If you notice that in the freezer compartment of your refrigerator LG a “coat” of ice has begun to accumulate, and food has stopped freezing to the desired temperature, this alarm signal. Often the cause of such problems is the failure of the defroster, which controls the defrosting process of the evaporator. Without the correct operation of this element, the “No Frost” system stops functioning, turning the chamber into a solid piece of ice. defrost sensor (defroster), which controls the defrosting process of the evaporator. Without the correct operation of this element, the “No Frost” system ceases to function, turning the camera into a solid piece of ice.
Diagnostics of this part does not require deep engineering knowledge, but requires compliance with safety regulations and the availability of a basic set of tools. In this article, we will look in detail at how to understand that the problem is in the sensor, what tools you will need and how to measure resistance to avoid wasting money on unnecessary spare parts.
Before you start disassembling the unit, make sure that the refrigerator is disconnected from the power supply. Handling live electrical components is strictly prohibited and may result in serious injury or damage to the control board. Next, we will look at a step-by-step algorithm of actions.
Main symptoms of a malfunction of the defroster sensor
Understanding the symptoms is half the success in repair. The defrost sensor is a temperature-sensitive element that informs the control unit about the temperature of the evaporator. If he “lies” or is silent, the refrigerator starts working in emergency mode. The first and most obvious sign is the formation of a thick layer of ice on the back wall of the freezer, even if you defrost regularly.
Attention! Sometimes ice can block the ventilation ducts, causing cold air to stop flowing into the refrigerator compartment. In this case, the products in the main chamber may begin to deteriorate, although the compressor will work continuously.
The second sign is the appearance of specific error codes on the display (if any) or blinking indicators. Models LG often have codes indicating errors in the defrosting system. It is also worth paying attention to the operation of the compressor: if it hums non-stop, trying to catch up with the temperature, but there is no cold, this may indicate that the evaporator is “clogged” with ice due to the lack of defrost cycles.
- ❄️ An ice crust builds up on the back wall of the freezer, which is difficult to remove mechanically.
- 🌡️ The temperature in the refrigerator compartment is higher than normal, despite the maximum settings.
- 🔊 The compressor works without interruptions or with very short pauses.
- 💡 The indicators on the control panel flash or show an error code (for example, Er FF).
It is important not to confuse a sensor malfunction with a breakdown Defrost heating element or a timer. If the heating element is burned out, there will also be ice, but diagnostics will require checking the heater circuit separately. The sensor acts as a “watchman” who must turn the heating on and off in time.
Necessary tools and preparation for diagnostics
For a high-quality check, you will need a minimum set of tools that most home craftsmen can find. The main device will be multimeter (tester), capable of measuring resistance (Ohms) and ringing the circuit. Without this device, diagnostics will be only speculative.
Also prepare screwdrivers (usually Phillips and flathead), a knife to carefully remove the ice (if the chamber is frozen) and a hairdryer. A hairdryer may be necessary if you decide to speed up the defrosting of the evaporator before removing the sensor, although experts recommend allowing the ice to melt naturally to avoid damaging the plastic parts.
⚠️ Attention: Never use sharp metal objects (knives, chisels) to chip the ice inside the chamber. You may accidentally pierce the evaporator tubes, which will lead to a freon leak and costly repairs at a service center.
Before starting work, be sure to defrost the refrigerator. Even if you want to check the sensor “live”, the presence of ice will make it difficult to access the back wall and the element itself. The optimal time for complete defrosting is 12 to 24 hours. This will also allow water to drain and avoid flooding electronic components during disassembly.
After defrosting, remove all shelves and drawers from the freezer. You need easy access to the back panel. In some models LG you may need to remove the bottom grille or dismantle the door for convenience, but most often it is enough to just go down to the floor level.
Removing the back panel and searching for the sensor
The defrost sensor in refrigerators LG usually located on the evaporator, hidden behind the back wall of the freezer cameras. To get to it, you need to remove the plastic panel. It can be secured with latches or screws. Carefully inspect the perimeter of the panel: sometimes the mounting bolts are hidden under decorative plugs or plastic caps.
Carefully unscrew all visible screws and pull the panel towards you. If it does not give in, do not use force - you may have missed a fastener. Inside you will see an aluminum evaporator core covered with thin tubes. The defrost sensor is a small metal cylinder (copper or brass), which is inserted into a special hole in the evaporator fins or pressed tightly against them.
Two wires come from the sensor, which are connected to the general wiring of the refrigerator. Often they are connected via a connector. Your task is to carefully disconnect this connector. Do not pull the wires, hold on to the plastic connector itself. If the connector is “stuck” from moisture, you can slightly warm it up with a hairdryer, but very carefully.
- 🔧 Unscrew the screws securing the rear panel of the freezer.
- ❄️ Carefully remove the panel, trying not to damage the fragile plastic in the cold.
- 🔍 Find the sensor: this is a “bullet” on the wires inserted into the evaporator.
- 🔌 Disconnect the sensor chip from the main wiring of the refrigerator.
Sometimes the sensor can be filled with ice. In this case, it must be carefully released. The response temperature of a standard LG defrost sensor is approximately +10...+15°C to turn on and +5...+10°C to turn offso it must be installed in the area where the ice melts first. If it is frozen into a block of ice far from the heating element, perhaps the previous technician installed it incorrectly.
Checking the sensor with a multimeter: step-by-step instructions
The most reliable way to check the serviceability of a part is to measure its electrical resistance. The defrost sensor is a thermistor, and its resistance directly depends on temperature. To carry out the test, switch the multimeter to resistance measurement mode (Ohm, limit 20 kOhm or 200 kOhm).
At room temperature (if the sensor has warmed up), the resistance should be in a certain range, usually from 4 to 10 kOhm (the exact value depends on the model, but a break or short circuit is visible immediately). If the multimeter shows “1” (infinity) or “0” (short circuit) at room temperature, the sensor is faulty.
However, a more accurate test is carried out at low temperatures. Since the sensor must respond to cold, it needs to be cooled. Place the sensor in the freezer (separate, working) for 15-20 minutes or use a quick freeze spray. After cooling, the resistance should change. If there are no changes or the readings are chaotic, the part requires replacement.
☑️ Checking the sensor with a multimeter
Compare the data obtained with the reference values. Below is a table of approximate resistance values for typical thermistors used in refrigeration.
| Temperature (°C) | Resistance (kOhm) | Status | Action |
|---|---|---|---|
| +25 (Room) | ~5 - 10 kOhm | Normal | Leave |
| -15 (Freezer) | ~20 - 40 kOhm | Normal | Leave |
| Any | 0 (Zero) | Short circuit | Replace |
| Any | ∞ (Unit) | Open circuit | Replace |
If you find that the resistance “floats” or does not correspond to the temperature, this is a sure sign of degradation of the temperature-sensitive element. In this case, the control system receives incorrect data and does not start defrosting on time.
Analysis of error codes and operation of the control board
Modern refrigerators LG are equipped with self-diagnosis. If the defrost sensor is faulty, the control board often detects this and issues an error. Symbols may light up on the display Er FF, Er dh or the temperature indicators may flash. The code Er FF most often indicates a fan motor error, but can also occur if there are problems with the defrost system if ice has blocked the blades.
A sensor-specific error code may indicate an open circuit or short circuit. The board “sees” that the sensor resistance has gone out of range (for example, it has become too high or low for the current temperature). In this case, the refrigerator may go into emergency mode, periodically turning the compressor on and off.
⚠️ Attention: Resetting the error by disconnecting the refrigerator from the network for 10-15 minutes helps only temporarily. If the physical cause (faulty sensor) is not eliminated, the error will appear again after the first cycle of operation.
It is also worth checking the condition of the wires coming from the sensor. Often a fracture occurs not in the sensor itself, but at the point where the wire enters the housing or in the area of the connector. Visually inspect the insulation for cracks and melting. “Ring” the wires from the connector to the sensor itself to prevent a break in the cable.
If the multimeter shows that the sensor is working, but the error remains, the problem may be in the control board itself or in oxidized contacts of the connector. In this case, it is recommended to treat the contacts with a spray to clean the electronics.
What to do if the error codes do not correspond to the manual?
Sometimes manufacturers change the labeling of errors in new firmware. If your code does not match the instructions, try to find the Service Manual specifically for your model using the full code (located on the nameplate inside the camera). There will be an exact decoding for a specific series.
Replacing the defrost sensor: algorithm of actions
If the diagnostics confirmed a malfunction, the sensor must be replaced. Repair of this part is impossible - the thermistor is a non-separable element. When purchasing a new spare part, be sure to check the article number or appearance with the original. Universal sensors may have a different temperature characteristic, which will lead to incorrect operation.
Install the new sensor in the same hole from which the old one was removed. It must fit tightly, without gaps, in order to accurately read the temperature of the evaporator. If the kit includes thermal paste, apply a small amount to the tip of the sensor before installation - this will improve heat transfer.
Connect the connector. Make sure that the wires are not pinched or touching moving parts or hot surfaces (although the evaporator area does not get hot, except during defrost). Reassemble the back panel in the reverse order, tighten all the screws.
- 🛒 Buy an original defrost sensor for your model LG.
- 🔩 Insert the new element into the evaporator socket until it stops.
- 🔌 Connect the connector and check the reliability of the contact.
- 🔙 Assemble the panel and turn on the refrigerator.
After turning on, the refrigerator may not immediately begin defrosting. It needs time to gain temperature and enter the operating cycle. Typically, the first defrost cycle occurs after 6-12 hours of operation. At this time, make sure that there is no ice buildup.
Prevention and frequently asked questions
To extend the life of the defrost system, monitor the condition of the door seals. If the rubber does not fit tightly, moist air enters the chamber, which quickly turns into ice. This causes the sensor and heating element to work with overload, reducing their service life.
Also, do not put hot foods in the freezer and try to minimize the time the door is opened. Excess moisture is the main enemy of the system No Frost. Regularly, at least once a year, completely defrost the refrigerator, even if it does not require this according to the instructions, in order to remove hidden ice plugs in the drainage.
⚠️ Attention: The characteristics and location of parts may vary slightly depending on the year of manufacture and the specific model of the refrigerator. Always check the manufacturer's technical documentation for your device.
Following these simple rules and timely response to symptoms of a malfunction will allow your refrigerator LG to serve for many years. Remember that a quality repair is not only replacing a part, but also understanding the reason why it failed.
Frequently asked questions (FAQ)
Is it possible to temporarily remove the jumper instead of the sensor?
Theoretically, if you close the circuit, the refrigerator will think that the temperature always allows defrost, or vice versa, depending on the logic of the board. However, this strongly not recommended. Without a sensor, the heating element may turn on at the wrong time (for example, when the chamber is warm) or not turn off, which will lead to food spoilage or even a fire. The sensor is a safety element.
Why does the error not disappear after replacing the sensor?
In some models LG you need to manually reset the error. Try unplugging the refrigerator for 20-30 minutes. If this does not help, perhaps the problem is not in the sensor, but in the defrost heating element itself or in the control board. Also check whether the new sensor is firmly inserted into its socket.
What is the service life of a defrost sensor?
The average service life of a thermistor is 5-7 years, but it greatly depends on operating conditions. Frequent power surges, high humidity and constant defrosting cycles can shorten this period. If your refrigerator is more than 10 years old, replacing the sensor is a planned procedure.
Can you use a sensor from another refrigerator model?
Only if their temperature characteristics (resistance curve) match. Visual similarity does not guarantee identical parameters. Using the wrong sensor will lead to incorrect defrost cycles: either the ice will not have time to melt, or the heating element will heat in vain, consuming electricity.