Sudden stopping the refrigerator Indesit No Frost often confuses the owner, especially when the unit stops freezing for no apparent external reason. If the compressor does not start, hums but does not start, or turns on for a few seconds and immediately stops, the problem most likely lies in the starter protection device. It is thermal relay responsible for protecting the motor from overheating and overcurrent, and its failure is one of the most common causes of breakdown.
Understanding the operating principle of this unit helps not only to diagnose a malfunction, but also to avoid an expensive call to a technician for a simple replacement of a part. In No Frost systems, where the compressor operates in a specific cyclic mode, the load on the protective elements may be higher than in drip systems. The check takes a little time, but requires compliance with safety precautions and the presence of a minimum set of tools.
In this article we will analyze in detail the algorithm of actions that will allow you to independently determine whether the relay is to blame for the refrigerator stopping, or whether the problem lies deeper, for example, in the compressor itself. We will look at visual signs, instrumental diagnostic methods and nuances specific to the brand's technology. Indesit.
The principle of operation and the role of a thermal relay in the system
A thermal relay, often combined into a single unit with a starting relay, is an electromechanical switch that opens the circuit when critical temperatures or currents are reached. Inside the housing there is a bimetallic plate that bends under the influence of heat generated by passing current or a heating element. When the temperature of the compressor motor windings reaches a dangerous value, the plate opens the contacts, preventing the motor from burning out.
In refrigerators Indesit system No Frost this element is critically important, since the compressors here often operate at extreme conditions to maintain a low temperature in the evaporator. If the relay does not open the circuit in time, the windings may burn out, resulting in the need to replace an expensive compressor. Conversely, if the relay opens the circuit too early or does not close it back after cooling, the refrigerator will simply stop working.
It is important to distinguish between the functions of starting and thermal protection, although in modern models they are often combined into one housing. The starting relay supplies voltage to the starting winding only at the moment of start, and the thermal relay controls the current in the main winding during the entire operating cycle. Failure of any of the components leads to similar symptoms, but diagnosis requires checking the thermal characteristics of the bimetallic plate.
⚠️ Attention: The thermal relay is a one-time protection element. If you find that it has worked due to overheating, this is a signal of problems in the system (lack of freon, dirty condenser, compressor wear), and not just a reason to replace the part.
Visual diagnostics and primary signs of malfunction
Before taking up the multimeter, you should conduct a thorough external inspection. Often the nature of the damage is visible to the naked eye. If the relay overheated critically, the plastic housing could melt, turn black, or even burst. In such cases, further checking of the electrical parameters makes no sense - the part must definitely be replaced.
Pay attention to the condition of the contacts inside the housing, if the design allows them to be seen, or to the presence of burning and the smell of burnt insulation in the area where the relay is connected to the compressor. In refrigerators Indesit, oxidation of contacts due to moisture or condensation often occurs, which can also lead to false alarms or, conversely, sticking.
Symptoms indicating a malfunction of the thermal relay usually appear as follows:
- 🔌 The compressor beeps a loud click, buzzes for 1-3 seconds and turns off (protection is triggered).
- 🔥 The body of the thermal relay is excessively hot to the touch even after a long period of inactivity.
- 🔋 No response from the compressor when the refrigerator is turned on, although the indicators are on.
- 💡 The appearance of a characteristic smell of burning or plastic in the rear niche of the refrigerator.
If you observe such signs, there is a high probability that bimetallic plate lost its properties or the contacts inside the relay are burnt. However, similar symptoms can also be observed during an interturn short circuit in the engine itself, so a visual inspection is only the first stage.
Necessary tools and preparation for testing
For high-quality diagnostics, you will need a minimum set of tools, which can be found in many home craftsmen. The main device will be a multimeter (tester) capable of measuring resistance in Ohms and checking the integrity of the circuit (continuity). Without this device, accurate diagnostics is impossible, since it is impossible to determine the internal state of the bimetal “by eye.”
You will also need a flat-head and Phillips screwdriver to remove the protective cover of the compressor and dismantle the relay itself. In some models Indesit, the fastenings may be specific, so it is useful to have pliers or wire cutters on hand if you need to carefully bite off the clamps (although it is better to unclench them).
It is extremely important to ensure safety before starting work:
- 🛑 Be sure to disconnect the refrigerator from the power supply by removing the plug from sockets.
- ⏳ Allow the compressor to cool completely (at least 30-40 minutes) so that the thermal relay returns to its original state.
- 🧤 Use dielectric gloves or dry hands to avoid electric shock if accidentally turned on.
Preparation of the workplace also plays a role Role: Provide good lighting to the back of the refrigerator. Often the compressor niche is dark and dusty, which makes it difficult to see the markings of parts and the condition of the wires. Wipe the area around the compressor with a dry cloth to prevent dust from getting inside the contacts.
Step-by-step instructions for removing the relay
The process of removing the thermal relay in refrigerators Indesit No Frost is standardized, but requires care. First, remove the back cardboard or metal panel covering the compressor compartment. It is usually secured with several screws or latches.
Locate the compressor (the black barrel-shaped unit at the bottom). On its protruding rod or on the side, depending on the model, there is a plastic box - this is the start-up relay. It is put directly on the three contact pins coming out of the compressor housing.
To dismantle, perform the following steps:
- Take a photo of the wire connection diagram so as not to confuse anything during assembly.
- Carefully disconnect the wires suitable for the relay (if they are connected through terminals, and not inserted into the housing).
- Remove the retaining metal bracket or spring, if it holds the relay to the compressor housing.
- Remove the plastic casing of the relay upward or to the side (depending on the design).
After removing the casing, you will see the insides: the starting coil, bimetallic strip and contacts. The thermal relay is often a separate element in the form of a “pill” or plate with two contacts inserted into the housing. Carefully remove it, remembering the polarity of the connection (input and output).
⚠️ Attention: Do not use excessive force when removing the relay. The plastic becomes brittle over time and can burst, and the contacts on the compressor are very thin and break off easily.
☑️ Check before diagnostics
Testing methods with a multimeter: resistance measurements
The most reliable way to check thermal relay is to measure its resistance. Switch the multimeter to resistance measurement mode (200 Ohm or 2 kOhm range). In a cold state (after cooling), the contacts of the thermal relay should be closed, that is, the device should show a resistance close to zero (0.1–2 Ohms).
If the multimeter shows one or infinity (open circuit) on a cold relay, it means that the bimetallic plate does not close the contacts or they are heavily oxidized/burnt. This relay is faulty and requires replacement. However, if the resistance is normal, this does not guarantee serviceability, since the relay may not open when heated.
For a deeper check, you can carefully heat the relay. The critical response temperature for most Indesit relays is 125-135°C. Heating can be done with a hairdryer (careful not to melt the plastic) or by dipping the contacts in hot oil (method for experienced ones). When heated, the resistance should increase sharply to infinity (open circuit). After cooling, drop to zero again.
It is also worth checking the integrity of the starting winding if it is built into a common unit. The resistance between the contacts must correspond to the specifications (usually from 20 to 60 Ohms for the starting winding and 10-30 Ohms for the operating winding, depending on the power of the compressor). A short circuit to the housing (short circuit) indicates an insulation breakdown.
Why does the relay heat up?
The thermal relay heats up during operation - this is normal. It transfers heat from the passing current to the bimetallic plate. However, if the relay body becomes hot to the point where it is impossible to touch it with your hand in a second, this may indicate poor contact inside or an overload of the compressor.
Table of typical values and faults
For ease of diagnosis, below is a table with typical parameters that can be found when checking components of the starting system in refrigerators Indesit. Remember that the values may vary slightly depending on the specific compressor model (Aspera, Danfoss, Embraco).
| Check parameter | Normal value | Fault symptom | Probable cause |
|---|---|---|---|
| Thermal relay resistance (cold) | 0.1 - 2.0 Ohm | Infinity (∞) | Bimetallic plate breakage, burnt contacts |
| Thermal relay resistance (heated) | Infinity (∞) | 0 Ohm remains | Contact sticking, loss of elasticity of the plate |
| Resistance starting winding | 20 - 60 Ohm | 0 Ohm or ∞ | Interturn short circuit or winding break |
| Working winding resistance | 10 - 30 Ohm | 0 Ohm or ∞ | Insulation breakdown or break |
| Resistance between contacts and housing | Infinity (∞) | Any value | Breakage to the housing (life-threatening!) |
By analyzing the data obtained, you can accurately determine whether only the relay needs to be replaced or the problem is more serious. For example, if the resistance of the windings is normal, and the relay “rings” as if it is working, but the refrigerator still does not start, the compressor itself may be jammed.
In such cases, replacing the relay will only give a short-term effect or will not help at all. Sometimes the old relay is replaced with a universal one, selecting it according to the operating current indicated on the marking (for example, 1.4A, 1.8A). Installing a relay with an inappropriate current can lead to either frequent false shutdowns or combustion of the compressor.
Replacing the relay and checking the functionality of the system
If diagnostics confirm a malfunction, you must purchase an analogue. For Indesit, universal relays of the PTC series (starting) and thermal protection of the corresponding rod diameter and current are often suitable. When installing a new element, make sure that it fits tightly on the contacts of the compressor and in the housing.
Assemble the structure in the reverse order: install the relay, secure the fixing bracket, connect the wires according to the photo taken earlier. Make sure the wires do not touch hot parts of the compressor. Close the protective compartment cover.
After assembly, turn on the refrigerator and listen:
- 🔊 There should be a clear click and the compressor starts.
- 🌬️ After 5-10 minutes, the back wall inside the freezer should start cool down.
- 🔇 Operation should be smooth, without buzzing and repeated shutdown clicks.
If the compressor starts and runs smoothly, it means diagnostics and repairs were successful. If the situation repeats (clicking and stopping), perhaps the new relay also does not fit the parameters, or the problem lies in the engine itself, which requires more complex repairs or replacement.
⚠️ Attention: The characteristics of compressors and protective devices may vary even within the same line of refrigerators. Always check the markings on the old relay with the parameters of the new one before installation.
Common mistakes during self-diagnosis
One of the common mistakes is an attempt to “revive” a thermal relay by stripping the contacts or bending the plate. In modern sealed housings, this is almost impossible to do efficiently, and a violation of the calibration of the bimetal will lead to the protection not working at the right time, and the compressor will burn out.
Another mistake is ignoring the cause of overheating. If the relay burns out, it means that the compressor was operating in extreme mode. By simply replacing the relay, you risk getting a new breakdown in a month. It is necessary to check the ventilation around the compressor, the cleanliness of the condenser (the black grille at the back) and the level of refrigerant in the system.
Also, users often confuse the start and thermal relays, changing one instead of the other. Although they are adjacent, their functions and internal structures are different. The starting relay (often ceramic or with a coil) is responsible for the start, and the thermal (bimetallic) is responsible for protection. In some prefabricated blocks they are combined, and the entire assembly has to be replaced.
When you need to call a professional technician
Despite the apparent simplicity, there are situations when independent repairs are impractical or dangerous. If after replacing the relay and checking the electrical circuit the compressor still does not start, the problem may be in the mechanical part of the engine or in the refrigerant circulation system.
Call a technician if:
- 🛠️ You find a freon leak (oily spots, hissing, lack of cold when running compressor).
- 🔌 The compressor hums, but does not start even with a new relay and starting device (possibly jammed).
- 🔥 There are signs of insulation breakdown (breaks out the circuit breakers in the panel, current is felt on the case).
- 🧊 The No Frost system does not freezes, and an ice coat has formed on the evaporator (the problem is in the sensors or heating element).
Professional diagnostics using a pressure manifold and a leakage tester will allow you to accurately determine the cause and cost of restoration. In some cases, it is cheaper and more reliable to replace the entire compressor than to try to revive the old one.
Is it possible to temporarily remove the thermal relay to make the refrigerator work?
Absolutely not. Removing the thermal relay will leave the compressor unprotected. With any overload or voltage surge, the motor windings will burn out instantly, which will lead to expensive repairs. In addition, it is a fire hazard.
Why does a new relay burn out after a few days?
This indicates that the reason is not in the relay itself, but in the operating conditions of the compressor. Possible: freon leak (the compressor runs non-stop and overheats), clogged capillary system, thermostat malfunction or poor ventilation around the refrigerator.
Where can I find the markings of a suitable relay for Indesit?
The markings are usually applied to the side or top of the plastic housing of the old relay. Look for codes like "TA", "Klixon", "3MP" or current numeric values (eg 1.4A, 2.0A). Also, the part number can be found in the electrical diagram of the refrigerator.
Does unstable voltage in the network affect the combustion of the relay?
Yes, low voltage causes the compressor to consume more current to start and operate, which leads to overheating and thermal protection. To protect equipment in such cases, it is recommended to use a voltage stabilizer.