Belarusian brand refrigerators Atlant are deservedly popular due to their reliability and maintainability. However, even the highest quality equipment requires attention over time, especially when it comes to the No Frost system. Owners often encounter a situation where the unit stops freezing, but the compressor runs continuously. One of the most common causes of such a breakdown is the failure or displacement of the evaporator defrost sensor.
Understanding where exactly this element is located is the first step towards self-diagnosis. The location of the sensor directly affects how the controller manages defrost cycles. If you notice ice on the back wall or in the freezer, and also hear a constant hum from the motor, then the problem probably lies in the evaporator temperature sensor circuit. In this article, we will analyze in detail the design of the unit, how to find it and testing methods.
Before you begin disassembly, you need to prepare the tool and free up space. You will need a Phillips screwdriver, a multimeter to check the continuity of the circuit, and possibly a hair dryer to speed up the defrosting of the ice. It is critically important to completely de-energize the refrigerator before starting work by unplugging the power cord from the outlet. Ignoring this safety rule may result in electric shock or damage to the electronics.
The principle of operation of the defrost system in Atlant refrigerators
No Frost system in refrigerators Atlant is built on forced air circulation and periodic automatic defrosting of the evaporator. The heart of this process is control unit, which receives signals from various sensors. The key element here is the evaporator temperature sensor (thermocouple), which monitors the degree of freezing of the radiator.
When the temperature on the evaporator drops to a certain value (usually about -10°C...-15°C), the sensor sends a signal to turn on the heating element. The heating element melts the ice, turning it into water, which flows into the drain pan. As soon as the ice completely melts and the temperature rises to +5°C...+10°C, the sensor opens the circuit and heating stops. If this cycle is disrupted, the refrigerator begins to work incorrectly.
In models with two compressors or a system Frost Control algorithms may differ, but the physical location of the sensor remains similar. It is always in contact with the surface of the evaporator or is in close proximity to its fins. Loss of contact or breakdown of the element itself leads to the fact that the “brain” of the refrigerator does not understand that it is time to start defrosting, or, conversely, does not see that it has already been completed.
It is worth noting that some modern models use not just a bimetallic sensor, but more complex thermistors with a nonlinear resistance characteristic. Their verification requires more accurate instruments. However, visually and physically they are located in the same area as classic thermocouples.
Where is the evaporator sensor: search in the freezer
In most refrigerators Atlant with the No Frost system, the main evaporator is hidden behind the back wall of the freezer. This is where you need to look for the sensor. To get to it, you will have to remove the inner plastic panel. This is a standard procedure for servicing the defrost unit.
After removing the panel, you will see an aluminum evaporator radiator - this is a corrugated metal surface along which the refrigerant circulates. Temperature sensor usually attached to one of the tubes of this radiator or inserted into a special hole between the fins. In Atlant models, it often takes the form of a small cylindrical element pressed to the metal by a spring or a plastic clip.
The wire from the sensor goes to the control unit, which in different models can be located on top of the refrigerator (behind the decorative panel) or in a niche above the freezer. It is important not to confuse the evaporator sensor with the air sensor in the chamber, which usually hangs freely and is not attached to anything.
⚠️ Attention: When removing the back panel of the freezer, proceed with extreme caution. Plastic becomes brittle in the cold, and sudden movement can lead to breakage of fasteners. It is recommended to preheat the joints with a hairdryer at a low temperature.
Often the sensor is “embedded” in an ice coat. If you see that the element is completely covered with ice, do not try to pick it out with a knife or screwdriver. You risk damaging the thin evaporator tube, which will lead to freon leakage and costly repairs. Let the ice melt naturally or use the warm air of a hair dryer.
Instructions for dismantling and accessing the sensor
The process of accessing the sensor requires a sequence of actions. First you need to completely defrost the refrigerator. Even if it seems to you that there is not much ice, its presence interferes with correct diagnosis. After defrosting, you can begin disassembling.
First of all, the shelves and drawers of the freezer are removed. Then the screws holding the rear plastic panel are unscrewed. In some models Atlant the panel is held on by latches that need to be carefully released with a flat-head screwdriver. After removing the panel, access to the evaporator opens.
☑️ Algorithm for accessing the sensor
Find the wires going to the evaporator. Usually there are two of them: one goes to the defrost heating element, the other goes to the sensor. The sensor is attached to the evaporator tube. To remove it for inspection, you need to remove the retaining clip or release the spring. Sometimes the sensor is simply inserted into the socket and is held in place due to the tightness of the fit.
When reinstalling, make sure that the sensor fits tightly to the surface of the tube. Poor contact will result in incorrect temperature readings. Use thermal paste if the design of your model allows it, although most budget refrigerators Atlant use direct metal-to-metal contact through a clamp.
Fault diagnosis: table of symptoms and causes
Understanding the symptoms helps you quickly determine what the problem is It is in the sensor, and not in the compressor or thermostat. Below is a table that will help classify the symptoms of a malfunction.
| Symptom | Probable cause | Action |
|---|---|---|
| Thick layer of ice on the evaporator | The sensor does not detect low temperature | Check the resistance of the sensor |
| The refrigerator works without stopping | The sensor is "stuck" in the open state | Replace the defrost sensor |
| Water at the bottom cameras | Defrost cycle failure, drain overflow | Check the heating element and sensor circuit |
| Error code F5 or F6 on the display | Evaporator sensor malfunction | Diagnostics with a multimeter |
If you observe one of these symptoms, there is a high probability that thermocouple it has failed. However, one should not discount the oxidation of contacts in connectors. In refrigerators operated in damp rooms, the contacts may become covered with an oxide film, which impairs conductivity.
It is also worth checking the integrity of the wires. With frequent defrosting, the insulation can dry out and crack, and the vibration of the compressor can lead to a break in the core inside the insulation. A visual inspection of the wiring from the sensor to the connector is mandatory.
Why do sensors fail?
The main reason for the failure of sensors in Atlant refrigerators is natural wear of the bimetallic plate or a violation of the tightness of the thermistor housing. Constant cycles of heating and cooling, as well as aggressive humid environments, lead to degradation of materials. Sometimes the cause is a power surge in the network, which penetrates the sensitive electronics of the sensor.
How to check the sensor with a multimeter
For accurate diagnostics, you will need a digital multimeter. The test consists of measuring the resistance of the sensor. When cold (at temperatures below -5°C), a working sensor should show a certain resistance, usually in the range from 2 to 10 kOhm (depending on the model). When heated, the resistance should change.
Turn the multimeter into resistance measurement mode (Ohm). Connect the probes to the sensor contacts. If the device shows “1” or “OL” (infinity), it means there is a break in the sensor and it is faulty. If it shows "0", then a short circuit has occurred.
To check the change in resistance, you can hold the sensor in your hand to heat it with body heat, or lower it into a glass of warm water (after protecting the contacts from moisture). The resistance should change smoothly. If the number on the screen remains the same, the element is defective.
⚠️ Attention: Never check the resistance of the sensor connected to the refrigerator control board. You can burn the controller with current from the multimeter probes or get incorrect readings due to parallel circuits. Disconnect the sensor before checking!
If you do not have a multimeter, you can try the elimination method by replacing the sensor with a known good one. This is the most reliable way, but it requires purchasing a new spare part. The cost of a sensor for Atlant usually low, so this approach is quite justified.
Replacing the sensor and assembling the system
The replacement process is simple if you have already reached the evaporator. Disconnect the old sensor from the connector. Install the new element in the same position, ensuring tight contact with the evaporator tube. Secure it with a standard clamp.
Make sure that the wire is not pinched and does not touch the moving parts of the fan (if your model has one). Pass the wire along the existing grooves or use standard clips to fix the harness.
After installing the sensor, reassemble the structure in the reverse order. Install the backsplash and secure the shelves and drawers. Plug in the refrigerator. The first few hours it will gain temperature, during which time the compressor may turn on more frequently - this is normal.
If after replacing the sensor the problem does not disappear (for example, ice continues to grow), it may be faulty Defrost heating element or the control unit. In this case, a more in-depth diagnosis with the participation of a specialist will be required.
Frequently asked questions (FAQ)
Is it possible to temporarily remove the sensor to make the refrigerator work?
Technically, if you short-circuit the sensor contacts (connect them directly), the refrigerator may start working, but this will lead to the defrost system will stop turning on automatically. The evaporator will quickly become overgrown with ice, and after a few days the refrigerator will stop freezing completely. It is not recommended to use this method as a temporary solution, as this creates a load on the compressor.
Which sensor is better to buy: original or analogue?
For refrigerators Atlant universal defrost sensors with similar resistance characteristics are often suitable. However, original spare parts guarantee compliance with geometric dimensions and seating. If you are not sure about the parameters of the analogue, it is better to look for the original by catalog number.
Why does the error light up on the display after replacing the sensor?
Some models Atlant require resetting the error after replacing the part. Try unplugging the refrigerator for 15-20 minutes. If the error remains, it is possible that the new sensor is also faulty or the contact in the connector is poorly installed. Check the reliability of the connection.
Is it necessary to lubricate the sensor installation site?
In the factory configuration, a special heat-conducting lubricant or a tight clamp is often used. When replacing yourself, it is advisable to use a small amount of electronics thermal paste to improve the temperature transfer from the tube to the sensor. This will increase the accuracy of operation.