A sudden stop in the operation of refrigeration equipment often takes you by surprise, especially when there are perishable products inside. One of the most common causes of such a malfunction is the failure of start relay, which is responsible for starting the compressor electric motor. If you hear a characteristic click, but the engine does not start, or the compressor hums, but does not pick up speed, there is a high probability that the problem lies in this small but critically important unit.
Independent relay replacement is a procedure accessible even to non-professionals, if you follow safety precautions and a clear algorithm of actions. Unlike complex repairs that require evacuating the system, there is no need to open the circuit or handle the refrigerant. However, it is important to understand that any work with electrical appliances requires caution, since the voltage in the network can be life-threatening.
In this guide we will look in detail at how to correctly diagnose a breakdown, select the appropriate spare part and install a new element. Following all the steps will allow you to save on the services of a technician and bring the equipment back to life as soon as possible. Remember that a competent approach to repairs extends the service life service of your refrigerator.
Diagnostics of a malfunction of the starting relay
Before you begin dismantling and installing new parts, you need to make sure that the problem lies in the relay. Often the symptoms of a malfunction of this unit are confused with a breakdown of the compressor or thermostat itself. The main symptom is when the refrigerator turns on, there is a click, the motor hums for a couple of seconds and turns off again with a characteristic sound.
For the initial check, it is not necessary to immediately disassemble the unit. Pay attention to the frequency at which the compressor turns on. If it tries to start every few minutes but doesn't cool down, that's a good sign to check further. It is also worth listening: if the humming is accompanied by strong heating of the motor housing, this may indicate that starting winding does not turn off in time.
- 🔊 A characteristic click when trying to start, followed by silence.
- 🔥 Strong heating of the compressor when the fan is running (if there is one).
- ❌ Refusal of the refrigeration chamber to gain temperature when the light is on.
- ⚡ Knocking out plugs or circuit breakers in the electrical panel at the time of startup.
⚠️ Attention: If after several attempts to start the compressor housing becomes scalding hot, immediately unplug the appliance. Long-term operation in this mode can lead to an interturn short circuit and complete combustion of the engine.
Necessary tools and safety measures
Installing a relay on a refrigerator does not require complex professional equipment, but a basic set of tools must be prepared. The main condition before starting any work is to completely disconnect the device from the electrical network. Even if you simply remove the back cover, there is still a risk of electric shock if the cord is in an outlet.
You will need a standard screwdriver, a multimeter to test the continuity of the circuit, and possibly pliers. If the contacts on the old relay are badly burned or oxidized, you may need to use fine sandpaper to clean the terminals, although this is rarely done when installing a new part. It is important to ensure good lighting of the working area, since the compressor niche is often dark and cramped.
Do not forget to prepare a container to collect possible condensation or oil that may drip when removing the casing. Although there is no oil in the relay itself, it may be present in the tubes or at the bottom of the compressor. Protective gloves will help avoid cuts on the sharp edges of the metal casing.
☑️ Preparation for repair
Removing the old relay and visual inspection
The dismantling process begins with removing the protective cover covering the compressor. It is usually secured with bolts or snaps. After removing the cover, you will see the compressor itself, which has a smaller plastic casing attached to the bottom or side. It is in this that the desired starting device is located Carefully remove the plastic box. Inside you will see a relay mounted on the compressor rod and wires suitable for it. Before pulling the parts, it is recommended to take a photo of the connection diagram so that when installing a new element you do not get confused in the color marking of the wires. This is especially important for models with multiple contacts..
Carefully remove the plastic box. Inside you will see a relay mounted on the compressor rod and wires suitable for it. Before pulling the parts, it is recommended to take a photo of the connection diagram so that when installing a new element you do not get confused in the color marking of the wires. This is especially important for models with multiple contacts.
Remove the terminals from the relay contacts. They may fit tightly, so be careful not to damage the wiring. After disconnecting the wires, the relay is easily removed from the compressor rod. Visually inspect the removed part: the presence of traces of burning, melting of plastic or a characteristic burning smell confirms the need for replacement.
What is inside the plastic relay housing?
Inside the start relay there is an inductor and a moving contact. When voltage is applied, the coil creates a magnetic field that draws in the core and closes the contacts, supplying current to the motor's starting winding. As soon as the rotor picks up speed, the current drops, the magnetic field weakens, and the contacts open. If this mechanism jams or burns out, starting becomes impossible.
Selecting an analogue and checking a new component
Relays for refrigerators are not universal. They are selected strictly according to the power and type of compressor. There is always a marking on the body of the part, for example, RTK-X, LS-07B or 17.5 μF. These designations are critical when looking for a replacement. Using an unsuitable relay can lead to repeated breakdown or damage to the motor windings.
If you buy a new relay, compare its appearance and contact arrangement with the old model. Note the orientation of the arrow on the housing: it should point down toward the ground when the relay is installed on the compressor. This requirement is related to the operating principle of mechanical relays, where gravity helps to open the contacts.
Before installation, it is advisable to “ring” the new relay with a multimeter to exclude manufacturing defects. In the normal state (rod up) the circuit should be open. If the multimeter shows a short circuit immediately, or vice versa - infinite resistance where it should not be, the part is faulty.
| Parameter | Description | Importance |
|---|---|---|
| Power | Must match the power compressor (usually 1/4 - 1/3 hp) | High |
| Orientation | The arrow on the housing should point down during installation | Critical |
| Type contacts | The number and location of pins must match | High |
| Voltage | Standard 220V, but there is also one for 110V (rarely) | Average |
Technology for installing a relay on a compressor
The process of installing a new element is technically simple, but requires care. Take the new relay and place it on the three contact pins protruding from the compressor housing. The movement should be confident, but without excessive effort. You should feel that the part is firmly in place.
The key point is the correct orientation. There is an arrow or inscription on the relay body UP/TOP. In the operating position, this marking should be on top, and the opposite end, where there is often a hole or protrusion, should look straight down. Incorrect orientation will result in the contacts not opening and the compressor will burn out.
After mechanical installation, connect the wires to the contact terminals. Follow the pattern you photographed earlier, or use colors as a guide if they haven't been changed in previous renovations. The terminals should snap into place with a slight click. Make sure that the wires do not touch hot parts of the compressor or sharp edges of the casing.
⚠️ Attention: Never install a relay if the compressor pins have signs of oxidation or carbon deposits. Clean them with fine sandpaper before installation, otherwise the contact will be poor, which will cause sparking and repeated failure.
First start-up and performance check
After all connections are made, you can begin testing. Do not rush to close the back cover immediately. Plug in the refrigerator and listen carefully. After a few seconds the relay should click and the compressor will start. If the startup was smooth, without buzzing or repeated clicks, then the installation was successful.
Check the compressor heating in the first 10-15 minutes of operation. It should heat evenly, but not be hot. It is also worth measuring the current consumption, if possible, to make sure that it is within the rating indicated on the motor nameplate.
- ✅ The compressor started the first time without buzzing.
- ✅ The relay does not make any extraneous sounds (cracking, buzzing).
- ✅ The refrigerator began to gain temperature in the chambers.
- ✅ The relay body remains cold or slightly warm.
Frequent installation errors and their consequences
One of the most common mistakes is ignoring the orientation of the relay. As mentioned earlier, mechanical devices are dependent on gravity. If you install the relay upside down, the moving contact may stick in the closed state, which will lead to continuous operation of the starting winding and its burnout.
Another error is poor contact in the terminals. If the wire is not inserted all the way or the terminal is loose, high contact resistance will occur at the connection. This will cause local heating, melting of the plastic and possible fire. Always check that the wires are securely fastened.
It is also considered a mistake to install a higher power relay “just in case”. This may result in the contacts not opening in time, since the current in the operating winding will be insufficient to demagnetize the relay coil. Use only those ratings recommended by the manufacturer.
⚠️ Attention: Characteristics of electric motors and requirements for starting fittings may vary depending on the production series. Always check the markings on a new part with the data on the nameplate of your specific compressor, and not just with the model of the refrigerator.
FAQ: Frequently asked questions
Is it possible to install a relay from another refrigerator?
Yes, you can, but only if the electrical parameters (power, type of compressor) and geometric dimensions of the seat. The brand of the refrigerator is secondary, the main thing is the engine model.
Why does the new relay click, but the compressor does not start?
This may indicate a malfunction of the compressor itself (jamming, broken windings) or that a relay with inappropriate characteristics has been selected. It is also worth checking the capacitor if it is present in the circuit.
How long does the starting relay last?
The average service life is 5-10 years, but it greatly depends on the number of on/off cycles and the stability of the voltage in the network. Frequent voltage surges reduce the service life of the part.
Do you need to change the capacitor together with the relay?
If your model has a starting capacitor, it is recommended to check it or replace it preventively, since it works in tandem with the relay and ages at about the same time.
Is it dangerous to change it yourself relay?
The procedure is safe if you completely disconnect the device from the network. However, if you are not confident in your abilities or see damaged wiring, it is better to contact a professional technician.