A sudden stop of the compressor is always stressful for the owner of household appliances, because food supplies are at risk. Most often, the reason for this behavior is not a breakdown of the motor itself, but a failure start relay. This small but critical element is responsible for starting the engine and protecting it from overloads. If the refrigerator hums but does not start, or, conversely, turns on and immediately clicks, turning off after a few seconds, then the likelihood of a malfunction in this particular unit is extremely high.
Diagnostics of this component does not always require calling a technician, since many operations can be performed independently with basic tools. Start relay is a plastic box attached to the compressor housing, inside which there is an electrical circuit with a coil and contacts. Understanding the principle of its operation will help you not only save on repairs, but also correctly diagnose the problem, eliminating more serious breakdowns.
Before proceeding with disassembly, you must completely de-energize the unit. High residual voltage may remain inside the compressor, so even after disconnecting from the network, it is not recommended to touch the contacts with bare hands. In this article we will analyze all stages of the test: from visual inspection to dialing multimeter, and also consider typical symptoms indicating the need to replace the part.
Typical symptoms of a faulty starting relay
Determine that the problem lies in the starting relay mechanism, it is possible by the characteristic sounds and behavior of the refrigeration chamber. Often, owners notice that the unit stops freezing, although the light inside is on. The compressor may try to start, making a loud clicking noise, but immediately stall. This is a classic sign that starting winding does not receive the required impulse or the thermal protection is triggered.
Another alarming signal is cyclical operation. The engine starts, runs for a few seconds, then there is a clicking sound and there is silence. After some time, the cycle repeats. In such situations, sticking contacts or a burnt-out coil inside the relay is often to blame. There may also be strong heating of the compressor housing in the lower part, which indicates that the motor is trying to start without success.
- 🔊 A loud click when trying to start, followed by silence.
- ❄️ Lack of cold in the chambers when the backlight and fans are running.
- 🔥 Strong heating of the compressor housing (more than 60-70 degrees).
- ⚡ Triggering of circuit breakers in the electrical panel when the refrigerator is turned on.
It is important to distinguish these symptoms from problems with the thermostat or freon leak. If the engine hums smoothly and for a long time, but there is no cold, most likely the problem is not in the relay. However, if the startup does not occur at all or occurs in jerks, then start-up protection device is the first candidate for verification. Ignoring these signs can lead to burnout of the windings of the compressor itself, which will make repairs economically unfeasible.
⚠️ Attention: If you smell burning or see melted plastic on the relay body, further operation of the refrigerator without replacing the part is strictly prohibited. This can lead to a short circuit in the apartment's wiring.
The frequency of occurrence of such problems depends on the quality of electricity in the network and operating conditions. Voltage surges often cause the failure of sensitive electronics and trigger mechanisms. Therefore, if the light in your house often “flashes”, it makes sense to think about installing a voltage stabilizer to protect equipment.
Removing the relay: preparation and procedure
To carry out high-quality diagnostics, it is necessary to remove the part from the refrigerator body. This process is not very complicated, but requires care and compliance with safety measures. First, move the unit away from the wall to gain access to the rear panel. Make sure that the power cord is unplugged from the outlet - this is a prerequisite for any work with electrical appliances.
On the back wall, at the bottom, you will see a compressor - a black cylindrical metal tank. A plastic box is attached to the side or bottom, often covered with an additional casing. This is where the element you are looking for is located. In some models, for example Indesit or Atlant, access may be limited by the design features of the case, requiring removal of the rear panel completely.
☑️ Preparation for dismantling
The removal process usually looks like this: first, the fixing bracket or spring is removed a clamp holding a plastic cup. Then the wires going to the contact group are carefully disconnected. It is recommended to take a photograph of the connection diagram before disconnecting it, so as not to confuse the contacts during assembly. After this, the relay is simply pulled off the three pins of the compressor.
Pay attention to the condition of the external contacts and wires. If you notice traces of oxidation, blackening or melting of the insulation, this indicates overheating. Contact group should be clean and free of carbon deposits. Any visible defects in the relay body, such as cracks or swelling, are a direct indication that the part requires replacement, even if an internal check shows conditional serviceability.
Visual inspection and primary diagnostics
After removing the device from the seat, you can begin a more detailed study. Shake the relay next to your ear: if you hear a ringing or knocking sound inside, it means the contacts have become loose or fallen off, and the device is definitely faulty. In good condition, there should be no extraneous sounds inside when shaking.
Carefully inspect the insides through the openings of the case. In some models, especially with posistor starting, you can see a ceramic element. If cracks or traces of burning are visible on it, this is a sure sign of a breakdown. For relays with a contact system, the condition of the reed and coil is important. Carbon deposits on the contacts can prevent the normal closure of the circuit, which is why the phase is not supplied to the starting winding.
- 👀 The presence of black carbon deposits on the contacts indicates sparking.
- 🧱 Cracks on the posistor body indicate thermal breakdown.
- 🔌 Melting of the plastic case indicates an excess current load.
- 🤐 Sticking of the moving parts of the trigger mechanism.
Some types of relays, for example RTK or R-1, have a collapsible housing, which allows you to look inside. Others, such as modern analogues for Bosch or LG, are often soldered or glued, and their verification is possible only by instrumental methods. If no visual defects are found, we proceed to the use of measuring instruments.
⚠️ Attention: Do not try to clean the contacts with sandpaper or a needle file in the hope of extending the life of the relay. This is a temporary measure that violates the factory coating and after a short time will lead to a repeated, more serious failure.
Checking with a multimeter: step-by-step instructions
The most accurate result is obtained by checking with a multimeter (tester). This device will allow you to measure the resistance of the coils and check the integrity of the circuit. Switch the multimeter to resistance measurement mode (ohms) to the 200 ohms limit. First, check the integrity of the coil: the probes are applied to the corresponding contacts. The device should show a certain value, usually in the range from 30 to 200 Ohms, depending on the model.
If one or infinity is displayed on the screen, then there is a break in the coil and the relay must be replaced. It is also necessary to check the thermal relay (bimetallic strip). In a cold state, the contacts must be closed, that is, the device must show zero or a value close to it. If the circuit is open to cold, the protection will not allow the compressor to start.
To check the posistor (if it is in the design), measure the resistance between its terminals. It should be several tens of ohms. The main feature of a posistor is that when heated, its resistance increases sharply, opening the starting winding circuit. It is difficult to check this dynamic process at home, so they often rely on static resistance and appearance.
How to test a relay without a multimeter?
There is a risky method of checking by applying 220V voltage directly, bypassing the relay, but only for a short-term start. This requires special skills and is life-threatening. If you are not an electrician, do not use this method, as you can burn the compressor windings or get an electric shock.
It is also important to ring the contacts responsible for supplying power to the main winding. They should ring short (resistance close to 0 Ohm). If high resistance is detected here, then the contact is broken and sufficient current will not flow to the motor. It is better to carry out all measurements while holding the relay in your hands, not connected to the compressor.
Comparison of relay types and their characteristics
Modern and old refrigerators use different types of starting devices. Understanding the difference between them helps you find the problem faster. Induction relays operate due to an electromagnetic coil, which closes the contacts when starting, and opens them when the speed increases. PTC systems use the property of the material to change resistance when heated by current.
PTISTOR systems are considered more reliable and simpler, since they have no moving mechanical parts that could wear out. However, they are sensitive to voltage surges. Induction relays (for example, series RTP) have a mechanical anchor, which over time can stick or lose the elasticity of the spring.
| Relay type | Principle of operation | Typical fault | Resource |
|---|---|---|---|
| Posistor | Change in resistance when heated | Crack of a ceramic element | High |
| Induction (RTK) | Electromagnetic coil and armature | Contact sticking, coil breakage | Medium |
| Thermal | Bimetal plate | Loss of elasticity, contact burning | Low |
| Combined | Combination starting and thermal | Complex failure | Depends on the model |
When selecting a replacement, it is important to take into account not only the appearance, but also the marking. Rated current and the type of refrigerant can also matter, although for most household models there are universal analogues. If you are changing an induction relay to a posistor relay (or vice versa), make sure that the connection diagram allows this, since the design of the contacts may differ.
Replacement of the part and final assembly
If the diagnostics confirmed a malfunction, the relay must be replaced. A new part can be purchased at home appliance spare parts stores by naming the model of the refrigerator or showing the markings of the old device. Installation is carried out in the reverse order of removal. Insert the relay onto the three pins of the compressor until it stops, observing the orientation (usually with the lettering up).
Connect the wires to the terminal block according to the photograph or diagram taken earlier. Make sure the connectors are tight and not loose. Attach the retaining bracket or spring. After assembly, do not rush to immediately plug in the refrigerator - let the device stand for 15-20 minutes, especially if you kept it upside down for a long time.
First start after replacement - critical moment. Turn on the refrigerator and listen. The engine should start with a characteristic hum, without unnecessary clicks or buzzing that lasts more than 3-5 seconds. If the start-up was successful, the compressor will pick up speed and go into cooling mode. After 10-15 minutes, check whether the condenser grilles on the sides of the unit have begun to heat up.
⚠️ Attention: If after replacing the relay the refrigerator does not start again or knocks out plugs, the problem may be deeper - perhaps the compressor itself is faulty or there is a short circuit in the wiring. In this case, further repairs with your own hands are dangerous.
Frequently asked questions (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Technically, you can start the motor by applying voltage directly to the working and starting windings, but this can only be done for a few seconds for diagnostics. Long-term operation without a relay will lead to burnout of the windings, since the protection against overheating and shutdown of the starting circuit will not work.
Why does a new relay burn out after a week?
A common reason is an incorrectly selected rated current or type of relay. Also, the reason may be “difficult” starting of the compressor due to worn-out bearings or problems with freon, which creates an increased load on the starting system.
Where can I find the relay markings?
The marking is usually applied to the side or top edge of the plastic case. Look for inscriptions like RTK-1, 17.5M or manufacturer codes like Danfoss, Secop. If the inscription is erased, look for an analogue by the photo and the number of contacts.
Do I need to change the thermal relay if I change the starting one?
In most modern combined devices they are a single block, and change together. If you have a separate system and only the starting one burned out, the thermal one can be left, but only after checking its resistance with a tester.
Is it dangerous to change the relay yourself?
If you follow the electrical safety rules (disconnecting from the network), the risk is minimal. The main danger is electric shock when the device is turned on or damage to the wire insulation due to careless assembly. If you are not confident in your abilities, it is better to entrust the work to a professional.