Failure of the cooling system is always stressful for the owner of household appliances, since food supplies are at risk. When you open the door and see that it’s warm inside, and you can’t hear the characteristic hum of the motor, the question arises: what exactly happened? Compressor It is the heart of the refrigeration unit, and its stop most often indicates a serious malfunction that requires immediate intervention.
It is important to understand that the refrigerator ceases to perform its function for a reason. If motor it burns out, the refrigerant stops circulating through the pipes and no cold is produced. However, before sounding the alarm, it is necessary to carry out initial diagnostics to exclude trivial problems with electricity or the thermostat that simulate a motor breakdown.
In this article we will analyze in detail the physical processes occurring inside the camera when the main unit fails, and we will explain how to distinguish a burnt out winding from other problems. You will find out why starting relay it may click, what to do if the engine hums but does not start, and whether it is worth trying to restore the equipment on your own.
The principle of operation of the system when the main unit fails
To understand what is happening inside, when compressor fails, you need to remember the basic principle of operation of the refrigerator. The motor compressor compresses the refrigerant gas, turning it into a liquid under high pressure. This liquid passes through the condenser, cools and enters the evaporator, where it turns into gas again, taking heat from the chamber.
If electric motor burnt out, this cycle is interrupted instantly. The gas stops compressing, the pressure in the system equalizes, and heat exchange stops. The temperature inside the chambers begins to rise, approaching room temperature. At this moment thermostat continues to send a signal to start, but due to an open circuit or short circuit in the motor windings, no reaction occurs.
In some cases, when the starting winding burns out, you You may hear periodic clicking sounds. This works thermal protection relaywhich tries to start the motor, gets an overcurrent and opens the circuit. After some time, the relay cools down and tries to start the unit again, creating a characteristic cyclic sound.
⚠️ Attention: If you smell burning or see sparking in the back of the refrigerator, immediately unplug the appliance. Further attempts to turn on may lead to fire of the wiring or melting of plastic elements.
Operation of the system without a working compressor is reduced to passive heating of the contents. Nothing cooling happens, regardless of what temperature the regulator is turned up to. The refrigerant simply stands in the tubes without participating in heat exchange.
Symptoms and signs of motor winding combustion
Diagnostics of the malfunction begins with visual and auditory analysis. The first sign that motor has burned out is the complete absence of vibration of the housing when the thermostat is running. If you put your hand to the back wall or side and do not feel the characteristic slight trembling, this is a bad sign.
The second important symptom is condition start relay. If, when you turn on the refrigerator, you hear a loud click, followed by a hum that lasts 3-5 seconds, and then a click again, the rotor is most likely jammed or the starting winding is burned out. The motor tries to jump off, but it does not have enough strength to turn the shaft.
The third sign is the smell. When winding insulation burns, a specific smell of burning wiring or varnish often appears. It may be barely noticeable if the breakdown has occurred recently, but if you stand for a long time with the appliance plugged in, the smell becomes distinct.
It is also worth paying attention to the temperature of the condenser (grid at the back). If the compressor tries to work, but does not start due to an interturn short circuit, the tubes may heat up unevenly or remain cold, while the compressor itself will be hot. motor housing will be red-hot.
Diagnostics with a multimeter: checking resistance
To accurately determine the condition windings you will need a multimeter. This is the most reliable way to understand whether the compressor has completely burned out or the problem is in the starting equipment. Before starting work, be sure to disconnect the refrigerator from the power supply!
Remove the protective casing from the compressor and disconnect the starting and thermal relays. You will see three pins on the motor contacts. They are usually arranged in a triangle. Your task is to ring pairs of contacts and measure resistance.
Normal resistance values for a working compressor vary within the following limits:
- 🔌 Between the common contact and the working winding: from 10 to 30 Ohm
- 🔌 Between common contact and starting winding: from 30 to 90 Ohm
- 🔌 Between the working and starting winding: the sum of the two previous values
If the multimeter shows infinity (one on the left or OL), it means in the winding break. If the device shows zero or very close to zero, a short circuit has occurred. In both cases, the compressor is considered burnt out and requires replacement.
⚠️ Attention: Never check the resistance until the capacitor in the circuit (if any) is discharged, and make sure that the multimeter probes are working properly. An error in measurements can lead to a false diagnosis.
It is also necessary to check the breakdown on the housing. One multimeter probe is placed on the contact, and the other on the copper tube or unpainted part of the compressor housing. The device should show infinity. If there is at least some resistance value, it means that the insulation is broken, and engine is dangerous for use.
The role of the starting relay and thermal protection
Often owners blame the compressor, when in fact the problem lies in starting relay. This small device is responsible for sending an impulse to the starting winding to start the rotor. If the relay is stuck or burnt out, the motor will not receive the desired push.
Thermal protection (tablet) prevents overheating of the windings. If it is faulty, it may open the circuit too early, preventing the compressor from even humming. Visually, there should be no traces of burning on the relay, and the core should not be loose inside.
How to check the relay without instruments?
Shake the relay near your ear. If you hear a ringing or knocking sound inside, it means the core is broken or the coil is cracked. Such a relay must be replaced, even if it looks intact on the outside.
Replacing a relay is a simple procedure that you can do yourself. However, if after installing a new relay the situation has not changed and compressor still does not start or the machine is knocked out, the problem lies deeper - in the motor itself.
It is important to select the relay strictly according to the markings indicated on the body of the old device or in the technical documentation of the refrigerator model. Universal relays are not suitable for all types motors, especially inverter ones.
Comparison of faults: compressor or freon?
Users often confuse a burnt-out compressor with a leak refrigerant. The symptoms may be similar: the refrigerator is not cooling. However, there are key differences that will help make the correct diagnosis without disassembling the unit.
When there is a freon leak, the compressor usually runs continuously, trying to gain temperature, but does not turn off. When the engine burns out, there is either silence or attempts to start are heard. The table below will help systematize your knowledge.
| Symptom | Compressor burned out | Freon leak | Thermostat is faulty |
|---|---|---|---|
| Operation sound | Silence or clicking | Constant hum | Silence or constant operation |
| Condenser temperature | Cold or warm (locally) | Warm only at the outlet | Hot throughout length |
| Cyclicity | No cycle (does not turn on) | Works without stopping | Does not turn off at all |
| Smell | Possible burning smell | Absent | Absent |
Thus, if motor is silent, and it’s warm inside, the probability of its breakdown is higher than the probability of leakage. A leak is characterized precisely by the endless operation of a serviceable but useless compressor.
Is it possible to restore a burnt-out motor?
The issue of repairing a burnt-out compressor often causes controversy. Theoretically, it is possible to rewind the windings, but in practice this is not economically feasible. The cost of work and materials will be 70-80% of the price of a new one unit, and the quality of such rewinding will be lower than the factory one.
Factory compressors are sealed in a sealed housing. To rewind it, it must be opened, which breaks the seal and requires subsequent evacuation of the system and refilling with freon. This is a complex process that requires expensive equipment.
The only reasonable solution is to replace the compressor with a new one. It is important to take into account not only the dimensions, but also powerthe type of refrigerant (R134a or R600a) and the type of oil. Using an unsuitable compressor will lead to rapid failure of the system.
If you do not have the skills to work with soldering torches and pressure gauge stations, it is better not to try to replace the compressor yourself. Unprofessional soldering of tubes can lead to microcracks and repeated leakage in a month.
Checklist of actions in case of suspected breakdown
If you find that the refrigerator has stopped freezing, act consistently. Do not panic and do not try to immediately disassemble complex components without preparation.
☑️ Algorithm of actions in case of breakdown
First make sure that the problem is not in the electrical system at home. Then listen to see if the refrigerator makes any sounds. If the motor hums but does not start, let it cool for a couple of hours and try to turn it on again.
⚠️ Attention: Do not leave food in an idle refrigerator for more than 4-6 hours in a warm room. Transfer perishable foods to a cool place or use refrigerants.
If after cooling the situation repeats, and the test with a multimeter shows an open or short circuit, the compressor is considered faulty and requires replacement. Further operation in this mode is impossible.
Is it possible to temporarily start a refrigerator without a compressor?
No, this is impossible. The compressor is the only element that creates pressure for the circulation of freon. Without it, the refrigerator turns into an ordinary cabinet.
How much does it cost to replace a burnt-out compressor?
The price consists of the cost of a new unit, consumables (freon, oil, filter) and the work of a technician. On average, this ranges from 30% to 60% of the cost of a new refrigerator.
Why does the compressor burn out?
The main reasons: power surges, overheating due to condenser contamination, thermostat malfunction (does not turn off the motor) or natural wear and tear after 10-15 years of service.
Is it dangerous to keep a burnt-out compressor plugged in?
Yes, it is dangerous. If an interturn short circuit has occurred, continued supply of voltage can lead to melting of the insulation, short circuit of the wiring and fire.