Equipment owners Ariston often face a situation when the chamber stops cooling food or, conversely, begins to freeze them. In most cases, the cause of malfunctions of the No Frost or static cooling system is failure temperature sensor. This small element is responsible for transmitting data about the current thermal condition to the electronic control module.
Understanding exactly where thermistor is located in your model allows you to carry out initial diagnostics without calling a technician. The location of the sensor may vary significantly depending on the year of manufacture of the device and the type of defrosting system. In older models it can be built into the evaporator, and in new ones it can be placed in the air duct.
Independent search and replacement of this element requires care, since the plastic parts of the case become fragile at low temperatures. Before starting any work, you must completely disconnect the unit from the power supply by unplugging the plug from the socket. Ignoring this rule may result in electric shock or damage to the electronics.
Principle of operation and role of the sensor in the system
The main function of the sensor, or thermistor, is to continuously monitor the temperature inside the refrigerator or freezer. The device is a resistor whose resistance changes depending on the degree of heating or cooling. The electronic control unit reads these readings and makes a decision to turn the compressor on or off.
If the sensor transmits incorrect data, the system does not work correctly. For example, if the temperature reading is too high, the compressor will run continuously, causing food to freeze. In the opposite situation, when the sensor “thinks” that the chamber is colder than it actually is, the motor may not start at all.
In refrigerators Ariston with a system No Frost thermistors also control the evaporator defrosting process. They signal the heating element about the need for heating to melt the ice, and turn off the heater when the temperature reaches a predetermined limit. A failure in this chain leads to the formation of an ice coat and blocking of air channels.
⚠️ Attention: Incorrect operation of the sensor often imitates symptoms of a freon leak or compressor failure. Before ordering expensive repairs of complex equipment, make sure that the sensors are in good working order.
The accuracy of the readings is critical for energy saving. A serviceable one thermistor allows the refrigerator to operate in optimal mode, saving energy. A worn element can cause the unit to consume 20-30% more electricity without a visible improvement in the quality of cooling.
Symptoms of a thermistor malfunction
You can determine that the problem lies in the sensor by a number of characteristic signs. Most often, users notice that food in the refrigerator compartment begins to spoil faster than usual or, conversely, vegetables freeze at the back wall. This is the first signal that temperature control is broken.
Another obvious symptom is the continuous operation of the compressor. If the motor hums without interruption, but it is warm inside, or it does not turn on at all, although it is warm in the chamber, it is worth checking the sensor circuit. The electronics may simply “not see” the real state of the system.
- 🌡️ An error appears on the display (if there is one) or the temperature indicator flashes, indicating a failure in the control system.
- ❄️ Excessive ice forms in the freezer, even with a working No Frost system, due to a cycle failure defrost.
- 🔊 The compressor makes unusual sounds or operates jerkily, constantly trying to compensate for incorrect sensor readings.
Sometimes the malfunction manifests itself intermittently, that is, it appears and then disappears. This may be due to oxidation of the contacts in the sensor connector. In such cases, lightly tapping the case or vibration may temporarily restore contact, but the problem will soon return. It is important to note that similar symptoms can occur with a malfunction in mechanical models. However, in modern refrigerators
It is important to note that similar symptoms can occur if there is a malfunction thermostat in mechanical models. However, in modern refrigerators Ariston most often they use electronic thermistors, which require checking with a multimeter.
Where to look for the sensor: main locations in Ariston models
Location of the temperature sensor in refrigerators Ariston not universal and depends on the specific series. In most models with the No Frost system, the main air flow sensor is located inside the freezer compartment. It is usually hidden behind a plastic panel on the back or side wall.
To access it, you often have to remove shelves and drawers. In some modifications, the sensor is built directly into the evaporator housing, which requires deeper disassembly. In two-compartment models, the second sensor may be located in the refrigerator compartment, often near the back wall or in the air duct area.
In models with a drip defrosting system, the sensor can be located in a special hole on the back wall of the refrigerator compartment. It does not come into direct contact with food, but measures the air temperature. It is important not to confuse it with the condensate drain hole.
If you cannot find the sensor visually, refer to the technical documentation for your model. Service manuals Ariston contain diagrams with precise locations for each node. Without a diagram, it is easy to damage the fragile plastic latches of the panels.
Instructions for dismantling and accessing the sensor
The process of gaining access to the sensor requires sequential steps. First, you need to completely defrost the refrigerator if there is ice in the compartment. Working with frozen plastic parts increases the risk of their breakage.
☑️ Preparation for disassembly
Remove the protective panel covering the evaporator or air ducts. It is usually secured with plastic clips and a few screws. Be careful: the plastic becomes brittle after prolonged use and can crack if handled carelessly.
Locate the wire going to the evaporator or to the air duct. The temperature sensor is often mounted in a metal or plastic sleeve. Carefully remove it by pulling on the housing, but not on the wires. A sharp tug can break thin wires.
⚠️ Attention: When removing the fan or evaporator panel, make sure that you do not damage the wires going to the defrost heating element. Their damage may cause a short circuit the next time you turn it on.
After removing the sensor, inspect its installation location. There should be no signs of corrosion or moisture. If the sleeve is dirty, carefully clean it so that a new or tested sensor shows the correct temperature.
Diagnostics and testing with a multimeter
To check the serviceability of the thermistor, you need multimeterswitched to resistance measurement mode (Ohms). Sensors Ariston usually have a resistance of about 5-10 kOhm at room temperature, but the exact value depends on the model. As it cools, the resistance should increase.
Connect the multimeter probes to the sensor contacts. If the device shows an open circuit (infinity) or a short circuit (zero), the part is clearly faulty and requires replacement. If there is resistance, but does not change when heating or cooling, the sensor must also be replaced.
For more accurate diagnostics, you can place the sensor in a container with cold water (without soaking the wires) and monitor the change in readings. The resistance should gradually increase as it cools. Sharp jumps or lack of response indicate degradation of the element.
Table of typical resistances
Typical values for Ariston thermistors: at +25°C - about 5-6 kOhm, at 0°C - about 15-16 kOhm, at -18°C - about 40-50 kOhm. Values may vary depending on the batch and specific model.
In some cases, the problem lies not in the sensor itself, but in the wires going to it. Test the circuit from the sensor connector to the control board. Often the wires break at the points of bends or exit from the plastic case.
Table of correspondence and replacement of components
When selecting a replacement, it is important to take into account not only the geometric dimensions, but also the resistance rating. Using an unsuitable analogue will lead to incorrect operation of the refrigerator. Below is a table with approximate parameters for common models.
| Model / Series | Location | Sensor type | Resistance (25°C) |
|---|---|---|---|
| Ariston MBAA | Freezer compartment, behind the panel | NTC thermistor | ~5.5 kOhm |
| Ariston RM | Refrigerator compartment air duct | NTC thermistor | ~6.0 kOhm |
| Ariston No Frost | In the evaporator sleeve | NTC thermistor | ~10 kOhm |
| Ariston Quattro | Rear wall, upper corner | NTC thermistor | ~5.0 kOhm |
When purchasing a new part, pay attention to the length of the wire and the type of connector. If the connector is different, it can be carefully replaced by using heat shrink to insulate the connections. The main thing is to ensure that the contact is sealed so that moisture does not get inside.
Installation is performed in the reverse order. Make sure the sensor is firmly seated in its socket. If it dangles, the temperature readings will be incorrect, since the sensor will measure the air temperature in the chamber and not in the heat exchange zone.
Frequent errors when replacing and setting
One of the common mistakes is ignoring the need for complete defrosting before replacement. An attempt to replace a sensor in a “warm” refrigerator that has just been defrosted artificially can lead to the system immediately going into error or the defrosting cycle being disrupted.
Also, users often forget to reset the error in the electronic module after replacing the part. In some models Ariston you need to perform the procedure reset or simply pause without power for 10-15 minutes for the controller to recalibrate the data from the new sensor.
- 🔌 Do not connect the new sensor “in weight” without fixation to check operation. This may cause a short circuit if the contacts touch metal parts.
- 🧊 Do not use regular glue to fix the sensor in the sleeve. It will lose its properties during heating and cooling cycles. It is better to use standard latches or heat-resistant sealant.
- 📏 Do not cut the sensor wires too short. The length of the wire is designed with a margin for convenient installation, and its lack will create tension that can tear the part out of the socket.
If after replacement the problem does not disappear, it is possible that it is not the sensor itself that is faulty, but the control board, which does not process the signals correctly. In this case, a more in-depth diagnosis of the electronics is required.
⚠️ Attention: Technical characteristics and location of components may vary slightly depending on the year of production. Always check the markings on the part installed in your refrigerator.
Questions and answers (FAQ)
Is it possible to temporarily short-circuit the sensor to make the refrigerator work?
Shorting the sensor (simulating a low temperature) will force the compressor to work constantly. This is an emergency measure that can lead to defrosting of food in the refrigerator compartment and freezing of the evaporator. This method can only be used for short-term diagnostics.
Where to buy an original temperature sensor for Ariston?
It is better to look for original spare parts in authorized service centers or specialized stores of spare parts for household appliances. When ordering, use the exact model number of the refrigerator or the article number of the old part.
Why does not the new sensor solve the temperature problem?
There may be several reasons: a malfunction of the control board, a freon leak, problems with the fan or defrost heating element. It is also possible that a sensor with an inappropriate resistance rating is installed.
How long does a temperature sensor in a refrigerator last?
The average service life of a thermistor is 5-7 years, but it can fail earlier due to power surges, moisture or mechanical damage during defrosting.