Sudden cessation of compressor operation or its characteristic humming without starting are signals that refrigeration equipment owners cannot ignore. Often the cause of a breakdown is not the motor itself, but a small but critical element of the electrical circuit responsible for starting the engine. In brand refrigerators Indesit this part fails quite often due to power surges or natural wear and tear of materials.
Diagnostics of this unit does not require complex equipment, but is required to understand whether you need to call a technician or can handle it yourself. Start relay supplies the necessary impulse to the compressor windings, allowing it start. If this process is disrupted, the refrigerator stops cooling, and food begins to deteriorate.
In this article we will look in detail at how to determine the malfunction, what tools you will need and what to look for during a visual inspection. You will learn to distinguish a burnt part from other breakdowns, which will save time and money on repairs.
Signs of a faulty starting device
The first alarm bell is usually sound. If you hear the engine struggling to start, making a beeping noise, and then a clicking sound and silence, the problem is most likely an electrical issue. This is a classic symptom when starting winding does not receive the required impulse.
Another obvious sign is the complete failure of the compressor to turn on when the light bulb inside the chamber is on. The lamp is on, which means that voltage is supplied to the network, but the engine is silent. Sometimes you can notice that the motor housing gets very hot, although the unit itself does not work.
⚠️ Attention: If after several attempts to start the compressor becomes very hot, let it cool completely (at least 2-3 hours) before re-diagnosis. Working with a hot motor is dangerous and can lead to false measurement readings.
It is also worth listening to the nature of the clicks. The sound should be clear and unmistakable. If you hear a series of quick clicks or crackling sounds, this may indicate sticking contacts or destruction of the internals of the mechanism.
Sometimes the breakdown is accompanied by knocking out plugs or circuit breakers in the panel. This happens if there is a short circuit inside the part. In this case, further switching on the equipment without checking can be dangerous.
Necessary tools and preparation
Before starting disassembly, it is necessary to prepare the workplace and tools. You don't need a complex professional set, but basic equipment should be on hand. The main thing is to ensure the safety and accuracy of measurements.
The main tool will be multimeter (tester). It is this that will allow you to accurately determine the integrity of the windings and the presence of a short circuit. Without this device, diagnostics will be only approximate.
To access the part you will also need:
- 🔧 Screwdriver (Phillips or flat, depending on the fastening of the casing).
- 🔨 Pliers (for carefully remove the terminals).
- 🧤 Dielectric gloves (to protect against residual voltage).
- 📸 Smartphone (to photograph the connection diagram before removal).
It is important to disconnect the refrigerator from the electrical outlet before starting any work. Even if you simply remove the cover, there is no risk of accidentally touching live parts. It is also recommended to move the unit away from the wall to provide easy access from the rear.
If you have a model Indesit with a built-in No Frost system, access may be slightly difficult due to plastic panels. Be careful with the latches so as not to break them when dismantling.
Dismantling and visual inspection of the relay
After turning off the power and moving the refrigerator away, find the compressor. This is the black barrel-shaped unit at the lower rear of the case. There is a plastic box attached to the side or top of it - this is our desired device.
Remove the protective cover, if there is one. It is usually held in place by latches or a single screw. Carefully disconnect the wires going to the contact group. Here it is extremely useful to take a photo so that during assembly you do not confuse the contacts contacts.
The relay itself is removed from the compressor rod by gently shaking it. It is put directly on the motor terminals. After removal, carefully inspect the body of the part from all sides.
What to look for during inspection:
- 👀 Presence of melted plastic or traces of burning.
- 👀 Oxidation or blackening of contact pads.
- 👀 Cracks on case or leakage.
- 👀 Presence of foreign odor (scorched insulation).
If a black coating is visible inside the case or a burning smell is felt, the part definitely requires replacement. However, even visually, the whole device may be faulty inside, so we move on to an instrumental test.
Testing with a multimeter: step-by-step algorithm
The most accurate diagnostic method is to test the contacts using a tester. Switch the device to resistance measurement mode (Ohms). If you have an analog device, do not forget to calibrate the pointer.
First check the circuit between the input contacts. The probes are applied to the terminals that come from the power cord. The resistance should be close to zero if the circuit is closed, or infinity if open, depending on the relay type and condition. For electromagnetic relays in a cold state, the contacts are open.
Then we check the coil. The coil winding resistance must be within certain limits. If the device shows “1” (infinity) or “0” (short circuit), the coil has burned out.
An important point is to check for breakdown. We place one probe on any contact, and the second on the metal body of the relay. The device should show infinity. If there is at least some resistance, then the insulation is broken and the part cannot be used.
☑️ Relay diagnostics
Thermal relays (tablets) are characterized by a change in resistance when heated. Checking the cold state may show normal, but when heated, the contacts may not open. Therefore, if there are no visual defects and the refrigerator does not work, it is often easier to replace the part, since it is inexpensive.
Table of normal resistance readings
For ease of comparison of measurement results, we provide approximate data. Please remember that the values may vary slightly depending on the specific compressor model Indesit (for example, series FG or NL).
| Test type | Normal reading | Fault symptom | Probable cause |
|---|---|---|---|
| Coil resistance | 30 - 60 Ohm | 0 Ohm or infinity | Open or shorted turns |
| Contacts (cold state) | Infinity (open) | 0 Ohm (closed) | Contact sticking |
| Breakage to the body | Infinity | Any value | Insulation failure |
| Thermal release | 0.1 - 1 Ohm | Infinity | Burnt bimetallic plate |
If your measurements differ radically from the tabular data, there can be no doubt about the need for replacement. Even if the deviations are small, but the operation of the refrigerator is unstable, it is better not to risk it.
It is worth noting that for different types of relays (RT, RKT, 3-pin, 4-pin), the wiring diagram may have nuances. Always check the technical documentation for the specific unit, if available.
⚠️ Attention: Technical characteristics of compressors may vary depending on the year of manufacture and modification. The values indicated in the table are averaged for standard models. For an accurate diagnosis, check the product data sheet or the official data of the manufacturer.
Typical errors during diagnosis and replacement
A common mistake for beginners is ignoring the state of the contacts on the compressor itself. Even a new relay will not work if the motor terminals are oxidized or burnt. Be sure to sand them down with fine sandpaper before installation.
Another problem is incorrect orientation during installation. The relay fits onto the compressor rod in only one position. Usually on the case there is a marking UP (top) or an arrow indicating the direction. If you confuse the top and bottom, the mechanism will not work.
Some craftsmen try to clean the burnt contacts with sandpaper and the old relay. This can only be done as a temporary measure. The structure of the metal is damaged, and after a short time the problem will return, perhaps with damage to the compressor.
Why can’t you ignore clicks?
Frequent clicks indicate that the relay is trying to start the motor, but cannot. If you ignore this, the compressor starting winding will burn out, and repairs will cost 3-4 times more than replacing the relay.
It is also important to check the capacitor, if there is one in the circuit. A swollen or leaking capacitor can put a load on the relay, leading to its rapid failure. Change these elements in a comprehensive manner if they are located nearby.
Choice of replacement and installation features
When purchasing a new part, it is important to know the exact markings of the old one. Numbers and letters are usually stamped on the case (for example, RTK-XX or 1712). If it is difficult to find an exact analogue, you can use universal models, but they require careful configuration.
Universal relays often have several pairs of contacts. They must be connected strictly according to the diagram that comes with the kit. An error in the connection can lead to instantaneous combustion of the new part.
The installation process is simple: we put the part on the rod until it stops, then we connect the wires to the contact group. Make sure that the wires do not touch hot parts of the compressor or each other.
- ✅ Make sure that the relay is seated tightly and does not dangle.
- ✅ Check that the wires are securely fixed in the terminals.
- ✅ Make sure that the housing does not interfere with the installation of the protective cover.
After assembly, turn on the refrigerator. Normal startup should occur a few seconds after the characteristic click. The motor should work smoothly, without buzzing or vibration.
Prevention and long-term operation
To extend the life of the new relay and compressor, ensure good ventilation of the back wall of the refrigerator. Do not move the unit close to the wall, leave a gap of at least 10 cm for air circulation.
Regularly wipe the rear panel from dust. A thick layer of dust acts as a heat insulator, the compressor overheats, the thermal relay trips more often, and the service life of the part is reduced.
Also monitor the condition of the door seals. If the door does not close tightly, the compressor works without interruption, which leads to its overload and premature wear of the starting mechanism.
⚠️ Attention: If, after replacing the relay, the refrigerator stops starting again after a short time, the problem may be deeper. There may be an interturn short circuit in the compressor windings or a thermostat malfunction. In this case, professional diagnostics are required.
Following these simple rules will help your Indesit last for many years without expensive repairs. Remember that regular inspection of equipment allows you to identify problems at an early stage.
Questions and answers (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Technically, you can start a compressor by applying voltage directly to the working winding, but doing this is strictly not recommended without special skills. This is life-threatening and can completely kill the motor, since the overheating protection will not work.
Why does a new relay burn out after a week?
There may be several reasons: power surges in the network, a malfunction of the compressor itself (turn-to-turn short circuit), incorrect installation or the use of a low-quality analogue. Also check the thermostat - if it is “stuck”, the compressor works without rest.
What is the difference between the RT and RKT relays?
The main difference is in the design and principle of operation. RT (thermal) operate on the principle of expanding a bimetallic plate, and RKT (start-up protection) often combine the functions of a starting and protective device with different sensitivity. They are not always interchangeable without modifications.
A cracking sound is heard inside the relay, what does this mean?
Crackling usually means that the contacts inside are burnt, oxidized, or the spring-loading mechanism is destroyed. In this case, the part cannot be repaired and requires mandatory replacement.
How much does it cost to replace the relay in the service?
The cost consists of the price of the part itself and the work of the technician. The part is inexpensive, but calling a specialist and diagnostics can cost more than the spare part itself. Self-replacement saves up to 70% of costs.