The situation when an LG refrigerator suddenly stops freezing, and the compressor is either silent or makes only a short click, often confuses the owner. In most cases, the cause of such a malfunction is the failure of the start-up relay, which is responsible for starting the engine and protecting its windings from overloads. Understanding where exactly this unit is located is the first step to successfully repairing household appliances without calling a technician.
The location of this element in the units of the Korean brand LG is standardized, but has its own nuances depending on the model and year of manufacture. Start relay usually hidden from the user’s eyes and requires partial disassembly of the back of the device for access. Knowing the exact installation location will save you time and allow you to quickly diagnose the problem without guessing on the coffee grounds.
In this article we will analyze in detail the design of the compressor group, indicate the exact location of the relay and describe the algorithm of actions when replacing it. You don't need to be an electronics engineer to tackle this task, but safety precautions and attention to detail are critical. Let's figure out how the starting system of your refrigerator works.
Design and role of the starting relay in the cooling system
To understand where to look for the part, you need to imagine what exactly we are looking for. The start-up relay is an electromechanical switch that supplies current to the compressor's starting winding only when it starts. As soon as the engine rotor reaches the required speed, the relay opens the starting winding circuit, and the engine continues to operate on the main winding. Models LG most often use induction-type relays or posistor variations, depending on the series of the refrigerator.
In addition to the starting function, this unit acts as a thermal fuse. Inside the housing there is a bimetallic element that opens the circuit when the temperature or current rises critically. If you hear a characteristic click, followed by a hum and the subsequent shutdown of the motor, this is a sure sign that thermal protection triggers due to the impossibility of starting the rotor. Often a stuck or burnt relay is to blame.
The device is hermetically packaged in a black plastic case, which is attached directly to the compressor terminals. Inside there are contacts, springs and a posistor (a ceramic element that changes resistance when heated). It is this compact unit that is the “heart” of the launch system. Its failure is one of the most common reasons why refrigerators stop working. LG.
⚠️ Attention: Residual currents or charges may remain inside the relay, especially if the breakdown occurred recently. Before touching the metal contacts, it is recommended to briefly short-circuit the terminals with a screwdriver with an insulated handle (after disconnecting from the network) to avoid an unpleasant electric shock.
The exact location of the relay in LG refrigerators
The answer to the question where is the relay on the refrigerator LG, is unambiguous: it is located in the lower rear part of the unit, directly on the compressor housing. To get to it you will need access to the compressor compartment. In most modern models LG the compressor is closed with a metal or plastic cover, which is secured with screws or latches.
After removing the protective panel, you will see a black cylindrical or pear-shaped tank - this is the compressor itself. The relay is placed on the side pins (winding terminals) of the motor. Depending on the layout, there may be a capacitor nearby (if the model is two-phase) and a cooling fan. The required element is always located at the lowest point of this design, since it is hung on the motor terminals.
Sometimes access to the relay is complicated by the presence of additional plastic casings or a condensate collection tray, which can be fixed above the compressor. In such cases, it is necessary to carefully dismantle the tray, after draining the water from it, if there is any. Do not pull the wires and tubes going to the compressor so as not to damage the refrigerant circulation system.
It is important to note that in some inverter models LG the starting system may differ from the classic one. However, even in them, the starting module or control unit is often located in close proximity to the motor, although it can be placed in a separate electronic unit. For classic linear compressors, the circuit remains traditional: the relay is attached to the terminals.
Symptoms of malfunction and diagnostics of the unit
Before removing the part, you need to make sure that the problem lies there. Symptoms of a faulty start-up relay are quite specific and difficult to confuse with other faults. The main symptom is cyclical operation: the refrigerator turns on, hums for 5-10 seconds, then a click is heard and it goes silent. After some time (from a minute to an hour, until the thermal protection cools down), the cycle is repeated.
Another obvious sign is a visual inspection. If you remove the relay and shake it, you may hear a knocking noise. This means that the internal contacts or the posistor have broken. Traces of soot, melted plastic, or swelling may also be visible on the body. If you observe such defects, diagnostics completed - the part requires replacement.
- 🔊 Characteristic click: A loud sound of switching on, followed by a buzzing sound and a sharp shutdown after a few seconds.
- 🔥 Case heating: The compressor or the relay itself becomes excessively hot to the touch after several attempts to start.
- 💡 Lack of cold: In the fridge compartment, the temperature rises, food begins to deteriorate, although the light inside is on.
- 👃 Scorching smell: The appearance of a specific smell of burning plastic or electrical insulation in the compressor area.
Sometimes the relay can “stick” in the closed state, which leads to a constant humming of the compressor without reaching the operating mode. In this case, the engine wears out, which can lead to an interturn short circuit. Therefore, when the first signs of unstable operation appear, it is necessary to check with a multimeter.
Instructions for dismantling and replacing the relay
The replacement process requires a minimum set of tools: a screwdriver (Phillips and flat-head), pliers and, preferably, a multimeter. The main rule is safety. Before starting any work, the refrigerator must be disconnected from the power supply. Not just turned off with a button, but removed from the socket.
First, remove the rear cover of the compressor compartment. It can be attached with 4-6 screws around the perimeter. After removing the cover, allow the compressor to cool if it was hot. Next, carefully disconnect the wires going to the relay. They can be fixed with terminals or simply inserted into sockets. It is recommended to photograph the connection diagram before disconnecting, so as not to mix up the contacts during assembly.
The relay itself is removed by gently rocking and pulling down. It sits tightly on the three pins of the compressor. If there is a capacitor, it is also attached nearby and has two wires that need to be disconnected. The new relay must fully match the markings of the old one. Install the new part on the terminals, connect the wires according to the diagram and secure the case if it has fixing brackets.
☑️ Algorithm for replacing the relay
After assembly, do not rush to close the cover completely. Plug in the refrigerator and listen. Startup should be smooth, without loud clicks or buzzing. The compressor should pick up speed and run smoothly. If everything went well, you can screw the back panel. The whole process takes from 15 to 30 minutes even for an inexperienced user.
Compatibility and markings table
When searching for spare parts LG it is important to pay attention not only to the brand, but also to the technical characteristics. Relays are selected according to compressor power and refrigerant type. Below is a table with common markings that are found in LG refrigerators.
| Relay marking | Compressor type | Power (HP) | Features |
|---|---|---|---|
| PTC R6 | Piston | 1/8 - 1/6 | Standard for low-power models |
| PTC R4 | Piston | 1/5 - 1/4 | Often found in two-chamber |
| Relay 12090304 | Linear | Inverter | Specific for LG Linear |
| PTC 128 | Piston | 1/3 | For powerful Side-by-Side refrigerators |
It is important to understand that the marking PTC indicates the presence of a posistor. The numbers after the letters indicate the initial resistance value. Replacing a relay with one resistance with a relay with another may result in the engine not starting correctly. Always check the part numbers indicated on the housing of the old relay.
Can a universal relay be used?
Universal relays (for example, the PTCR series) are suitable for many models, but their installation requires care. Often the kit includes several pairs of adapters for different compressor connectors. The main thing is to choose the right resistance for the power of your motor.
Common mistakes during self-repair
DIY Repair is always a risk, especially if you are doing it for the first time. One of the most common mistakes is ignoring the condition of the capacitor. If the starting capacitor is dry or swollen, replacing the relay will not work, and the new part may quickly fail. Always check the capacitance of the capacitor with a multimeter.
Another mistake is incorrect installation of the relay. If you mix up the contacts or do not seat the relay fully onto the pins, the contacts may spark. This will lead to burning of the compressor leads, the repair of which will cost much more than replacing the relay. It is also dangerous to use a relay that is not designed to work with this type of refrigerant (for example, R600a requires special intrinsic safety).
- ❌ Ignoring cleanliness: Dust and dirt in the compressor compartment can cause a short circuit or overheating.
- ❌ Wire tension: Wires should not touch the hot compressor tubes or moving parts of the fan.
- ❌ Lack of fixation: If the relay is not secured, vibration during compressor operation can lead to its fall and destruction.
⚠️ Attention: If After replacing the relay, the refrigerator started working, but after a few hours it stopped freezing again, perhaps the problem is deeper. This could be a freon leak or a malfunction of the compressor itself. In such cases, further operation can finish off the motor.
Prevention and extension of service life
In order for the relay and compressor to last longer, it is necessary to ensure good operating conditions. The refrigerator LG must stand on a flat surface so that vibration is minimal. The gap between the back of the unit and the wall must be at least 10 cm for normal air circulation. Overheating is the main enemy of electronics and mechanics.
Regular cleaning of the compressor compartment from dust and pet hair is also important. A dust “carpet” on the radiator grille or the compressor itself impairs heat transfer, causing the thermal protection to operate more often. Wipe the back panel with a damp cloth once every six months, after turning off the device.
Monitor the room temperature. If the refrigerator is in an unheated room where the temperature drops below +10°C, the oil in the compressor thickens and the load on the start relay increases many times over. Under such conditions, the service life of the part is reduced significantly. Following these simple rules will allow your refrigerator to operate without failures for many years.
Is it possible to repair a burnt-out relay rather than changing it?
Theoretically, you can replace the posistor inside the case by choosing a similar one in resistance. However, the relay housing is often soldered or glued, and opening it violates the tightness and fire safety. Considering the low cost of a new part, repairing an old relay is not economically feasible and can be dangerous.
Why does a new relay burn out immediately after installation?
This indicates that the cause of the breakdown was not in the relay itself. Most likely, the compressor is faulty (interturn short circuit, jammed piston group) or there are problems with the wiring and voltage in the network. It is also possible that a relay with the wrong posistor resistance was selected.
How to distinguish an original LG relay from a Chinese analogue?
Original parts LG have clear markings, a brand logo and neat assembly without burrs on the plastic. Chinese analogues are often lighter in weight, the plastic may have an odor, and the markings may be unclear. However, many trusted Chinese brands (for example, Danfoss) produce high-quality compatible parts.
Does the type of refrigerant affect the choice of relay?
Yes, it does indirectly. Compressors for different refrigerants (R134a, R600a) have different designs and capacities. The relay is selected specifically for the compressor parameters (power, starting current), and these, in turn, depend on the type of refrigerant and chamber volume. Therefore, always look at the compressor model.