Refrigerators Indesit are deservedly popular due to their reliability and simplicity of design, but even the most reliable equipment breaks down over time. One of the most common problems faced by owners of these units is the formation of an ice coat in the chamber or, conversely, a complete lack of cooling. Often the cause of such symptoms is the failure of the No Frost or drip defrost system, namely a malfunction of the defrost relay.
This small but critical component is responsible for turning the heating element on and off, which melts the ice on the evaporator. If the relay is stuck closed or open, the defrost cycle is disrupted, causing the compressor to overload or freeze the ducts. In this article, we will analyze in detail how to diagnose this unit without resorting to the help of expensive service centers, and what tools you will need to carry out a quality test.
Before embarking on the active phase of repair, you must clearly understand that diagnosing electrical equipment requires compliance with safety rules. Any work inside the refrigerator should be carried out only after the appliance has been completely disconnected from the power supply. Failure to do so may result not only in damage to electronics, but also in electrical shock. Your safety is the number one priority in any repair of household appliances.
The principle of operation and the role of the relay in the defrost system
The defrost relay in refrigerators Indesit performs the function of an automatic switch that controls the operation of the evaporator heating element. In models with the No Frost system, this process is started by a timer, which at certain intervals (usually 8-12 hours) switches the refrigerator to defrost mode. At this moment, the compressor stops, and the relay supplies voltage to the heating element, melting the frost accumulated on the evaporator.
Structurally, the relay is a bimetallic sensor enclosed in a protective housing, often in conjunction with a thermal fuse. Bimetallic plate inside the relay reacts to the temperature of the evaporator: when the ice completely melts and the temperature rises to a certain value (usually about +10...+15°C), the plate bends and opens the circuit, turning off the heating element. If the relay does not open the circuit in time, the heater will work constantly, which can lead to the melting of the plastic parts of the chamber.
⚠️ Attention: Incorrect operation of the defrost relay often leads to the fact that the refrigerator begins to work in increased mode, trying to compensate for the loss of cold due to a frozen evaporator. This dramatically increases energy consumption.
Understanding this cycle is important for correct diagnosis. If you notice that the back wall of the refrigerator compartment is covered with a thick layer of ice, and in the freezer the food has lost its shape due to periodic thawing, this is a sure sign that defrost cycle it is broken. In such cases, checking the relay becomes the first step in troubleshooting.
In some models Indesit the defrost relay is combined with a defrost sensor in a single unit, which simplifies the design, but requires a more careful check of the integrity of the entire bundle. An error in determining the type of relay can lead to the purchase of the wrong spare part, so always check the markings before removing them.
External signs of a malfunction of the defrost relay
You can determine that the problem lies in the defrost relay by a number of indirect signs that appear in the operation of the refrigerator. Often, owners ignore the first “bells”, attributing them to drafts or a loosely closed door, but ignoring the symptoms can lead to more serious and expensive repairs, such as replacing the compressor.
The main indicator of problems is the nature of the ice that forms in the freezer. If the ice is unevenly distributed, or, on the contrary, its amount is excessively large and it blocks the ventilation holes, this indicates a malfunction in the defrosting system. It is also worth paying attention to the operation of the compressor: if it turns on too often or, conversely, works almost non-stop, trying to gain temperature, this may be due to the fact that the evaporator is clogged with ice due to a non-working relay.
Let's look at the main symptoms in more detail:
- ❄️ Thick ice crust: A monolithic piece forms on the evaporator (hidden behind the back panel of the freezer) ice, which blocks the flow of cold air.
- 🌡️ Temperature changes: Products in the refrigerator compartment either freeze or begin to deteriorate due to unstable cooling.
- 💧 Water under the refrigerator: Due to the fact that the ice does not have time to melt within the allotted time or melts too actively, the water does not have time to evaporate in the tray and flows out.
- 🔊 Extraordinary sounds: Crackling or clicking sounds in the area of the freezer, which may indicate thermal expansion of materials or an attempt by the relay to operate.
It is important to note that these symptoms may indicate other problems, such as a malfunction of the defrost timer or the heating element itself. That is why visual inspection and subsequent instrumental diagnostics are mandatory steps. You cannot rely only on external signs, as they are often complex.
If you notice that the back wall of the refrigerator compartment (in models with a drip system) does not thaw for a long time after the compressor is turned off, this may also indicate problems with thermoregulation, although in No Frost systems a separate circuit is responsible for this. In any case, the presence of ice where it should not be is a signal to action.
Preparation for diagnostics: tools and safety
Before you start checking the defrost relay on the refrigerator Indesit, you need to prepare a workplace and the appropriate tool. High-quality diagnostics are impossible “by eye,” so having a basic kit for a home craftsman or specialist is a prerequisite. You should not try to ring the contacts without a suitable device, as this will not give an accurate result.
To carry out the work you will need:
- 🔧 Multimeter: The main tool for measuring resistance and checking circuit integrity. Without it, electronics diagnostics are meaningless.
- 🪛 Screwdriver set: Phillips and flathead screwdrivers of different sizes will be needed to remove panels and dismantle components.
- 🔦 Flashlight: The lighting inside the refrigerator compartment is often insufficient, especially with shelves and panels removed.
- 🧤 Gloves: To protect hands from sharp plastic edges and possible residual cold.
Pay special attention to safety. Before starting any work, the refrigerator must be unplugged for at least 30 minutes. This is necessary so that the capacitors (if there are any in the control circuit) are discharged and so that you do not receive an electric shock. In addition, working with a defrosted unit is safer, since the risk of a short circuit from ingress of water is eliminated.
⚠️ Attention: Never use a knife or other sharp objects to quickly chip away ice before checking. Damage to the evaporator will lead to a freon leak and expensive repairs, which are often not economically feasible.
If you plan to carry out diagnostics in the winter, make sure that the room is warm enough so that the condensation formed during defrosting does not turn into ice on the floor. Prepare rags or towels to catch the water. It is also recommended to find a diagram of your refrigerator in advance Indesit (usually it is located on a sticker inside the chamber or in the technical documentation) in order to know exactly the location of the elements.
Dismantling and visual inspection of the defrost relay
To get to the defrost relay in most models Indesit with the No Frost system, you will need remove the back panel of the freezer. This process may vary depending on the specific model, but the general algorithm of actions remains similar. Be careful with plastic latches, which become brittle at low temperatures and break easily.
The process of accessing the defrost unit is as follows:
- Empty the freezer of food and remove all shelves and drawers.
- Unscrew the screws securing the rear plastic panel. In some models, they may be hidden under decorative plugs.
- Carefully move the panel away. If it is frozen, let the refrigerator sit to defrost naturally. Do not use force.
- Find the evaporator. The defrost relay is usually located in the lower or middle part of the evaporator, often in conjunction with a thermal fuse and a capillary tube.
A visual inspection can immediately answer many questions. Pay attention to the condition of the relay housing: it should not have signs of melting, blackening or cracks. If you see that the plastic is deformed, this is a clear sign that overheating has occurred inside, and the relay definitely needs to be replaced. Also check the integrity of the wires going to the relay: they should not be broken or have damaged insulation.
Often the defrost relay Indesit is a small black or white box attached to the evaporator tube using a metal clamp or clip. In some cases, it may be filled with a compound along with a thermal fuse. If the relay body is swollen or emits an unpleasant burning smell when connected (which is rare, but possible), further operation of the device is prohibited.
If there are no visual defects, this does not guarantee the serviceability of the part. The bimetallic plate inside could simply “get tired” and stop responding to temperature changes, while maintaining the integrity of the case. Therefore, let's move on to an instrumental test.
Checking a relay with a multimeter: step-by-step instructions
The most accurate way to check a defrost relay is to use a multimeter in resistance measurement mode (Ohm). This method allows you to determine whether there is a break in the circuit inside the sensor or, conversely, whether the contacts are stuck. Before starting measurements, make sure that the relay has cooled to room temperature if it has just been removed from a working refrigerator.
To check, follow these steps:
- 🔌 Disconnect the terminals: Remove the wire connectors from the relay contacts. Do not pull on the wires themselves, hold on to the plastic tips.
- ⚙️ Set up the multimeter: Set the switch to resistance measurement mode (usually denoted Ω) to the limit of 200 Ohms or 2 kOhms.
- 📏 Take measurements: Touch the multimeter probes to the relay contacts. Polarity in this case is not important.
- 📊 Analyze the readings: Compare the obtained values with the standard ones.
A normal working defrost relay at room temperature should be open (show infinite resistance or one on the multimeter screen), since at temperatures above +10°C the heater circuit must be turned off. If you see a "0" or close to zero value on the screen at room temperature, this indicates that the contacts are stuck closed and the relay is faulty. If, when the relay is cooled (for example, by putting it in the freezer for 15-20 minutes), the resistance does not become zero (the circuit does not close), then the bimetallic plate does not work.
The table below shows the main states and the corresponding instrument readings:
| Relay status | Temperature | Multimeter readings | Verdict |
|---|---|---|---|
| Service (cold) | Below -5°C | 0 Ohm (Closed) | Normal |
| Good (warm) | Above +10°C | ∞ (Open) | Normal |
| Faulty (break) | Any | ∞ (Always open) | Replacement |
| Faulty (short circuit) | Any | 0 Ohm (Always closed) | Replacement |
It is also important to check the thermal fuse, which is often paired with a relay. It should ring (show zero) always, regardless of the temperature. If the thermal fuse shows a break, it also needs to be replaced, otherwise the defrost circuit will not work even with a new relay.
☑️ Checking the defrost relay
Replacing the faulty relay and typical errors
If the diagnostics showed, that the defrost relay is faulty and needs to be replaced. In refrigerators Indesit this process usually does not cause difficulties if you act carefully. The main thing is to choose an analogue with identical temperature response characteristics. There are no universal relays; the parameters may differ for different models.
Replacement algorithm:
- Purchase a new relay that matches your refrigerator model. The spare part number can be found on the body of the old relay or in catalogs for the refrigerator model.
- Remove the old relay by disconnecting the terminals and removing the mounting clamp.
- Install the new relay in the same place, pressing it tightly to the evaporator tube (heat exchange is important for correct operation).
- Connect the wires according to the diagram or photograph taken earlier.
- Make sure that all connections are secure and the wires do not touch the heating elements.
One of the typical mistakes is poor contact of the relay with the evaporator tube. The relay must fit tightly to the surface to accurately read the temperature. If there is a gap between the sensor body and the tube, the defrost cycle will be disrupted. To improve thermal contact, in some cases it is recommended to use a special heat-conducting lubricant, although the factory equipment often uses simply a tight fit. Indesit Often a simple tight fit is used.
⚠️ Attention: Do not use glue or electrical tape to attach the relay, which may melt or disrupt heat transfer. Use only standard clamps or clips.
After replacement, reassemble the refrigerator in the reverse order, but do not install the products yet. Plug in the unit and let it run idle for several hours. Monitor how the first defrost cycle goes. If after 8-10 hours of operation of the compressor the refrigerator goes into defrosting (a click is heard and the compressor stops humming), then the repair was successful.
What will happen if you install a relay with different temperature parameters?
If you install a relay that opens at a lower temperature, the ice will not have time to completely melt, which will lead to gradual fouling evaporator. If at a higher level, the heating element will heat up longer than necessary, consuming excess energy and heating the chamber.
Sometimes, after replacing the relay, it is necessary to force the defrost cycle to start to make sure it is working. In some models this is done by a combination of buttons, in others it is enough to wait for the natural cycle. If you are not confident in your abilities, it is better to entrust the final assembly and testing to a professional.
Frequently asked questions and answers (FAQ)
Is it possible to temporarily operate a refrigerator with a faulty defrost relay?
You can only operate a refrigerator with a faulty defrost relay in emergency mode and very briefly. Over time, the evaporator will be completely covered with ice, the compressor will work non-stop, which will lead to its overheating and failure. In addition, products may begin to deteriorate due to temperature violations.
What is the difference between the Indesit defrost relay and relays of other brands?
The main difference is the temperature thresholds (closing and opening temperatures) and the geometric dimensions of the housing. Although the operating principle of all bimetallic relays is the same, using an analogue with inappropriate parameters will lead to incorrect operation of the No Frost system.
How often do you need to change a defrost relay?
A defrost relay is a mechanical device, the life of which is limited by the number of operation cycles. On average, the service life of the relay is 5-7 years of active use. However, frequent power surges in the network can significantly shorten this period.
Why does the refrigerator not go into defrost after replacing the relay?
There may be several reasons: the defrost timer (or control module) is faulty, the heating element is burned out, the thermal fuse is broken, or the relay itself is installed incorrectly (no contact with the tube). It is also worth checking the integrity of the wiring between the system components.