Sudden Stopping the operation of refrigeration equipment or the appearance of extraneous sounds often makes the owner think about the condition compressorwhich is the heart of the entire system. It is this unit that is responsible for circulating the refrigerant throughout the circuit, creating the necessary pressure for effective cooling of the chambers. If the engine stops starting or works intermittently, the food begins to deteriorate, and the temperature inside the unit is disrupted.
Before calling a technician or buying a new refrigerator, it is worth carrying out initial diagnostics, which in most cases allows you to identify the nature of the malfunction. Independent checking the functionality of requires a minimum set of tools and compliance with safety regulations, since we are talking about electric current and a complex mechanical assembly. Understanding the principles of operation the compressor will help you save time and money on repairs.
In this article we will examine in detail the stages of visual inspection, methods of electrical testing of windings and methods for identifying mechanical defects. You will learn how to distinguish a starting problem from a serious breakdown or wedge of the piston group.
Primary signs of compressor malfunction
The first stage of diagnosis is always careful observation of the behavior of the refrigerator. Faulty motor rarely fails without warning signals, which an attentive user can notice long before the unit completely stops. Often the problem lies not in the motor itself, but in accompanying elements, such as a thermostat or a start relay.
Pay attention to the cyclical operation: if the refrigerator turns on, hums for a few seconds and immediately turns off, this may indicate that the protection has tripped. Also, an alarming signal is constant operation without shutdowns, which indicates the impossibility of achieving the set pressure. In some cases, the engine may hum, but not start, producing a characteristic low-frequency hum.
⚠️ Attention: If you smell a burning smell or see sparking in the back of the refrigerator, immediately unplug the appliance from the power supply and stop any attempts at self-repair until the reasons are determined.
To systematize your observations, use the table of common symptoms that will help narrow down the search for the problem:
| Symptom | Possible cause | Probability of engine failure |
|---|---|---|
| The refrigerator does not turn on, there is no light | No power in the socket, break cord | Low |
| Buzzes for 5-10 seconds and clicks | Faulty starting relay or piston wedge | Medium/High |
| Works constantly, not cools | Freon leakage or loss of compressor performance | Average |
| Strong vibration and noise | Broken shock absorbers or worn bearings | Low (mechanics) |
Visual inspection and checking the temperature conditions
Before picking up the multimeter, you need to thoroughly inspect visual inspection the back of the refrigerator. Often the reason for inoperability lies in simple overheating or mechanical damage to the elements surrounding the compressor. Make sure that the condenser grille is clean and not clogged with dust, as this affects heat transfer.
Carefully touch the motor housing (after short-term operation or an attempt to turn on). If the motor is hot, but the refrigerator is not cold, this may indicate that compressor it is idling or there is a refrigerant leak. In normal condition, the temperature of the housing should be high, but not scalding, and the upper part of the filter-drier should be warm.
Check the condition of the starting relay, which is usually mounted on the side or bottom of the engine. If traces of melting, soot, or the smell of burnt plastic are visible on the plastic housing, then the problem most likely lies in this unit, and the engine itself may be fine. Replacing the relay is a simple procedure that often solves the starting problem.
It is also worth assessing the general condition of the wiring. Look for broken wires, signs of rodents, or oxidized contacts. Any visible damage to the insulation requires immediate repair before further diagnosis. Safety in this case is priority number one.
Necessary tools for diagnostics
To properly check the electrical part of the engine, you will need a minimum set of tools, which can be found in many home craftsmen. The main device is multimeter (tester), which allows you to measure resistance and check the integrity of the circuit. Without it, diagnostics will be only tentative.
In addition to the measuring device, prepare screwdrivers (phillips and flat-head) to remove the protective casing and dismantle the relay. You will need pliers to carefully remove the terminals and, possibly, electrical tape to mark the wires so as not to mix them up during assembly. It is also recommended to have gloves on hand to protect your hands from sharp metal edges.
- 🔧 Multimeter with continuity function and resistance measurement (Ohm)
- 🪛 Set of screwdrivers for disassembling the protective box
- 🧤 Dielectric gloves and insulating tape
- 🔦 Flashlight for illuminating darkened areas of the engine compartment
Make sure your multimeter is working properly and has charged batteries. Incorrect instrument readings can lead to erroneous conclusions and unnecessary replacement of working parts. Before starting work, switch the switch to resistance measurement mode (usually indicated by the symbol Ω) to the limit of 200 Ohm or 2 kOhm.
☑️ Preparation for diagnostics
Checking the motor windings with a multimeter
The most reliable way to determine the condition of the electrical part is winding continuity. To access the contacts, it is necessary to remove the start relay and the protective plastic casing from the compressor. On the motor body you will see three terminals, arranged in a triangle, to which the wires fit.
It is important to correctly identify the contacts: usually they are marked with letters or colors, but it is better to check the technical documentation of the specific model refrigerator. As a rule, these are a common contact, a starting winding and a working winding. The resistance between these contacts must be within certain limits.
Normal resistance values:- Operating winding: 10-30 Ohm
- Starting winding: 20-50 Ohm
- Total resistance: 30-80 Ohm
If the multimeter shows infinity (one in the most significant digit or the OL symbol), this means a winding break. In this case, the engine cannot be repaired and requires replacement. If the device shows zero or a value close to zero, this indicates a short circuit of the turns, which is also a fatal malfunction.
⚠️ Attention: When measuring resistance, make sure that you do not touch the metal probes with your hands, as this may distort the readings of the device.
What to do if the resistances differ from norms?
If the resistance values differ greatly from those indicated in the documentation (by more than 20%), this indicates an interturn short circuit. Such an engine will become very hot and consume increased current, which will lead to constant knockout of plugs or tripping of the relay protection.
Diagnostics for breakdown on the housing
One of the most dangerous malfunctions is insulation breakdown to the engine housing. In this case, voltage may appear on the metal casing of the refrigerator, which poses a real risk of electric shock to the user. You can also check for breakdown using a multimeter.
To carry out the test, set the device to the resistance measurement mode at the maximum limit (usually 2 MOhm or 20 MOhm). With one probe, touch any of the three contacts on the engine, and with the other, touch a stripped area on the compressor housing or the copper tube coming out of it. The device should show infinity.
If you see any resistance values, even very large ones, this indicates an insulation failure. Operation of such a refrigerator is strictly prohibited until the malfunction is eliminated. In domestic conditions, it is impossible to restore the insulation of the windings inside a sealed casing.
- ⚡ The device shows "1" or "OL" - the insulation is normal, there is no breakdown
- 📉 The device shows numbers - there is a current leak, operation is dangerous
- 🔌 The check must be carried out for all three contacts in turn.
It is worth noting that in rare cases, a “breakdown” can be caused by moisture inside the engine compartment. If the refrigerator stood in a damp room for a long time, condensation could settle on the contacts. In such a situation, drying with a hairdryer can help, but this does not provide guarantees.
Mechanical check: jam and performance
If the electrical part of the motor is in order (windings intact, no breakdown), but the engine does not start or is noisy, there is a high probability mechanical failure. Most often, the so-called “wedge” of the piston group occurs when the rubbing parts jam due to lack of lubrication or the ingress of foreign objects.
You can diagnose the wedge by trying to start the engine directly, bypassing the standard starting relay (this method requires caution and skill). If, when voltage is applied, a powerful beep is heard, the shaft does not rotate, and after a few seconds the thermal protection is triggered - there is a mechanical blocker.
There is a method of “wedging” by applying increased voltage, but at home it is extremely dangerous and does not guarantee results. Most often, if the compressor fails, it must be replaced. Also a sign of mechanical wear is a metallic knock, clanging or rumble during operation, which differs from the smooth hum of a working motor.
Another sign of loss of performance is when the engine runs continuously, the body is hot, but there is no cold in the chambers. This may mean that the valves inside the compressor are burnt out or worn out, and it simply drives freon without creating the necessary compression. You can check this by biting off the filling tube (only if you are planning further repairs with filter replacement and refilling).
⚠️ Attention: Opening the sealed compressor casing for mechanical repairs at home is impossible and impractical. Such engines are considered disposable components.
Frequent questions and answers (FAQ)
Is it possible to replace the compressor on a refrigerator yourself?
Theoretically, this is possible, but the process requires special equipment: a vacuum pump to remove air and moisture from the system, a pressure gauge station and scales for refilling the refrigerant. Without these tools, it will not be possible to perform a quality replacement and refill with freon, so for the final stage you will still need to call a specialist.
Why does the start relay burn out after replacement?
A frequent reason is a malfunction of the compressor itself. If the motor has high starting winding resistance or mechanical seizing, it will draw higher than normal starting current. This leads to overheating and rapid failure of the new relay. Always check the windings before installing a new relay.
How long does a refrigerator compressor last on average?
The service life of modern ones compressors is from 10 to 15 years or more, provided that the operating rules are followed. However, inverter models can operate longer due to the absence of constant starting loads. Sharp voltage surges in the network can significantly reduce this period.
Is it dangerous to touch a running compressor?
Touching a running compressor with your hands is dangerous not only because of the high temperature (you can get burned), but also because of the risk of electric shock if there are hidden insulation defects. All checks of the condition of the case should be carried out only when the device is disconnected from the network.