A sudden stop of the compressor or its hum without subsequent starting often indicates problems in the motor electrical circuit. Relay regulator, or the starting device, is a key element that ensures the motor starts and protects it from overloads. If this unit fails, the refrigerator stops producing cold, and food begins to deteriorate.
Independent testing of this component allows you to save on calling a technician and accurately determine the cause of the breakdown. In most cases, a malfunction can be diagnosed visually or using a simple tool, without having in-depth knowledge of electronics. Start relay This is an inexpensive part, the replacement of which often solves the problem of a “dead” refrigerator.
In this article we will analyze all aspects of diagnostics, from external signs to checking with a multimeter. You will learn how to safely remove the part, what to look for when inspecting the contacts, and how to understand that it is time to buy a new component.
The principle of operation and functions of the starting relay
The main task starting relay is to briefly connect the starting winding of the compressor motor. When the refrigerator is turned on, the motor rotor is stationary, and significant force is required to spin it up, which is provided by the additional winding. The relay supplies current to it only in the first seconds of operation, after which it turns off the circuit, and the engine continues to operate on the main winding.
The second critical function is thermal protection. Inside the device body there is often a bimetallic element that opens the circuit when overheating or excessive current flows. This prevents the motor windings from burning out when jammed or power surges. Thermal relay works autonomously and does not require external control.
There are two main types of such devices: electromagnetic and posistor. Electromagnetic models use current to move a core that closes contacts. Posistor, more modern, use the property of the material to sharply increase resistance when heated, actually breaking the circuit of the starting winding without mechanical movement.
- 🔌 Provides high voltage supply to the starting winding at the time of start.
- 🛡️ Protects the compressor from overheating and short circuit short circuit.
- ⏱️ Automatically turns off the starting circuit after the rotor spins up.
⚠️ Attention: Never try to start the compressor directly, bypassing the relay, even for a short time. This is guaranteed to lead to combustion of the motor windings.
External signs of device malfunction
It is possible to determine that relay regulator is faulty even before disassembling the unit. The most obvious symptom is a characteristic sound: the compressor tries to start, hums for a few seconds, then a click is heard and the motor stops. After some time, the cycle repeats. This sound is often described as “the refrigerator clicks and does not turn on.”
Another sign is a complete lack of response to being plugged in when the socket and light bulb inside the chamber are working. If the light is on but the engine is silent, the problem may lie in an open circuit inside the starter. It is also worth paying attention to the temperature of the relay housing: if it gets very hot or has melted, its performance is in doubt.
Sometimes a malfunction manifests itself in the form of spontaneous shutdowns of the refrigerator during operation. This may indicate that thermal protection it is triggering falsely or is too sensitive due to wear on the bimetallic strip. In such cases, the engine does not have time to reach operating mode.
If you notice a burning smell or visible traces of soot in the compressor area, this is an alarming signal. This suggests that the contacts inside the relay may have burned out, creating high contact resistance and heat. In such a situation, operating the equipment is dangerous.
Removing the relay for diagnostics
Before checking regulator relayit is necessary to ensure safety. Unplug the refrigerator and move it away from the wall. Access to the part is usually located at the lower rear of the unit where the compressor is located. Remove the protective cover, if any, and inspect the fastenings.
The relay is put directly on the contact group of the compressor. It is fixed with a bracket or plastic latches. Carefully remove the retaining bracket and pull the device down. It is important not to pull sharply so as not to damage the suitable wires. Contact group should remain on the compressor, and the relay should be in your hands.
After removal, carefully inspect the wires. If they are blackened or the insulation has melted, they will need to be cleaned or replaced before installing a new relay. Also check the contacts on the compressor itself - they should be clean and free of oxides.
☑️ Preparation for dismantling
Visual inspection and initial check
The first stage of diagnosis is a careful visual inspection. Shake the device near your ear. If a rattling sound is heard inside, similar to the rattling of coins, then the insides are destroyed. In electromagnetic relays this may mean a breakdown of the mechanism, and in posistor relays it can mean destruction of the ceramic element.
Inspect the housing for cracks, melting or traces of burning. If the plastic is blackened or deformed, starting relay definitely requires replacement. Also pay attention to the condition of the contacts inside: they should be smooth, without carbon deposits and shells.
For posistor relays, you can carry out a simple test: connect it to the network via a cord with a plug (being careful!). After a few seconds, the posistor should heat up and stop passing current (the resistance will increase). However, this method requires skills and is dangerous for beginners.
- 👁️ Look for cracks, chips and traces of thermal effects on the case.
- 🔊 Shake the device: extraneous noise inside is a sign of destruction.
- 🔥 A burning smell or visible carbon deposits on the contacts indicate breakdown.
⚠️ Attention: If traces of soot are visible inside the relay or a sharp smell of burnt plastic is felt, further checking with a multimeter may be pointless - the part must be disposed of.
Diagnostics with a multimeter: step-by-step instructions
The most accurate way how check relay regulator the refrigerator - use a multimeter in resistance measurement mode (Ohm). This method allows you to assess the integrity of the windings and the condition of the contacts. Switch the device to the 200 Ohm range or dialing mode.
For electromagnetic relays with a coil, measure the resistance between the coil contacts. It should be within normal limits (usually several tens or hundreds of ohms, the exact values depend on the model). If the device shows one (infinity), then there is a break in the coil and the relay will not create a magnetic field to start.
Check the contacts that close the starting winding. In the initial position (horizontally), they can be open or closed depending on the design. When the relay is turned 90 degrees (imitation of operation), the contacts should change their state. If there is no resistance anywhere or it is constantly infinitely large, the device is faulty.
For posistor relays, measure the resistance between the main contact and the starting winding contact. When cold it should be low (3-50 ohms). If the multimeter shows a break or, conversely, zero (short circuit), posistor burned out.
Nuances of checking an electromagnetic relay
In such relays, it is important to check not only the coil, but also the moving core. It should move freely inside the coil and have no signs of corrosion. If the core is soured, the relay may buzz, but not start the compressor.
Table of typical values and faults
For ease of diagnosis, below is a table with approximate values and symptoms of malfunctions for different types of devices. Remember that the exact parameters depend on the manufacturer and model of the compressor.
| Relay type | Normal resistance | Fault symptom | Probable cause |
|---|---|---|---|
| Posistor | 3–50 Ohm (cold) | Infinity or 0 Ohm | Destruction of the ceramic element |
| Electromagnetic | 10–100 Ohm (coil) | Open coil circuit | Burned coil winding |
| Thermal protection | 0 Ohm (closed) | Open circuit in a cold state | Deformation of the bimetallic plate |
| Contact group | 0 Ohm (closed) | High resistance | Soot, oxidation, burning |
If your measurements differ greatly from the tabulated ones, or the multimeter shows a break where the circuit should be, the part must be replaced. Do not try to repair the insides of the relay, as it is impossible to restore the tightness and calibration accuracy at home.
Replacement and selection of a new regulator relay
When buying a new part, it is critical to choose an analogue that is identical in characteristics. Relay regulator selected according to compressor power and type refrigerant. The body of an old device always has markings, for example, R-1, RTK-1-3, PTC, etc. Look for a device with exactly the same marking.
Installation is carried out in the reverse order. Push the new relay onto the compressor contact group until it stops. Ensure that the "UP" marking or arrow points upward if required by the design. Attach the fixing bracket and connect the wires according to the photograph taken earlier.
After assembly, plug in the refrigerator. The compressor should start with a characteristic sound, but without buzzing or clicking. After a few minutes, check if it starts to heat up (normal operating temperature) and listen to the operation: it should be smooth.
- 🛒 Buy a relay only with the same markings as on the old device.
- 📸 Be sure to photograph the wiring diagram before removing.
- 🧊 After replacing, let the refrigerator operate for several hours without loading.
⚠️ Attention: Technical specifications of compressors and requirements for starting devices may vary between different manufacturers. Always check the markings on the body of the part with supplier catalogs or instructions for your refrigerator model.
Frequently asked questions (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the motor by applying current directly to the starting winding, but do This is strictly prohibited in domestic conditions. This will cause the engine to quickly overheat and burn out, and also creates a risk of fire. A relay is an essential safety element.
Why does a new relay burn out after a short time?
If a new one starting relay fails quickly, the reason may be a malfunction of the compressor itself (interturn short circuit, jamming) or problems with the wiring in the house (voltage surges). It is also possible to install a relay with unsuitable power parameters.
What is the difference between the RTK relay and the PTC?
RTK is an electromagnetic relay with a coil and a movable core (old style). PTC (posistor) is a modern device without moving parts that works based on changes in the resistance of the crystal when heated. They are not always interchangeable without changing the connection diagram.
How can you understand that the problem is in the relay and not in the compressor?
If you hear a click from the relay when you turn it on, but the compressor does not start and hums, and when power is applied directly (which the master should do), the motor starts, the problem is in the relay. If the motor hums even with a direct connection or knocks out the machines, the problem is in the compressor.