What happens during a hydraulic shock?
With a hydraulic shock, the compression energy is not absorbed by the gas, but is transferred to mechanical elements. This is often accompanied by a loud knocking or cracking noise. If the compressor survives the shock, its valves may be deformed, which will lead to a drop in performance and constant overheating, which will ultimately still lead to burning of the windings.
Often, mechanical problems are accompanied by a characteristic hum or knocking. If you hear that refrigerator hums louder than usual, but does not produce any cold, this may mean that the compressor is running "idle" or is trying to overcome mechanical resistance.
Faulty start relay and thermal protection
The starting relay and thermal protection relay (thermal protection) are the main guards of the compressor. Their task is to ensure that the engine starts correctly and turns off the power if it overheats. However, if these components fail, they themselves become the cause of the death of the motor.
The most common situation is when the contacts of the starting relay welded or stick in the closed position. In this case, the starting winding, which should only work for a fraction of a second at start, remains energized constantly. Since it is not designed for long-term operation, it burns out very quickly.
The thermal relay, in turn, can “get tired” and stop opening the circuit when a critical temperature is reached. The bimetallic plate inside it deforms over time or becomes covered with soot, which disrupts heat transfer. As a result, the compressor heats up above the permissible limit, but the power does not turn off.
- 🔥 Sticking of the start relay contacts in the "On" position.
- 🌡️ Loss of sensitivity of the thermal relay to case overheating.
- 🔌 Contact failure in circuits leading to constant startup attempts (cycling).
Diagnostics of these elements often allows you to save the compressor if its windings are still intact. Replacing a relay is an inexpensive procedure that you can do yourself with basic skills. It is only important to choose the right analogue, since the relay parameters must strictly correspond to the engine power.
Problems with the cooling system and refrigerant
The compressor in the refrigerator is cooled by the refrigerant itself, which circulates through the system. If a freon leak occurs in the circuit, the compressor begins to pump rarefied gas or a mixture of gas and air. The lack of normal flow of refrigerant leads to the fact that the motor ceases to receive the necessary cooling.
In addition, when working with rarefied gas or in a vacuum (with a strong leak), the compressor works with increased load, trying to create the necessary pressure. This causes a rapid rise in temperature. In such conditions compressor combustion it is only a matter of time, usually from several hours to several days of continuous operation.
Another factor is system contamination. If moisture or oil breakdown products circulate in the circuit, they can form acidic compounds. These acids destroy the insulation of the windings from the inside, making it conductive. This is the so-called “acid burnout,” which often happens after poor-quality repairs when the system has not been flushed.
It is important to monitor the temperature of the tubes at the outlet of the compressor. If they are not just warm, but red-hot or to such a state that they cannot be touched, this is a sign of problems with heat transfer or a refrigerant leak.
Diagnostics and signs of impending failure
Before the compressor finally burns out, it usually gives signals. An attentive user can notice changes in the operation of the refrigerator long before a disaster. The first sign is often a change in operating mode: the refrigerator starts to turn on more often or, conversely, works longer than usual.
The second important marker is the body temperature. If the side walls or rear grille refrigerator become noticeably hotter than before, this indicates that the system is overloaded. You should also listen to the sounds: humming, clicking, humming with pauses - all these are symptoms of illness.
To accurately diagnose a compressor malfunction, you can use a multimeter. It is necessary to measure the resistance between the contacts of the windings. Normally, the resistance of the starting winding is higher than the working winding, and between the case and the contacts the resistance should be infinite (open).
| Check parameter | Normal value | Failure sign |
|---|---|---|
| Working resistance windings | 10-30 Ohm (depending on the model) | Open (infinity) or short circuit (0 Ohm) |
| Starting winding resistance | 30-100 Ohm | Significantly higher than normal or a break |
| Resistance to the case | Infinity (∞) | Any value (breakdown to the case) |
| Starting current | Short-term jump | Prolonged high current (jamming) |
☑️ Diagnostics before calling a technician
If the multimeter shows resistance between any contact and the copper tube (casing) equal to zero or several Ohms, the compressor can be considered burnt out with a breakdown to the casing. It is strictly prohibited to operate such a unit due to the risk of electric shock.
Prevention and extension of service life
To minimize the risk of compressor combustion, you must follow the operating rules. The main rule is not to put hot food in the refrigerator and not to open the door unless necessary. This reduces the load on the system and the number of switching cycles.
Regular defrosting (for No Frost systems this is also useful as a preventive measure) and cleaning the condenser at the back of the refrigerator from dust improves heat transfer. A clean condenser allows freon to transfer heat more efficiently, which reduces the temperature and discharge pressure, facilitating the operation of the compressor.
Using a high-quality surge filter or a voltage control relay (VCR) will protect equipment from surges in the network. The RKN is a small device that turns off the power if the voltage goes beyond safe limits, and turns it back on only after stabilization.
Is it possible to restore a burnt out one? compressor?
It is impossible to restore a burnt-out compressor at home. Rewinding the windings requires special equipment, vacuum drying and reassembly of the housing in the factory. It is economically more expedient to replace the entire unit or buy a new refrigerator, since the cost of overhaul is often close to the price of a new unit.
Why does a new compressor burn out after a month?
This happens if the replacement did not eliminate the root cause: the system was not flushed from acids, the filter-drier was not replaced, or moisture remained. Also, the cause may be incorrect refrigerant charging (wrong type or wrong volume), which causes overheating.
It hums, but does not start - is it burnt out?
Not necessary. A humming sound without starting often indicates a stuck mechanical part or a faulty start relay. If the hum stops after 5-10 seconds and a click is heard, the thermal protection is activated. In this case, the motor may be intact, but requires replacing the relay or “wedging.”
What is the service life of the compressor?
The average service life of a modern compressor is 10-15 years. However, under unfavorable conditions (voltage surges, overheating, frequent power outages), it can fail much earlier. Inverter models last longer due to the absence of starting currents.
Is it dangerous to use a refrigerator if you smell a burning smell?
Yes, it is extremely dangerous. A burning smell indicates melting of the insulation of wires or components inside the compressor. This may cause a short circuit and fire. You must immediately disconnect the refrigerator from the network and call a technician for diagnostics.