How to ring the compressor of an LG refrigerator: complete instructions

A sudden breakdown of refrigeration equipment always becomes an unpleasant surprise, especially if there are perishable products in the chamber. Often equipment owners LG face a situation where the unit stops cooling, but continues to hum or, conversely, remains silent. The first step in troubleshooting is diagnosing the motor, which is the heart of the entire cooling system. Understanding how to ring the compressor of an LG refrigerator will allow you to save time and money on calling a technician if the problem turns out to be in the electrical part.

Modern refrigerators of the South Korean brand are equipped with reliable engines, but they are also subject to wear, power surges and overheating. Before you pick up measuring instruments, you must clearly understand that you will be working with high voltage and a complex mechanical assembly. Safety in this process comes first, so ignoring electrical safety rules is unacceptable. In this article, we will analyze in detail the algorithm of actions, the necessary tools and decoding of the multimeter readings.

If you have never encountered the repair of household appliances before, do not rush to disassemble the unit. First, make sure that the problem really lies with the motor and not with the thermostat or control board. Compressor diagnostics is a process of eliminating other factors that requires care and precision. A correct check of the windings will give an unambiguous answer: whether your refrigerator can be restored or the unit needs to be replaced.

Preparation for diagnostics and safety measures

Before you begin directly checking the electrical circuits, you need to prepare your workplace and tools. You will need access to the back of the refrigerator where the motor-compressor is located. Make sure the area is well lit and the floor is dry to reduce the risk of electric shock or falls. The main diagnostic tool will be multimeter, which must be in working order and have a charged battery.

The most critical stage of preparation is to completely de-energize the device. It is not enough to simply turn off the refrigerator with a button or temperature regulator - you must physically remove the plug from the socket. Any manipulation with live electrical contacts is deadly. After disconnecting from the network, let the equipment stand for 10-15 minutes so that the residual charge in the capacitors (if they are in the control circuit) dissipates and the refrigerant stabilizes.

⚠️ Attention: Never start disassembling and testing contacts if the power cord is connected to the network, even if the refrigerator is turned off by the regulator. The phase may be present on the relay contacts and windings, which will lead to an electric shock.

For work you will need the following tools and materials:

• 🔧 Multimeter (digital or analog) for measuring resistance.
• 🪛 A set of screwdrivers (phillips and flat) for removing the protective casing.
• 🧤 Dielectric gloves for additional hand protection.
• 🔦 Flashlight for illuminating hard-to-reach places in the compressor niche.
• 🧹 Dry rags for cleaning contacts from dust and oxides.

After removal protective plastic or metal casing covering the compressor, carefully visually inspect the condition of the wires and connectors. Look for signs of melting, black deposits or obvious breaks. If oil smudges are visible on the motor housing, this may indicate mechanical depressurization, and in this case, electrical testing may no longer be relevant - the unit requires replacement.

Access to the electrical contacts of the compressor

To ring the windings, you need to gain access to the contact group. On the back wall of the refrigerator LG the compressor is usually closed with a round metal casing, which is secured with latches or screws. Carefully remove the clips, being careful not to damage them, as the plastic becomes brittle over time. Under the casing you will see the motor itself, to the bottom of which a start-protective relay-regulator is attached.

The next step is to remove the start relay. This is a plastic box placed over the compressor contacts. It can be mounted on latches or a metal bracket. Carefully bend the clips and remove the relay down, disconnecting it from the contact group. It is through these contacts that voltage is supplied to the motor windings. It is important not to confuse the position of the relay when removing it, so that later you can correctly install it back for checking. stator engine. It is important not to confuse the position of the relay when removing it, so that later you can correctly install it back for testing.

On the contact group of the compressor there are usually three pins forming a triangle. They may be lettered or color coded, but often the markings are worn off or missing. The standard marking looks like this:

• ⚡ C (Common) - common contact.
• ⚡ R (Run) - working winding.
• ⚡ S (Start) - starting winding.

Sometimes, instead of Latin letters, numbers or color coding of wires coming from relay In refrigerators LG there is often a circuit where the common wire is black, the working wire is red or white, and the starting wire is blue or green. However, you cannot rely only on the color of the wires, since previous masters may have made changes. The most reliable way is to test the resistance with a multimeter.

⚠️ Attention: When removing the start relay, proceed carefully. The plastic housing contains fragile components and the contacts may oxidize. A sharp tug can lead to breakage of the relay latches, which will make it impossible to reinstall it.

Algorithm for checking windings with a multimeter

The process of measuring winding resistance requires switching the multimeter to the resistance measurement mode (Ohm), usually indicated by the symbol Ω. Select a measurement limit of 200 ohms or 2 kohms. First, it is necessary to clean the contacts on the compressor terminals if they are oxidized to ensure reliable contact of the probes. Touch the multimeter probes to the pairs of contacts and write down the resulting values.

You need to take three basic measurements between pairs of contacts:

1. Measurement between pin 1 and pin 2.
2. Measurement between pin 2 and pin 3.
3. Measurement between pin 1 and pin 3.

Based on the data obtained, you need to determine which pin is common. The logic is simple: the greatest resistance will be between the starting and working windings (the sum of the resistances). The smallest resistance is the working winding, and the average is the starting winding. The common wire will participate in two measurements, giving the smallest amounts when paired with others.

Calculation example:
Measurement 1-2: 30 Ohm
Measurement 2-3: 15 Ohm
Measurement 1-3: 45 Ohm
Conclusion: The largest 45 Ohms (1-3) is the sum.
Pin 2 is involved in measurements with the lowest values (30 and 15), which means this is the Common wire (C).
Between C and 3 (15 Ohms) - Working winding (R).
Between C and 1 (30 Ohm) - Start winding (S).

Normal resistance values for compressors LG vary depending on the motor power, but usually fall within the following ranges:

• 📉 Working winding: from 10 to 35 Ohms.
• 📈 Starting winding: from 20 to 60 Ohms (always higher than the working one).
• 🔗 Total resistance: the sum of the two above.

Diagnostics of breakdown to the case and interturn short circuit

In addition to checking the integrity of the windings, it is critically important to ensure that there is no insulation breakdown on the motor housing. If the winding touches the metal body of the compressor, this will trigger the circuit breakers in the panel or cause an electric shock when it touches the body of the refrigerator. To check, switch the multimeter to the dial mode (with a sound signal) or resistance measurement to the maximum limit (2 MOhm and higher).

Press one probe to any of the three contacts of the compressor (after cleaning the contact area from paint or oxides), and press the second probe tightly to the metal tube of the fitting or to the unpainted part of the motor housing. If the device shows a resistance close to infinity (on a digital multimeter “1” or “OL”) and is silent, the insulation is intact. The appearance of any numbers or a sound signal indicates a breakdown.

An interturn short circuit can be more difficult to diagnose. In this case, the resistance of the windings may be normal, but the engine will heat up, hum and knock out the thermal relay. Accurate determination of an interturn short circuit at home is difficult, but indirect signs are:

• 🔥 Fast and strong heating of the compressor housing during operation.
• 🔌 Triggering of a thermal protection relay at short intervals.
• 📉 Low resistance readings windings compared to reference data for a specific model.

Is it possible to revive a motor with an interturn short circuit?

At home, it is almost impossible to rewind a refrigerator compressor. Special equipment is required for evacuation, freon charging and precise balancing of the rotor. It is more economically feasible to replace the entire assembly.

It is also worth considering that the resistance characteristics may vary slightly depending on the temperature of the windings. A cold engine will show less resistance than a hot one. If you carry out diagnostics immediately after operating the refrigerator, the readings may be higher than nominal.

Checking the starting relay and thermal protector

Often the reason for a non-working compressor is not the motor itself, but the starting relay. This device supplies an impulse to the starting winding to start the rotor. In refrigerators LG posistor relays are often used. Inside them there is a ceramic element (posistor), which, when heated by current, sharply increases its resistance, breaking the starting winding circuit.

To check the relay, it must be disassembled by removing the posistor from the plastic case. Visually inspect the element: there should be no cracks, chips or burn marks on it. Test the posistor with a multimeter: at room temperature its resistance should be several tens of ohms (usually 10-50 ohms). If the device shows a break or resistance close to zero, the part is faulty.

The second element that requires checking is the thermal release (thermoprotector). It protects the motor from overheating. In a cold state, its contacts should be closed (resistance 0 Ohm, there is a sound signal). If the multimeter shows an open on the cold relay, then the circuit is open and the compressor will not start. Heating the thermal protector with a hairdryer should open the contacts, and cooling should close them again.

⚠️ Attention: Replacement of the starting relay should only be done with one of similar characteristics. Installing an unsuitable relay may result in the compressor being unable to start or the winding burning out due to the starting circuit being energized for a long time.

Table of typical faults and their symptoms:

Interpretation of results and further actions

After all measurements have been carried out, it is necessary to analyze the data obtained. If the resistance of the windings is normal, there is no breakdown to the housing, and the relay is working properly, but the refrigerator does not work, the problem may lie deeper. Perhaps the electronic control module is faulty, which does not supply voltage to the compressor, or the temperature sensor is faulty.

If measurements show a break in one of the windings or a breakdown in the housing, the compressor is considered faulty. Repairing such an engine at home is impossible and economically infeasible. The only correct solution is to replace the compressor with a new one. When replacing, it is important to follow the technology: evacuation of the system, filling the exact amount of refrigerant and replacing the filter-drier.

If you find that everything is in order with the electrical part, but the engine hums and does not start (or starts for a split second), there is a high probability of mechanical jamming. This occurs due to wear and tear of rubbing parts or lack of oil. Attempts to “unwedge” the compressor by applying increased voltage are dangerous and rarely give long-term results.

For owners of refrigerators LG with inverter compressors, diagnostics become much more complicated. Such motors do not have a classic starting winding and relay, but are controlled by a frequency converter. You can test them with a regular multimeter only to check for breakdown of the windings on the housing (the resistance between the phases and the ground should be the same and not go to zero). Checking the performance of an inverter motor without a special tester is almost impossible.

Is it worth changing the compressor yourself?

Replacing a compressor requires professional equipment: a vacuum pump, a pressure gauge station, a soldering torch and scales for charging freon. Without experience and tools, there is a high risk of damaging a new compressor or breaking the tightness of the circuit.

Frequently asked questions (FAQ)

Is it possible to check a compressor without a multimeter?

It is impossible to qualitatively check the windings without instruments. However, you can indirectly judge the condition: if, when connected to the network, the compressor hums for 5-10 seconds and clicks (thermal is triggered), and then goes silent, most likely the problem is in the start relay or mechanical jamming. If there is complete silence, there may be an open circuit or an electronic malfunction. But only a continuity test will give an accurate diagnosis.

What resistance is considered normal for an LG refrigerator?

For most refrigerator models LG the resistance of the working winding varies between 15-25 Ohms, and the starting winding - 30-50 Ohms. The main rule: the resistance of the starting winding should always be higher than the resistance of the working winding. The exact values ​​depend on the specific motor model and its power.

What to do if the multimeter shows 0 Ohm?

A reading of 0 Ohm (or close to it) between the winding contacts indicates a short interturn circuit. Such a compressor cannot be operated, as this will lead to network overload, fire or permanent engine failure. The unit needs to be replaced.

Can a compressor be electrically functional, but not work?

Yes, this is possible. Electrical serviceability (integrity of windings) does not guarantee mechanical serviceability. The piston group may be seized due to wear, contamination of the system, or lack of lubrication. In this case, the motor will hum, but will not be able to create the necessary pressure for the circulation of the refrigerant.

Is it dangerous to touch the compressor tubes during diagnostics?

When the refrigerator is unplugged, it is safe to touch the tubes. However, if you are doing a test run to check operation, be careful: the discharge tube may become very hot and the suction tube may become frosted. In addition, in the event of a freon leak and the presence of a spark, ignition is theoretically possible, so it is better to carry out work in a ventilated area.