Sudden defrosting of food and silence in the kitchen instead of the usual hum, these are the first signals that make the owner think about a serious breakdown. Compressor is the heart of the refrigeration system, and its failure leads to a complete stop in the operation of the unit. In most cases, it is this unit that fails first during power surges or long-term operation without maintenance.
Before calling a technician or looking for a replacement, it is necessary to conduct an initial diagnosis in order to accurately understand the scale of the problem. Users often confuse the failure of the starting relay with a burnt-out motor, which leads to unnecessary expenses on the purchase of an expensive unit. Modern inverter models and classic linear motors have their own diagnostic features that are important to consider when checking.
In this article we will analyze in detail the algorithm of actions that allows for high accuracy determine the condition of the engine. You will learn to distinguish between the symptoms of wedge, turn-to-turn short circuit and winding break using the tools available. A competent assessment of the situation will help save time and money by making the right decision on repair or disposal of equipment.
Primary visual and auditory diagnostics
The first stage of testing is always an external inspection and analysis of the sound of the device. If the refrigerator has stopped freezing, but at the same time makes quiet clicks or a hum that ends abruptly, this may indicate an attempt to start. Start relay in such cases, it often clicks, trying to start the jammed shaft, but to no avail.
⚠️ Attention: If you If you hear a loud bang or smell burning wiring, immediately unplug the refrigerator. Further attempts to turn on may lead to a short circuit in the electrical wiring of the apartment.
Pay attention to the temperature of the compressor housing. When the engine is running, it heats up, but if it is hot to the point where it is impossible to touch it, and there is no cold, this is a sign of overheating due to jamming or problems with thermoregulation. At the same time, an absolutely cold motor when the refrigerator is plugged in indicates a lack of voltage supply or an open circuit.
Visually inspect the back of the unit for swelling, blackening or traces of soot in the area of the motor. Often when turn-to-turn short circuit an insulation breakdown occurs, leaving characteristic marks on the housing or nearby components. Also check the integrity of the wires going to the terminal box.
Analysis of the operation of the starting relay and electrical circuit
Before sinning on the motor itself, it is necessary to exclude a malfunction of the start-protective relay. This small element is responsible for providing a starting impulse and overload protection. If the relay is faulty, it may not send a signal to start, creating the illusion of a burnt-out compressor, while the engine itself is completely fine.
To check the relay, it must be removed and gently shaken. If a ringing or knocking sound is heard inside, it means that the core or contacts have broken, and the element requires replacement. In LG or Samsung inverter refrigerators the relay can be integrated into the control board, which complicates diagnostics without special equipment.
- 🔌 Unplug the refrigerator and remove the protective cover from the back.
- 🔧 Carefully disconnect the wires from the start relay and remove it from the compressor contacts.
- 👀 Inspect the contacts for soot, oxidation or melting of the plastic.
- 🔊 Shake the relay: the presence of a knock indicates internal destruction of the mechanism.
It is also important to check the integrity supply wires. Oxidized contacts at the junction of the relay and the compressor can create high contact resistance, preventing normal starting. Cleaning the contacts and installing a new relay often solves the “no start” problem without requiring replacement of an expensive motor.
Checking the compressor with a multimeter: step-by-step instructions
The most accurate way to determine the condition The motor windings are tested using a multimeter. This method allows you to detect open circuits or short circuits that are not visible during external inspection. To carry out the procedure, you will need to switch the device to resistance measurement mode (Ohm).
Remove the terminal box cover on the compressor and disconnect all wires. You have access to three contacts: two working (main and starting windings) and one common. In single-phase motors the resistance between the contacts must fit within certain standards, deviation from which indicates a malfunction.
- Connect the multimeter probes to the common contact and the contact of the main winding.
- Record the resistance readings, they should be the smallest.
- Switch the probes to the common contact and the starting winding - the resistance will be higher.
- Measure the resistance between the main and starting winding - it should be the sum of the two previous values.
If the device shows one (infinity) in any of the sections, it means in the winding occurred break. If the resistance is close to zero or significantly lower than normal, this indicates an interturn short circuit. In both cases, the compressor is considered faulty and requires replacement, since rewinding at home is impossible.
☑️ Diagnostics with a multimeter
Table of symptoms of compressor malfunctions
To systematize the received data and To simplify diagnostics, we recommend using a summary table. It helps to compare symptoms, instrument readings and the probable cause of the breakdown. This is especially useful when the signs of a malfunction are vague.
| Symptom | Multimeter readings | Sound at startup | Probable cause |
|---|---|---|---|
| The refrigerator does not freezes | Resistance is infinity | Silence | Break winding |
| Knocks out the machine | Resistance is close to 0 | Buzzing and clicking | Interturn short circuit |
| Warm case, no cold | Resistance is normal | Buzzing, then clicking | Wedge of the mechanical part |
| Works in jerks | Resistance floats | Unstable hum | Breakage to the body |
Please note that the readings Resistance may vary depending on engine power and model. For example, Danfoss compressors norms may differ from indicators Atlant or Zanussi. Always check the technical documentation of the specific model, if possible.
If the multimeter shows normal resistance, but the engine does not start or knocks out the protection, there is a high probability of mechanical jamming of the piston group. In this case, the electrical part is intact, but the physical movement of the parts is blocked, which requires professional intervention or replacement of the unit.
Checking for insulation breakdown and short circuit to the body
One of the most dangerous malfunctions is breakdown of winding insulation on the compressor housing. This may result in electric shock if you touch metal parts of the refrigerator. To check this parameter, the multimeter is switched to resistance measurement mode at the maximum limit or continuity mode.
One probe is pressed against any of the three contacts of the terminal block, and the second is pressed to a place on the motor body that has been cleared of paint (for example, to a copper tube or metal casing). With proper insulation, the device should show infinity (one in the most significant digit). Any other readings indicate a breakdown.
⚠️ Attention: Operating a refrigerator with a breakdown of insulation on the body is strictly prohibited. This poses a direct threat to the lives of people and pets. Immediate shutdown and replacement of the compressor is required.
Often a breakdown occurs due to aging of the insulation, overheating or moisture entering the casing. In some cases, if the breakdown is insignificant, the refrigerator may work, but when you touch it with your hand, a slight tingling sensation is felt. Ignoring this sign is unacceptable, since the situation can sharply worsen.
Can an insulation breakdown be eliminated?
Theoretically, the location of the breakdown can be found and insulated by disassembling the compressor housing, but this requires evacuation and charging with freon at the factory. In everyday life, such a procedure is impossible and economically inexpedient, therefore, in the event of a breakdown, the compressor must only be replaced.
Mechanical wear and jamming of the piston group
The situation when the electrical parameters are normal, but the engine does not start, often indicates a mechanical problem. Inside the sealed casing is a complex mechanism with pistons and valves, which wears out over time. Lack of lubrication or the entry of wear products into the rubbing pairs leads to jamming.
When you try to start a jammed compressor, a characteristic sound is heard: the motor hums, trying to turn, but the shaft stands still. After a few seconds, the thermal protection or start relay is activated, breaking the circuit, and the process repeats cyclically. This phenomenon is called “working on a jammed rotor.”
- 🛑 The compressor gets very hot in the lower part.
- 🔊 A monotonous hum is heard, turning into a shutdown click.
- 📉 The cold in the chambers does not accumulate, freon does not circulates.
- ⚡ Electricity consumption may be higher than normal during startup attempts.
There is a “wedging” method by applying increased voltage, but it is extremely risky and can lead to final burnout of the windings or depressurization of the casing. In a home workshop, it is safer and more reliable to decide to replace the unit than to try to revive a mechanically damaged unit.
Specifics of diagnosing inverter compressors
Modern refrigerators are increasingly equipped inverter compressorswhich are fundamentally different from classic linear models. They do not have a start relay in the usual sense and are controlled by a special electronic unit. Testing the windings with a multimeter here gives different results and requires knowledge of the circuit of a particular motor.
In inverter motors, the windings are often connected in a star or delta pattern inside, and the resistance between the contacts can be the same. In addition, such systems often have built-in temperature and rotor position sensors, which also affect startup. A malfunction of the motor itself is less common than a breakdown of the control board (inverter).
Diagnostics of inverter systems often requires connecting a special tester or replacing the control unit with a known good one. Self-diagnosis without the appropriate experience and equipment is difficult here, since an error in determining the malfunction can lead to the purchase of an unnecessary expensive compressor when the problem was in the electronics.
⚠️ Attention: The design and connection diagram of inverter compressors may differ from one manufacturer to another. Before diagnosing, be sure to find the service documentation (Service Manual) for your specific refrigerator model.
If you are the owner of Samsung refrigerator with digital inverter or LG Linear, keep in mind that these systems are very sensitive to power surges. Often the cause of failure is not the motor itself, but a burnt-out control module due to an unstable network. Installing a voltage stabilizer can prevent the situation from recurring.
Frequently asked questions (FAQ)
Is it possible to repair a burnt out compressor or just replace it?
B In 99% of cases, a burnt out compressor must only be replaced. Opening the sealed casing, rewinding the windings and subsequent vacuum sealing requires factory equipment and costs more than the price of a new unit. Only external elements are considered repairable: relays, capacitors and wires.
How long does a compressor last in a refrigerator on average?
The average service life of a modern compressor is from 10 to 15 years, provided there is a stable voltage in the network and proper operation. Inverter models theoretically, they last longer due to the lack of constant start-stop cycles that reduce mechanical wear.
Why does a new compressor burn out immediately after installation?
This can happen for several reasons: the presence of moisture or acid in the system (if the circuit has not been completely flushed), a malfunction of the start relay, lack of proper evacuation or problems with the thermostat, causing the motor to work without interruption.
Is it dangerous to change the compressor yourself?
Yes, it is dangerous and difficult. The process requires working with flammable or under pressure gases (freon), using a vacuum pump, a torch and special tools for soldering copper tubes. Without skills and equipment, there is a high risk of an explosion, fire or poor-quality repair that will quickly fail.
How to extend the life of a compressor?
It is necessary to keep the condenser at the back of the refrigerator clean (dust worsens heat transfer), do not place the refrigerator close to the wall, avoid frequent defrosting with a knife and use a voltage stabilizer if there are races.