If you are faced with the fact that in your refrigerator Samsung the No Frost system has stopped working, and a “coat” of ice is growing on the back wall of the freezer, most likely one has failed from elements of the defrost system. Most often, the culprit is the evaporator temperature sensor or thermal fuse, which simply burns out. Understanding where exactly it is located is the first and most important step to successfully repairing household appliances with your own hands.
In this article we will analyze in detail the design of the evaporator unit, explain the difference between the different types of sensors and provide a step-by-step algorithm for removing them for testing. You don't need to be a professional engineer to understand the device, but accuracy and care are required. We will look at the nuances of dismantling panels and the features of fastening heating elements in different models of the Korean brand.
Before starting disassembly, we strongly advise you to prepare the necessary tools: Phillips and flat-head screwdrivers, a multimeter for checking the circuit and, possibly, a hair dryer for defrosting ice if the chamber is already icy. Do not forget that any work with electrical appliances requires prior disconnection from the power supply to avoid electric shock. Safety is the number one priority in any repair.
Design features of the Samsung defrosting system
The automatic defrosting system in refrigerators Samsung is designed quite reliably, but has its own characteristic features that distinguish it from equipment from other manufacturers. The main unit here is the evaporator, hidden behind a plastic panel on the back wall of the freezer. It is around this element that the refrigerant circulates, cooling the space inside the chamber.
The defrost cycle is started by a timer or control board algorithm, after which the heating element (heating element) is turned on. To prevent the process from getting out of control and leading to melting of plastic parts or fire, there are protective devices in the circuit. Their location and quantity depend on the specific series of the refrigerator, be it RB30, RL34 or older models.
It is important to understand that “defrost sensor” is a general name. In fact, there may be two different elements in the circuit: the temperature sensor itself (thermistor), which tells the control unit the temperature of the evaporator, and a thermal fuse (thermal fuse), which physically breaks the circuit during critical overheating. Thermistor usually changes its resistance, and thermal fuse burns out once.
The location of these components is designed to provide the most accurate reading of the temperature of the coldest or hottest part of the system. In most modern models, they are located in close proximity to the heating tube that goes around the lower part of the evaporator. Access to them is possible only after removing the protective casing.
Where exactly to look for the sensor: location area
The search for a faulty element begins with determining its exact location inside the freezer compartment. In refrigerators Samsung with the No Frost system, the defrost sensor and thermal fuse are almost always attached to the evaporator itself. To see them, you will have to remove the back panel of the freezer.
After removing the plastic cover, you will see an aluminum evaporator radiator with copper tubes passing through it. At the bottom of this radiator, usually on the right or left side (rarely in the middle), there will be a plastic sleeve or clamp into which the sensor is inserted. Next to it you can often see a cylindrical metal element - this is a thermal fuse.
In some modifications, for example, in series with technology Twin Cooling, the design may be slightly complicated by the presence of an additional fan, but the principle remains the same. The sensor must be in contact with the surface of the evaporator or located in a special socket where air is supplied from the evaporator. The fastening is often made in the form of a clip, which must be carefully squeezed out.
Pay attention to the wires coming from these elements. They are usually assembled into a bundle and connected to a connector, which is either on the panel itself or located outside the camera. The color marking of the wires can vary, but most often it is white, red or blue insulation colors. It is important not to damage the insulation of the wires during dismantling, since in conditions of low temperatures and humidity it becomes brittle.
Instructions for dismantling the panel and accessing the sensor
The process of gaining access to the defrost sensor requires sequential actions so as not to damage the plastic latches and fasteners. First you need to completely empty the freezer of food, shelves and drawers. If there is ice on the wall, let the refrigerator stand turned off for several hours or carefully use a hair dryer to melt the ice that is preventing the panel from being removed.
Next, you should unscrew all visible screws securing the back plastic panel. In models Samsung they can be hidden under decorative plugs or located in recesses. After unscrewing the screws, the panel must be carefully pulled towards you, starting from the bottom, since the top part is often held on hooks extending behind the body.
When the panel is removed, you will see the evaporator and the components attached to it. The defrost sensor is usually inserted into a special hole in the aluminum evaporator plates and secured with a plastic clamp or clip. To remove it, you need to lightly pull the sensor body, having first disconnected it from the wiring connector.
☑️ Procedure for disassembling the freezer
When working with plastic elements, be extremely careful Be careful: in the cold the plastic becomes very brittle. Sudden movement can lead to breakage of the panel latches, which will further cause problems with tightness and loss of cold. If the panel sits tightly, do not use force, but check that all the screws are unscrewed.
Visual diagnostics and types of sensors
After you have gained access to the insides of the evaporator, you need to visually inspect the defrost sensor and thermal fuse. They may look different depending on the year and model of your Samsung. Older models were often equipped with sensors in the form of an oblong capsule, while newer ones use more compact options.
The thermal fuse is usually a small metal cylinder, similar to a resistor, with two wires. It may be enclosed in heat shrink tubing or a plastic casing. The temperature sensor (thermistor) most often has the shape of a bullet or oval and is also connected by two wires. The fuse body may be marked with an indication of the response temperature, for example, 72°C or 85°C.
Pay attention to the condition of the wires. If you see traces of melted insulation, blackening or oxidation of contacts, this is a sure sign that the system has overheated or short circuited. In such cases, simply replacing the sensor may not solve the problem if the root cause is not eliminated, for example, a malfunction of the heating element or relay.
Is it possible to restore a blown fuse?
Technically, a thermal fuse is a disposable element. Some craftsmen practice replacing it with a jumper or soldering, but this is STRICTLY prohibited from doing at home. Disabling the protection may cause the refrigerator to catch fire the next time the defrost system fails. Always install a new original fuse.
It is also worth checking if there are any signs of mechanical damage or corrosion on the sensor. Although the sensor itself is sealed, damage to the integrity of its housing will lead to moisture getting inside and a change in resistance, which will cause errors in the operation of the electronics. Any defects in the housing require mandatory replacement of the element.
Table of characteristics and element codes
To select the correct spare part, you need to know the markings. Refrigerators Samsung use various modifications of sensors and fuses. Below is a table with the most common options that can be found during repairs.
| Element type | Marking / Code | Parameters | Location |
|---|---|---|---|
| Thermal fuse | 4711-001173 (or analogues) | 72°C ±5°C, 10A 250V | On the evaporator heating element tube |
| Defrost sensor (Thermistor) | DA32-00015B / DA32-10104N | 50 kOhm at 25°C | In the aluminum evaporator sleeve |
| Defrost sensor (New type) | DA32-00033A | 10 kOhm at 25°C | On the fins of the evaporator |
| Defrost heating element | DA47-00236B | 180-220 W | At the bottom of the evaporator |
Part codes may vary depending on the region of delivery and the specific modification of the refrigerator. Always check the markings on the body of the old part with the new one before purchasing. Using a sensor that is not suitable for resistance will result in incorrect operation of the defrost cycle: either the refrigerator will defrost too often or will not do it at all.
When ordering spare parts through online stores or service centers, be sure to indicate the full model of your refrigerator, which is located on the sticker inside the chamber or on the back wall of the case. This will help the seller select a compatible analogue if the original part is discontinued.
Checking serviceability with a multimeter
Before going to the store for a new spare part, it makes sense to check the old one. To do this, you will need a multimeter switched to resistance measurement mode (Ohms). First, check the thermal fuse: it should “ring”, that is, show resistance close to zero. If the device shows one or infinity, the fuse has blown.
With a temperature sensor (thermistor), the situation is more complicated. At room temperature it should show a certain resistance (usually from 5 to 50 kOhm depending on the model). If you put the sensor in the freezer for 10-15 minutes, its resistance should change. If the resistance does not change or is zero/infinity, the sensor is faulty.
When checking, do not touch the multimeter probes with your hands, as skin resistance can distort the readings, especially at high ranges. Also make sure that the sensor wires are not broken at the very entrance to the housing - this is a frequent breakdown due to vibration and kinks.
Frequent replacement errors and precautions
One of the common mistakes is ignoring the condition of the drainage system. If the defrost sensor burned out because the water did not drain and flooded the heating element, then simply replacing the sensor will not help. It is necessary to clean the drainage hole located under the evaporator and make sure that water flows freely into the tray.
Another error is poor contact in the connection. When installing a new sensor or fuse, the wires are often twisted and insulated with electrical tape. In a refrigerator, this is unacceptable: condensation will penetrate inside the twist, oxidation will begin, and the contact will be lost. Use factory connectors or high-quality soldering followed by heat shrink.
⚠️ Attention: Never leave sensor wires simply twisted without insulation. Moisture inside the chamber will lead to a short circuit, which can damage the main control module of the refrigerator, the cost of which significantly exceeds the price of the sensor.
It is also important to install the sensor correctly in the mounting location. It should fit tightly to the surface of the evaporator. If it hangs in the air, the temperature reading will be incorrect and the defrost cycle will not start on time. Use standard clips and fasteners.
Remember that the design of refrigerators may vary slightly in different batches. If you see that the arrangement of elements differs from that described, do not use force. Study the diagram of your specific model or refer to the technical documentation.
⚠️ Attention: The configuration of internal components and markings of parts may vary depending on the year of manufacture and country of origin. Before ordering spare parts and starting disassembly, check the visual arrangement of the elements with your actual situation.
FAQ: Frequently asked questions
Is it possible to operate a refrigerator without a defrost sensor?
No, this is impossible and dangerous. The control unit will not receive a signal about the evaporator temperature and will either not turn on the defrost or turn it on forever. In the first case, the refrigerator will become clogged with ice and stop freezing, in the second, the heating element will burn out or a fire will occur