If your refrigerator Ariston stops freezing normally, ice forms on the back wall of the freezer, and the compressor works non-stop - the problem may lie in faulty defrost sensor. This small but critical element is responsible for the timely activation of the evaporator defrost system. Without its correct operation, the refrigerator turns into an ice monolith, and food spoils due to unstable temperature.
In this article we will look at where exactly the defrost sensor is located in refrigerators Ariston of different series (including popular Hotpoint-Ariston, Indesit under the Ariston brand and models with the system No Frost). You will learn how to find it without disassembling the entire unit, what tools are needed for diagnostics, and what to do if the sensor fails. And for those who are afraid of making a mistake, we have prepared detailed layout diagrams with photographs of real refrigerators.
We warn you right away: searching for a defrost sensor requires care. In some models it is hidden behind the panels, and to get to it you will have to remove several fasteners. But don’t worry - we have described the process so that even a beginner can handle it without errors.
What is a defrost sensor and how does it work?
A defrost sensor (also called defroster or defrost thermistor) is a temperature sensor that controls the heating of the evaporator during the cycle defrosting. In refrigerators Ariston with a system No Frost it works in conjunction with a defrost timer and heating element:
- 🔄 The defrost timer starts a defrost cycle every 6-12 hours (depending on the model).
- 🔥 The defrost heating element heats the evaporator to melt the ice.
- 🌡️ Defrost sensor monitors the temperature of the evaporator and turns off the heating element when the ice is completely melted.
If the sensor is faulty, the heating element either does not turn on (ice builds up, blocking air circulation) or does not turn off (overheating of the evaporator, risk of compressor failure). In refrigerators Ariston without No Frost (drip system), a defrost sensor may be absent - instead, a timer or mechanical thermostat is used.
Signs of a defrost sensor failure:
- ❄️ A thick layer of ice (more than 1-2 cm) forms on the back wall of the freezer.
- ⚡ The compressor runs non-stop or turns on too much often.
- 🌡️ The temperature in the refrigerator compartment rises above +5°C, despite the maximum settings.
- 🔊 An unusual noise appears (crackling, gurgling) due to an icy fan.
Where to look for the defrost sensor in different models Ariston
The location of the sensor depends on refrigerator series the type of defrosting system. In models Ariston c No Frost it is always located next to the evaporator - either on the evaporator itself or on its body. In refrigerators with a drip system, the sensor may be absent or integrated into the control board.
We have collected data on the most common series:
| Series/model | System type | Sensor location defrost | Notes |
|---|---|---|---|
| Hotpoint-Ariston NBC, NF | No Frost | On the evaporator of the freezer, under the plastic cover | Often attached to a clip next to the heating element |
| Ariston MBA, MBF | No Frost (Full No Frost) | Inside the air duct, behind the back panel of the freezer | It is necessary to remove the panel and insulation |
| Ariston RM, RMB | Drip system | Absent or built into the control board | Problems with defrosting are usually associated with the thermostat |
| Ariston HBM, HBT | No Frost (freezer) + drip (cold. camera) | Only in the freezer compartment, on the evaporator | There is one sensor, but it is responsible for both chambers |
In models Ariston with electronically controlled (display on the door) sensor defrosting is often combined with evaporator temperature sensor. In this case, it looks like a small plastic cylinder with two wires, attached to the evaporator with adhesive tape or a clip.
Defrost sensor location diagrams with photos
To make it easier for you to navigate, we have prepared visual diagrams for popular models. Please note: the appearance of the sensor may be slightly different, but the mounting principle and location remain similar.
Scheme for Ariston Hotpoint-Ariston NBC/NF (No Frost)
In these models, the defrost sensor (indicated by a red circle) is located on the evaporator of the freezer, under the plastic cover. To get to it:
1. Unplug the refrigerator.
2. Remove all food from the freezer.
3. Remove the back panel of the freezer (it is secured with 4–6 screws).
4. Under the plastic cover of the evaporator you will see a sensor - a small white or black cylinder with two wires.
5. The wires usually lead to the control board (it is located at the bottom of the refrigerator, behind the decorative panel).
In models Ariston MBA/MBF (Full No Frost) the sensor is hidden deeper:
- 🔧 First, remove the back panel of the freezer (unscrew the screws around the perimeter).
- 🧊 Under the panel you will see an evaporator covered with a layer of insulation. Carefully bend the insulation - the sensor is attached to the evaporator tube.
- 🔌 The sensor is connected to the control board with two wires (usually brown and white).
Important! In some models Ariston the defrost sensor can be soldered to the control board. In this case, replacing it requires soldering or completely replacing the board. If you are not confident in your skills, it is better to contact a specialist.
What tools are needed for diagnostics
To check the defrost sensor, you do not need professional instruments - a basic set of tools is enough. Here's what will come in handy:
- 🔧 Phillips screwdriver (PH2) - for removing panels.
- 🔧 Flat screwdriver - may be needed to disconnect the clips.
- 📏 Multimeter (tester) - to check the resistance of the sensor.
- 🧊 Hairdryer (optional) - to speed up defrosting if ice prevents you from reaching the sensor.
- 📸 Phone with camera - to photograph the location of the wires before disconnecting.
If you do not have a multimeter, you can use an alternative test method:
- Unplug the refrigerator from network.
- Get to the sensor and disconnect the wires from it.
- Start the refrigerator without the sensor. If the defrost heating element begins to heat up continuously (the evaporator becomes hot), then the sensor is faulty.
☑️ Preparation for diagnosing the defrost sensor
Critical information: In refrigerators Ariston with electronic control (models after 2015), the defrost sensor can be part of a single sensor unit. In this case, replacing it requires reflashing the control board - independent repair is not recommended.
How to check the defrost sensor with a multimeter
Checking the defrost sensor with a multimeter takes no more than 5 minutes, but requires accuracy. Follow these instructions:
- Unplug the refrigerator unplug and wait until the evaporator thaws (if it is covered with ice).
- Remove the back panel freezer and locate the sensor (see diagrams above).
- Disconnect the connector with wires from the sensor. Usually this is a two-pin connector with a latch.
- Move the multimeter to resistance measurement mode (20 kOhm).
- Connect the probes to the sensor contacts and measure the resistance:
- 🌡️ At room temperature (+20°C) the resistance should be 4–6 kOhm.
- ❄️ If you cool the sensor (for example, put it in the freezer for 10 minutes), the resistance should increase up to 20–30 kOhm.
- 🔥 If you heat the sensor (hold it in your hand or bring it to a lamp), the resistance should drop to 1–2 kOhm.
If the resistance:
- 🚫 Infinity (OL) - open circuit, sensor is faulty.
- 🚫 0 Ohm - short circuit, sensor is faulty.
- 🚫 Does not change when heating/cooling - sensor does not respond temperature, requires replacement.
In some models Ariston the defrost sensor may have three contacts. In this case, the third contact is usually responsible for additional protection (for example, against overheating). Check the resistance between first and second contacts - the third may not respond to temperature changes.
How to replace the defrost sensor yourself
If diagnostics have confirmed a faulty sensor, it needs to be replaced. In most cases, this can be done without calling a technician. Here are the step-by-step instructions:
- Buy a new sensor. For refrigerators Ariston sensors with article numbers are suitable:
C00088300- for models Hotpoint-Ariston NBC/NF.C00324756- for Ariston MBA/MBF.C00193301- universal for many series with No Frost.
Check the article according to the model of your refrigerator (see the sticker on the back wall).
After replacing the sensor, the refrigerator may operate unstably for the first 1-2 hours - this is normal. The system must “get used” to the new sensor. If after a day the problem does not disappear (for example, ice forms again), check:
- 🔌 The correct connection of the connector (are there any mixed up wires).
- 🌡️ The functionality of the defrosting heating element (check its resistance with a multimeter - it should be 20–50 Ohms).
- ⚡ Control board (the fuse or relay may have burned out).
Typical mistakes when finding and replacing a sensor
Even experienced craftsmen sometimes make mistakes when working with a defrost sensor. Here's what you can't do:
- ❌ Ignore defrosting. If you do not remove the ice before replacing the sensor, the new sensor may fail due to overheating of the heating element.
- ❌ Mix up the sensors. The refrigerator Ariston may have 2-3 temperature sensors (for the refrigerator, freezer and evaporator). Do not mix them up!
- ❌ Use force when removing panels. Plastic clips break easily, and spare parts are difficult to find.
- ❌ Forget about tightness. After assembly, make sure that all panels fit tightly - otherwise condensation will build up.
Another common mistake is purchase of a non-original sensor. Cheap analogues may give incorrect readings, causing the refrigerator to not work correctly. For example, a sensor with an incorrect temperature characteristic may turn on the heating element too early or too late, which will lead to icing or overheating.
If after replacing the sensor the problem does not disappear, another element of the defrosting system may be faulty:
| Symptom | Possible cause | Solution |
|---|---|---|
| The heating element does not heat, the ice does not melt | The defrosting heating element has burned out | Ring the heating element with a multimeter, replace it if it breaks |
| The heating element is heating constantly | The defrost timer is faulty | Check the timer, replace if broken |
| The refrigerator does not turn on after replacement | The sensor wires are mixed up | Check polarity, check the diagram |
| Ice builds up in only one corner | Drain hole clogged | Clean the drain with wire |
Frequently asked questions
Is it possible can you do without replacing the defrost sensor if it is broken?
Technically yes, but this is a temporary solution. You can turn off the sensor and start the defrost heating element manually (for example, through raistats), but this will lead to:
- Overheating of the evaporator (risk of compressor breakdown).
- Increased energy consumption.
- Frequent heating element breakdowns due to lack of control.
It is still better to replace the sensor - it is cheaper than repairing after such "crutches".
How to distinguish a defrost sensor from a temperature sensor?
In refrigerators Ariston sensors differ in:
- Location: the defrost sensor is always on evaporator, temperature sensor - in the chamber (on the wall or ceiling).
- Connector: the defrost sensor usually has two wires (less often three), the temperature sensor has two or four.
- Resistance: the defrost sensor shows 4–6 kOhm at +20°C, temperature sensor - 1–2 kOhm.
How much does it cost to replace a defrost sensor at a service center?
The cost depends on the refrigerator model and region:
- Sensor: 800–2500 rubles (original).
- Foreman's work: 1500–3000 rubles.
- Diagnostics: 500–1000 rubles (sometimes free for repairs).
Total: 2300–5500 rubles. Independent replacement will only cost the cost of the sensor.
What to do if after replacing the sensor the refrigerator still does not freeze?
Carry out comprehensive diagnostics:
- Check Defrost heating element (resistance 20–50 Ohm).
- Ring defrost timer (should click when turning the knob).
- Make sure that fan in the freezer it rotates freely.
- Check fuse on the control board (may be burnt).
If everything the elements are in good order, the problem may be in control board —it is better to entrust its repair to a professional.
Can I use a defrost sensor from another refrigerator?
Only if:
- Articles sensors are the same.
- Refrigerators of the same series (for example, both Hotpoint-Ariston NBC).
- The temperature characteristics are identical (checked with a multimeter).
Using a sensor from another model may lead to incorrect operation of the defrost system.
If you have not found the answer to your question or refrigerator behaves non-standardly (for example, it shows an error on the display), check exact model your Ariston -we will help you deal with the specific problem.