The situation when the refrigerator compressor tries to start, emits a short beep or click, and then goes silent, is familiar to many owners of household appliances. Often the culprit of such a malfunction is not the motor itself, but the control electronics, in particular the starter protection device. It is responsible for supplying voltage to the motor windings at the time of start and protecting against overloads. If this element fails, the compressor does not receive the necessary impulse to operate, and the refrigerator stops cooling, although the light inside is on.
Before calling a technician or buying expensive spare parts, it makes sense to conduct an initial diagnosis yourself. To do this, you will only need a minimal set of tools and a basic understanding of electrical circuits. Checking the relay - the procedure is not complicated, but it requires care and compliance with safety precautions when working with electrical appliances. In this article, we will analyze an algorithm of actions that will help determine whether the start regulator is working or needs to be replaced.
It is worth noting that modern refrigerators can be equipped with different types of starting devices. These can be classic induction models with a posistor or more complex electronic modules. The method for checking them has its own nuances, but the basic principle of testing contacts with a multimeter remains the same for most household units. Understanding the physics of the process will help you avoid mistakes when diagnosing.
Design and principle of operation of the starting relay
The starting relay is a small block that is placed on the terminals of the compressor. Hidden inside the case is an electrical circuit that controls the supply of current. Classic electromagnetic models use a coil and a movable core that closes the contacts of the starting winding when voltage is applied. As soon as the motor picks up speed, the current drops and the contacts open. More modern systems often use posistor a thermistor, which changes its resistance when heated, which also ensures that the circuit breaks after start.
In parallel with the starting function, thermal protection is often implemented. It is a bimetallic plate that opens the power circuit when the windings or motor housing become overheated. This prevents the compressor from burning out when jammed or power surges. Malfunction any of these components leads to the refrigerator not starting or working with periodic shutdowns.
It is important to understand that the relay is a consumable item. Its service life is limited by the number of on and off cycles, as well as operating conditions (humidity, voltage surges). Over time, the contacts may burn out, the coil may lose its properties, and the posistor may crumble. That is why diagnostics begin with this particular unit, since replacing it is much cheaper than repairing the compressor itself.
⚠️ Attention: Refrigerant or oil residues may remain inside the relay housing if the seal is broken. Do not forcefully open the case and do not burn old parts, as this can be hazardous to health.
Necessary tools and safety measures
To carry out high-quality diagnostics, you will need a minimum kit for a home technician. The main tool will be multimeter (tester), capable of measuring resistance (Ohm) and checking the integrity of the circuit (continuity mode). It is advisable that the device is in good working order and its batteries are not discharged, otherwise the readings may be incorrect.
You will also need:
- 🔧 Screwdriver (Phillips or flat) for removing the back panel and clamps.
- 🔦 Flashlight for better illumination of the working area in the compressor area.
- 🧤 Dielectric gloves to protect hands (optional, but recommended).
- 📱 Smartphone for photographing the connection diagram before disassembling.
The most important rule is to completely de-energize the device. Before starting any work, you must unplug the refrigerator cord from the outlet. Even if you only plan to remove the relay cover, the risk of touching live parts or creating a short circuit due to careless handling of the wires remains high. Electric current invisible, and neglecting this rule can lead to serious injury.
Let the refrigerator stand turned off for at least 10-15 minutes before starting work. This is necessary so that the capacitors in the starting circuit (if any) are discharged and the hot elements of the compressor cool down. Working with a hot motor is inconvenient and unsafe.
☑️ Preparation for diagnostics
Dismantling and visual inspection of the part
After the refrigerator is unplugged, you need to gain access to the compressor. It is usually located at the lower rear of the case. Remove the metal or plastic panel covering the engine compartment. You will see a view of the black cylindrical tank of the compressor, to the end of which a small plastic box is attached - this is the required relay.
Carefully remove the device from the compressor terminals. It can be held on by latches, brackets, or simply sit tightly on the contacts. If there is a fixing clamp, it needs to be loosened. Be careful not to pull sharply to avoid damaging the associated wires. Before disconnecting the wires, be sure to remember or take a photo of which wire is connected where. Color marking may differ in different models Indesit, Atlant or Beko.
Initial visual inspection often provides 50% of the information about the condition of the part. Carefully examine the case for:
- 🔥 Traces of melting, blackening or soot on the case and contacts.
- 👃 An unpleasant burning smell that may come from the insides.
- 💥 Cracks, swelling or mechanical damage plastic.
- 🌫️ Oxidation of contacts or the presence of a greenish coating.
If you find obvious signs of overheating or destruction of the case, further testing may not be necessary - the part definitely requires replacement. However, if the relay looks intact on the outside, this does not guarantee its serviceability. Internal coil breaks or sticking contacts are not visually visible, so we proceed to an instrumental check.
What do the colors of the wires mean?
Usually a black or blue wire leads to the common winding, red or white to the starting winding, but in different models of refrigerators the colors may vary. Always rely on the diagram in the instructions or the markings on the relay itself, and not just on the color of the insulation.
Multimeter testing technology
To carry out measurements, switch the multimeter to resistance measurement mode (indicated by the Ω symbol) or to continuity mode (speaker symbol). If you have selected the dialing mode, then when the probes are closed, the device should emit a sound signal. This will confirm the serviceability of the probes and batteries.
The verification process depends on the type of relay. For electromagnetic models (with a coil), the algorithm is as follows: connect the probes to the contacts corresponding to the coil terminals. The case often has markings, for example, S (Start) and R (Run) or M (Main). The resistance of a working coil is usually several ohms (from 3 to 30 ohms, depending on the power of the compressor). If the device shows one (infinity), it means that break turns have occurred, and the relay does not work.
Checking contacts for shorting and opening requires a more careful approach. In the initial position (the relay is inverted or lies as on the compressor), the contacts of the starting winding must be open (the resistance is infinite). If you turn the relay over (simulating operation when current flows), the contacts should close (resistance is close to zero, a squeak is heard). The absence of a reaction indicates mechanical jamming or burning of the contacts.
For models with a posistor, the check is even simpler. A posistor in a cold state has a small resistance (tens of ohms). When heated (which is difficult to check without special equipment at home), it should grow indefinitely. If the multimeter shows zero or, conversely, immediately infinity on a cold element, the posistor is faulty. Often it is enough to simply shake the relay: if something rattles inside, it means the posistor has crumbled.
⚠️ Attention: When measuring resistance, do not touch the metal parts of the probes with your fingers. The resistance of the human body can distort the readings of the device, especially at high measurement limits.
Table of typical faults and symptoms
To systematize the data obtained, it is convenient to use a summary table. It will help compare the device readings with the probable cause of the breakdown. Remember that the exact resistance values depend on the specific model of the refrigerator and the power of its engine.
| Multimeter readings | Contact/coil condition | Probable cause | Solution |
|---|---|---|---|
| ∞ (Unit) | Open coil circuit | Burned winding | Replacement of relay |
| 0 (Zero) | Short circuit of turns | Interturn short circuit | Replacement of relay |
| Normal (3-30 Ohm) | Integrity is present | Sticking contacts | Cleaning or replacement |
| Jumping numbers | Unstable contact | Oxidation or crack | Replacing the relay |
If the check showed that the relay is working, but the refrigerator still does not start, the problem may hide deeper. Perhaps the compressor itself is faulty (turn-to-turn short circuit of the motor windings) or the starting capacitor (if it is in the circuit). In such cases, diagnostics require more complex current measurements and insulation testing, which is best left to a professional.
It is also worth considering that in some modern inverter refrigerators the starting relay as a separate unit may not be present. There, the engine start is controlled by an electronic unit (inverter), which converts the current. Testing such systems with a conventional tester are not very informative and require special equipment.
Replacement and testing of system functionality
If diagnostics confirm a malfunction, you need to purchase a new analogue. Relays are selected strictly according to the model of the refrigerator or according to the markings of the old device (for example RKT, PTC). Installation of a new part is carried out in the reverse order of removal. Make sure that the relay is firmly seated on the compressor terminals and that the wires are connected according to the diagram.
After assembly, do not rush to close the back panel. Plug in the refrigerator and listen. A characteristic click should be heard, followed by the smooth hum of the operating compressor. If after 3-5 seconds there is no click, or the compressor hums but does not start, immediately turn off the device. This means that the problem is not in the relay, or the new relay is also defective.
In the first minutes of operation, the new compressor and relay may heat up slightly - this is normal. However, if the heat becomes excessive or sparks appear, the device must be de-energized again and the connection rechecked. An error in the polarity or order of connecting the wires can lead to combustion of the newly installed part.
Successful start-up and temperature rise in the refrigerator chambers indicate the completion of the repair. During the day, it is recommended to periodically check the operation of the unit, making sure that it does not turn off prematurely and freezes evenly.
Is it possible to repair an old relay by cleaning the contacts?
Theoretically, if the relay is collapsible and the contacts are simply burnt, they can be cleaned with fine sandpaper. However, such relays are rarely found in modern household refrigerators. Most of them are sealed in a plastic case. Opening it breaks the tightness and insulation, which makes operation dangerous. It’s easier and more reliable to buy a new part.
Why does a new relay burn out immediately after installation?
This may indicate a more serious problem with the compressor. If the motor “jams” or has an interturn short circuit, it consumes a starting current that exceeds the rated value. The relay tries to start the engine, overheats and burns out. In this case, replacing the relay is a temporary measure; a thorough repair of the motor is necessary.
How to distinguish a refrigerator relay from another type of relay?
Refrigerator relays are specific in terms of seating (distance between contacts) and orientation (vertical or horizontal fit on the compressor). There are no universal relays. When purchasing, it is important to pay attention to compatibility with your model of refrigerator or compressor (Danfoss, Secop, Embraco, etc.).