A sudden loss of cold in the refrigerator is always stressful for the home cook, because food supplies are at risk. Most often, the cause of a breakdown is the failure of the motor-compressor, which is the “heart” of the entire cooling system. You can understand that the problem lies in this particular unit by the characteristic signs: the unit hums, but does not cool, or is completely silent, although the indicators are on.
Before calling a technician or buying a new refrigerator, it makes sense to carry out the initial diagnostics yourself. This will help save time waiting for a specialist and give an understanding of the scale of the problem. In this article, we will analyze proven methods for identifying malfunctions compressor, using both simple visual methods and professional tools.
It is worth noting that the absence of cold does not always mean the death of the engine. Sometimes the start relay or thermostat is to blame. However, if the diagnostics show a break in the windings or an interturn short circuit, then repair is most often impractical and the entire assembly will need to be replaced. Let's figure out how to distinguish one problem from another.
Primary visual diagnostics and sound analysis
The first step in identifying a malfunction should always be an external inspection and listening to a running (or trying to start) unit. Plug in the refrigerator and listen carefully to the sounds it makes. A working one compressor works with a smooth, quiet hum, which is periodically interrupted when switched off.
If you hear a loud metallic clanging, clicking or humming that ends abruptly after a few seconds, this is an alarming signal. These sounds often indicate that the engine is trying to start but cannot overcome resistance or lacks lubrication. In some cases, you can hear the characteristic gurgling of the refrigerant, which also requires attention.
⚠️ Attention: If you hear a loud cracking sound when you turn it on or see sparks in the area of the back wall, immediately unplug the device! Further operation may lead to a fire in the wiring.
It is also important to check the temperature conditions. If the motor hums continuously, without turning off for hours, and the temperature in the chambers does not drop below +10 degrees, this indicates a loss of performance. The engine is running empty, or there is a freon leak, or the system is not sealed.
Checking the starting relay and electrical circuit
Before sinning on the motor itself, it is necessary to exclude damage to the starting relay. This small element is responsible for supplying a starting pulse to the motor winding. If the relay is “stuck” or burnt out, the compressor simply will not receive a command to start, although electricity is supplied to it.
To check the relay, it must be carefully removed from the contacts of the compressor. Visually inspect the housing for melting or cracks. If there are no outward defects, you can shake the relay near your ear: if it rattles inside, it means that the core or coil has fallen apart, and the element requires replacement.
- 🔌 Disconnect the refrigerator from the power supply before any manipulations.
- 🔧 Remove the protective cover at the back of the unit to gain access to the motor.
- 📏 Check the relay contacts for oxidation or carbon deposits.
- ⚡ Make sure that the wires going to the terminals are securely fixed.
Often owners Atlant refrigerators or Indesit face oxidation of the contacts at the junction of the relay and the motor. This creates additional resistance, and the current cannot pass in the required volume. Cleaning the contacts with fine sandpaper sometimes solves the starting problem.
Diagnostics of the compressor with a multimeter (tester)
The most accurate way to check is to measure the resistance of the windings using a multimeter. This device allows you to determine the integrity of the electrical circuit inside the engine. To carry out the test, switch the multimeter to the resistance measurement mode (Ohm) to a limit of 200 Ohm.
There are three terminals (contact pins) on the compressor body. They usually form a triangle. You need to “ring” them in pairs by touching them with the probes of the tester. Normal resistance readings vary depending on the power of the motor, but the general picture should be as follows: there should be a certain resistance between the top and left contact, as well as between the top and right.
The most important thing is that the sum of the resistances of the two smaller values should equal the largest. For example, if between contacts A-B there are 20 Ohms, A-B 15 Ohms, then between B-C there should be about 35 Ohms. If you see one (infinity) or zero on the screen, then there is a break or short circuit.
| Measurement parameter | Normal value | Fault value | Diagnosis |
|---|---|---|---|
| Starting winding resistance | 30-40 Ohm | ∞ (infinity) | Open circuit |
| Working winding resistance | 10-20 Ohm | 0 Ohm | Short circuit |
| Resistance between case and contacts | ∞ (infinity) | Any number | Breakdown to the body |
| Thermal relay (contacts) | 0 Ohm (closed) | ∞ (open) | Relay burned out |
Pay special attention to checking for breakdown. Press one multimeter probe to any contact, and the second to a copper tube or a cleaned area on the motor body. The device should show infinity. If there is at least some value, it means that the insulation is broken, and operating such a unit is deadly.
☑️ Check with a multimeter
Measure the starting current strength
If the winding resistance is normal, but the refrigerator still does not work or knocks out the machines, it is necessary to measure the strength of the starting current. This procedure requires the use of special current clamps. It allows you to understand whether the engine has enough power to start and whether it “eats” too much electricity.
To take measurements, current clamps are placed on one of the power wires going to the compressor when the refrigerator is turned on. In the first seconds, the current jumps sharply - this is the inrush current. For household models, the norm is considered to be a value in the range from 3 to 6 Amperes.
If the clamps show a value significantly higher than the norm (for example, 10-15 Amperes) and immediately knocks out the plugs, it means that something happened in the windings interturn short circuit. In this case, the engine creates a powerful magnetic field, but does not rotate, but simply heats up. Repair in this case is impossible, only replacement.
⚠️ Attention: Work with current clamps is carried out under a voltage of 220 Volts. Be extremely careful not to touch exposed wires with your hands and use dielectric gloves.
Low inrush current is also not a good sign. If the device shows 1-2 Amps, this may indicate that the compressor is “stuck” mechanically, and the shaft simply cannot turn, despite the supply of energy.
Checking pressure and performance
Electrical service is not a guarantee of the operation of the refrigerator. The engine may hum, consume current, but not pump freon. A pressure gauge station is used to check performance. This method is more complex and requires special equipment.
A hose with a pressure gauge is connected to the service fitting (located on the compressor body). When starting up a working unit, the pressure gauge needle should quickly move into the red zone (positive pressure). If the pressure rises very slowly or stays the same, it means that the valves inside the piston group are worn out or broken.
Why does the compressor heat up?
The compressor can heat up to 90 degrees during operation - this is normal for some models. However, if it is so hot that it is impossible to touch it, and the refrigerator does not freeze, then most likely the circulation of the refrigerant is impaired or the motor is idling due to broken valves.
It is also worth checking the outlet pipe. On a working, working compressor, the discharge tube (the one that goes into the condenser) should be hot. If it is cold or warm, and the engine is running, it means there is no compression. This often happens in old models Biryusa or Zil after many years of operation.
Typical faults and their symptoms
Summarizing the above, we can identify several main failure scenarios. Understanding the symptoms will help you make a diagnosis faster. The problem does not always lie in the very “heart” of the refrigerator; sometimes it is enough to replace a cheap part.
- 🔥 Overheating: The motor is hot, it smells like burnt insulation, the thermal protection is triggered. Reason: bearing wear or interturn short circuit.
- 🔇 Silence: The refrigerator is on, the light is on, but there is silence. Reason: open circuit, burnt out relay or complete break in the motor windings.
- 🔊 Humming without cooling: The motor runs constantly. Reason: freon leak, clogged capillary tube or loss of compression.
It is important to understand that the compressor life is limited. The average service life is 10 years. If your unit is more than 15 years old, and it has begun to act up, it will be cheaper and more reliable to replace it with a new one than to spend money on expensive repairs of an old motor.
Frequently asked questions (FAQ)
Is it possible to replace the compressor on a refrigerator yourself?
Theoretically, yes, if you have the skills to work with a blowtorch, a vacuum pump and a gas station. However, without special equipment, it will not be possible to fill the system with freon and seal the tubes efficiently. It is better to entrust this to professionals.
How much does a new compressor for a refrigerator cost?
The price depends on the brand and power. For domestic models (Atlant), the cost of the unit starts from 3000-4000 rubles. Imported compressors (Danfoss, Embraco) can cost from 6,000 to 12,000 rubles and more, not counting the cost of installation work.
Why does the refrigerator not freeze after replacing the compressor?
There may be several reasons: poor-quality soldering (oxide remains), undercharging or overfilling freon, as well as possible blockage in the system, which was not eliminated during replacement. A new compressor could also fail due to a defect or a violation of the installation technology.
Is it possible to use a used compressor?
Using refurbished or used compressors is a lottery. Their resource has already been exhausted, and there is a high risk of repeated breakdown in a short period of time. Savings in this case are doubtful, since replacement work is expensive.