Sudden stop compressor or loud clicks when trying to start the refrigerator often indicate a failure of the start relay. This small but critical element is responsible for starting the electric motor and protecting against overloads. If you are faced with the fact that the unit hums, but does not turn on, or, conversely, turns off immediately, most likely the problem lies in this particular unit.
Fortunately, replacing the start relay is one of the most accessible procedures in self-repair of household appliances. You will not need it sophisticated tools or deep knowledge of electrical engineering to cope with the task in 20–30 minutes. The main thing is to follow safety precautions and choose the right spare part that matches the model of your compressor.
In this article we will analyze in detail the process of diagnosing, selecting and installing a new component. You will learn how to determine that the relay has really burned out, what types of these devices exist and what to pay attention to during installation so that the refrigerator works like new again.
Fault diagnosis: signs of failure
Before disassembling the back wall of the refrigerator, you need to make sure that the problem is in the start relay. Often the symptoms can be similar to a malfunction of the compressor or thermostat itself. The main sign is a characteristic sound: you hear the motor trying to start, there is a loud click, followed by silence or the cycle repeats after a while.
If during operation you hear a crackling or buzzing noise that ends abruptly, this is a sure signal that starting winding is not receiving the necessary impulse. It is also worth paying attention to the temperature of the compressor: if it is hot, but the refrigerator inside is warm, it means that the circulation of the refrigerant is impaired due to the engine stopping. In some cases, the circuit breaker in the apartment's electrical panel may be knocked out.
⚠️ Attention: If, after clicking the relay, the compressor continues to hum for more than 5-7 seconds and does not start, immediately disconnect the device from the network. Long-term operation in this mode can lead to burnout of the motor windings, and then repairs will cost much more.
For a final visual check of the relay, it must be removed. In good condition, there should be no burning, melted contacts or foreign odors inside the case. If the relay makes a rattling sound when shaken, this indicates destruction of the internal mechanism or core, which requires mandatory replacement.
Necessary tools and preparation
The replacement process does not require professional equipment, but having a certain set of tools will greatly simplify the task and ensure safety. You don't need to buy expensive equipment; a basic DIY kit is enough. It is important that all tools are dry and in good working order.
For work you will need:
- 🔧 Screwdrivers (phillips and flat) for removing protective panels.
- 🔦 Flashlight for illuminating the working area in the compressor niche.
- 🧤 Dielectric gloves for protection against residual current.
- 📷 Smartphone or camera to photograph the connection diagram before removal.
Before starting any work, be sure to disconnect the refrigerator from the power supply. Safety is priority number one. Even if you plan to simply test the contacts, the risk of electric shock while the cord is plugged in is too great. It is also recommended to move the unit away from the wall, providing free access to the rear.
If there is dust or cobwebs on the back wall, it is better to carefully remove them with a dry cloth before disassembling. It is unacceptable for debris to enter the electrical part of the compressor. Make sure that the floor under the refrigerator is dry to prevent heavy structural elements from slipping and falling.
Removing the old start relay
After turning off the power and moving the refrigerator away, you can begin to remove the protective casing. It is usually secured with latches or screws at the bottom of the back wall. Be careful, the plastic becomes brittle over time, and sudden movement can lead to breakage of the fasteners.
Removing the casing, you will see the compressor - a black metal “tank” with tubes. The desired device is located on its side or bottom (depending on the model). It is put directly on the compressor rod and connected to the wires. Before removal, be sure to take a photo of the connection so that when installing a new relay you do not mix up the contacts.
The dismantling process is as follows:
- 📸 Take a photo of the location of the wires and terminals.
- 🔌 Carefully disconnect the wire connectors from the relay contacts.
- 🔩 Remove the retaining bracket or spring, if any.
- 👐 Remove the relay from the compressor rod by gently rocking it.
⚠️ Attention: Do not use excessive force when removing the relay from the rod. If it gets stuck, gently twist it from side to side. A sharp jerk can damage the compressor leads, which will lead to a freon leak and the need to call a technician with soldering equipment.
After removing the device, inspect it. Often you can see traces of burning or melted plastic on the inside of the lid. This confirms that the part has failed. Now you need to select an analogue for replacement.
Selection and compatibility of a new relay
Start relays come in different types: posistor, inductive, with or without additional protection. For household refrigerators, posistor models are most often used, which are universal and reliable. However, it is important to choose a device that matches the power of your compressor.
When choosing, pay attention to the markings. Numbers and letters on the case indicate the series and technical characteristics. For example, marking PTC indicates the presence of a posistor. If you are not sure of compatibility, it is better to take the old relay with you to the store or find its article number on the Internet according to the refrigerator model.
Below is a table of correspondence between relay types and their characteristics:
| Relay type | Operation principle | Application | Features |
|---|---|---|---|
| Posistor (PTC) | Crystal heating | Modern refrigerators | Universal, cheap |
| Induction | Electromagnetic field | Old models (USSR) | Position sensitive |
| Thermal | Bimetallic plate | Combined systems | Overheat protection |
| Relay with capacitor | Phase shift | Powerful compressors | Requires precise selection |
If you buy a universal relay, the kit often includes adapters for different types of compressor pins. Carefully read the instructions for the new device. Critically importantso that the relay contacts sit tightly on the compressor terminals; backlash is unacceptable, as it will cause sparking and repeated breakdown.
Is it possible to install a relay of higher power?
Theoretically, it is possible if it physically fits the seats. However, it is strictly forbidden to install a lower power relay - it will burn out instantly. It is best to look for an exact analogue by catalog number.
Step-by-step installation and connection
Installation of a new starting relay is carried out in the reverse order of dismantling. Make sure the new device is oriented correctly: there is usually a UP or TOPmark on the case indicating the top position. Incorrect orientation can lead to incorrect operation of the mechanism.
Place the relay onto the compressor rod until it clicks or is firmly seated. Then connect the wires to the terminals according to the photo taken earlier. Make sure the connectors snap into place and are not loose. If the kit comes with new terminals or wires, replace the old ones if they look oxidized.
Checklist for correct installation:
- ✅ The relay is placed on the rod tightly and without distortions.
- ✅ The top marking (
TOP) looks up. - ✅ Wires connected to the correct contacts (R, S, C).
- ✅ The compressor protective cover is in place.
After connecting the wires, replace the compressor protective cover and screw it on. Make sure that the refrigerant pipes are not pinched or touching any sharp metal edges. Only after complete assembly can you turn on the refrigerator to the network.
☑️ Final check before turning on
First start and operation check
Plug in the refrigerator. In the first seconds, you can hear the characteristic click of the relay and then the smooth hum of the operating compressor. This is a good sign. Allow the unit to operate for 10-15 minutes without load (without food) to ensure stable operation.
Check whether the new relay is overheating. Slight heat is normal, but should not burn your hand. Also listen to the sounds: there should be no knocking, rattling or intermittent humming. If the compressor is running smoothly, you can close access to the rear wall.
If the refrigerator does not start or knocks out the plugs again:
- 🛑 Immediately turn off the device.
- 🔍 Check that the wires are connected correctly.
- 🔎 Make sure that the relay matches the compressor model.
- 📞 Perhaps the problem is deeper (compressor or wiring malfunction).
⚠️ Attention: If after replacing the relay the compressor hums, but does not start, and at the same time gets very hot, the motor-compressor itself may be jammed. In this case, replacing the relay will not help; professional diagnostics or replacement of the compressor will be required.
Successful startup and stable operation means that you have successfully completed the repair. Now the refrigerator will cool the food again, and you have saved a significant amount on calling a technician.
Frequently asked questions (FAQ)
Is it possible repair an old relay if it is burned out?
Theoretically, some craftsmen open the case, clean the contacts or change the posistor. However, this is a temporary solution. The calibration inside has already been broken, and a second breakdown will happen quickly. It is safer and more reliable to buy a new relay, which is inexpensive.
Why did the relay burn out? What is the reason?
The main reasons: power surges in the network, frequent on-off switching (short-term), overheating of the compressor due to contamination of the condenser at the back, or a malfunction of the thermostat, causing the motor to work without interruption.
Is a universal relay suitable for any refrigerator?
Universal relays are suitable for most modern compressors with a power up to a certain value (usually up to 1000 W). The main thing is to check the compliance of the connectors and the type of compressor (R600a or R134a), although for the relay itself the type of freon is not important, the power is important.
Is it dangerous to change the relay yourself?
The replacement process is safe if you follow the rule: all work only when the device is disconnected from the network. The only risk is damage to the compressor tubes due to careless handling, which will lead to gas leakage. Proceed with caution.