A sudden stop of the compressor or its chaotic turning on and off often signals a failure of the starting device. It is this small unit that is responsible for starting the engine of the refrigeration unit and protecting its windings from overheating. Understanding how to replace a relay on a refrigerator can save your equipment from expensive repairs in a service center or a complete replacement of the compressor.
In most cases, failure occurs due to wear of the contacts, burnout of the bimetallic plate, or destruction of the housing. If you hear clicks, but the engine does not start, or, conversely, the hum stops a few seconds after turning on, the problem most likely lies in the trigger mechanism. Self-replacement is possible if you have basic skills in working with tools and strictly adhere to safety precautions.
Before starting disassembly, it is necessary to completely turn off the power to the household appliance. Unplug the cord from the outlet to reduce the risk of electric shock. Move the refrigerator away from the wall, allowing access to the rear of the unit where the compressor is located. Only after completing these steps can you begin to diagnose and dismantle the faulty part.
Diagnostics of a faulty starting device
The first step in the repair process is to accurately determine the cause of the breakdown. Often, symptoms indicating a faulty relay can be confused with problems with the compressor or thermostat itself. Start relay is an electromechanical switch that supplies current to the starting winding of the engine only at the moment of starting. If this process is disrupted, the motor either hums but does not spin, or makes a loud click and goes silent.
For an initial check, you can use the method of visual inspection and listening. If, when plugged in, there is a loud click followed by silence and the compressor does not start, this is a sure sign that the mechanism cannot complete the circuit. Sometimes the cause is sticking contacts or destruction of the internal inductor. In some models, such as Indesit or Atlant, the malfunction is accompanied by a characteristic cracking noise.
A more accurate diagnosis can be made by removing the protective casing and disconnecting the part from the compressor. Gently shake the device near your ear: if a rattling sound is heard inside, it means that the bimetallic strip or core has lost its integrity. Also inspect the contacts for carbon deposits or melting. If there are no visual defects, you will need a multimeter to check the resistance of the windings.
⚠️ Attention: If after replacing the relay the compressor continues to hum and does not start, the problem may be a jammed piston group or an interturn short circuit. Further attempts to turn on may lead to burning of the motor windings.
It is important to distinguish a relay failure from a thermostat failure. If the compressor is silent and does not make any sounds when turned on, check the thermostat circuit. However, if the motor tries to start, but immediately stalls, the focus should be on the starting device and the capacitor.
Necessary tools and preparation for work
Replacing the relay on the refrigerator does not require complex professional equipment, but having the right tools will significantly speed up the process and ensure safety. You will need a standard DIY kit, which is found in the garage of many equipment owners. The main thing is to act carefully so as not to damage the refrigeration circuit tubes.
To perform the work, prepare the following list of tools:
- 🔧 Screwdrivers (Phillips and flat) for removing the casing and terminals.
- 🧤 Dielectric gloves for protection against residual voltage.
- 🧹 A brush with stiff bristles for cleaning contacts from dust and oxides.
- 📱 A smartphone for photographing the connection diagram before disassembling.
- 🧲 A magnet or container for collecting small screws and parts.
Pay special attention to the cleanliness of the working places. Dust and dirt trapped inside the compressor or on the contacts of the new relay can cause a short circuit. Before starting work, it is recommended to wipe the area around the compressor with a dry cloth. If you are working with Bosch or LGmodels, make sure there is enough room to maneuver around as the rear wall layout can be tight.
Selecting the right new part is critical. Relays come in different types: posistor (for models with one contact) and induction (with two contacts). Marking on the case must match the original or be on the list of compatible analogues. An incorrectly selected device may not start the compressor or burn out in the first seconds of operation.
Removing the old start relay
The process of removing the faulty part begins with dismantling the protective plastic casing covering the compressor. It is usually secured with latches or bolts. Be careful: plastic can become brittle and brittle after years of use. Carefully bend the fasteners, being careful not to use excessive force so as not to break the fasteners.
After removing the casing, you will see a compressor with a starting device attached to the bottom or side of it. It can be closed with an additional metal bracket or a plastic retainer. Loosen the fasteners and remove the retaining frame. Now the relay is free, but still connected to the electrical circuit.
Carefully disconnect the wires going to the contact group. In some cases, for example, in refrigerators Stinol or Biryusa, the wires may be tightly clamped in the terminals. Use pliers with insulated handles to avoid damaging the wire insulation. Do not pull on the wires themselves - hold on to the terminal body.
Remove the relay from the compressor pins. It simply fits onto three contacts (or two, depending on the model). The movement should be directed strictly downward or to the side, without distortion, so as not to bend the contact pins on the compressor itself. If the relay is “stuck” due to temperature, gently rock it from side to side.
☑️ Removal procedure
Types of relays and their design features
Understanding the differences between the types of starting devices helps not only in choosing a replacement, but also in understanding the operating principle of your refrigerator. There are two main types of devices, which differ radically in their internal structure and operating principle. An error in choosing the type will lead to the system not working.
The first type is induction relay. It operates on the basis of an electromagnetic coil and a movable core. When voltage is applied, current passes through the winding, creating a magnetic field that draws in the core and closes the contacts of the starting winding. As the motor rotor picks up speed, the current drops and the core, under the influence of gravity (or a spring), opens the circuit. Such devices are often marked RTP, R-1 and are installed vertically.
The second type is positor (thermal) relay. It is based on a ceramic element (posistor), which sharply increases its resistance when heated. When the refrigerator is turned on, current flows through the posistor, starting the engine. When heated, the resistance increases, the current practically stops, and the starting winding is turned off. Such relays, often labeled as RE, are more compact and less sensitive to position, but require time to cool down (3-5 minutes) before restarting.
| Characteristics | Induction (RTP, R-1) | Posistor (resistance protection, PZK) |
|---|---|---|
| Principle of operation | Electromagnetic | Thermal (posistor) |
| Sensitivity to position | High (vertical only) | Low (universal) |
| Cooling time | Instant or fast | 3-5 minutes |
| Typical brands | Atlant, Stinol, old Indesit | Modern LG, Samsung, Bosch |
When choosing a replacement, be sure to pay attention to the number of contacts and their location. Even if the relay type is the same, the geometry of the seat may differ. Universal models sometimes require modification of the terminals or the use of adapters, which is not always reliable in vibration conditions.
Installation of a new relay and assembly of the system
Installation of a new part is carried out in the reverse order of dismantling. First make sure the compressor pins are clean and free of oxides. If necessary, gently sand them down with fine sandpaper or an eraser. Slide the new relay onto the contacts as far as it will go. It should fit tightly and not wobble.
Next, connect the wires to the appropriate terminals. Correct polarity and circuit matching is critical here. By mixing up the wires, you can cause a short circuit or damage the compressor windings. Use a photo you took earlier for reference. If the wires are color-coded, connect red to red, white to white, and so on, but it is better to double-check using the diagram on the case.
Secure the device with a mounting bracket or frame. Make sure that the wires do not touch hot parts of the compressor or sharp metal edges that could chafe the insulation during vibration. For additional protection, you can use heat-resistant electrical tape or plastic clamps.
What to do if the new relay does not fit in size?
If the purchased relay is slightly different in size, but has similar electrical characteristics and mounting holes, it can be installed by carefully straightening the wires. However, if the landing pins do not match, it is strictly not recommended to use adapters or bend the contacts - this will break the electrical contact. In this case, it is better to order the exact model using the catalog number.
After mechanical installation, return the compressor protective casing to its place and secure it. Make sure all screws are tight and the plastic latches are closed. Now you can begin a test run of the unit.
Checking functionality and typical errors
The final stage is connecting the refrigerator to the network. In the first seconds, listen carefully to the operation of the compressor. It should start smoothly, without buzzing or extraneous vibrations. If you can hear the confident hum of a running motor, it means the replacement was successful. Let the refrigerator run for 10-15 minutes to make sure the cycle is stable.
One of the common mistakes is ignoring the compressor cooling time. If you tried to start the refrigerator several times during diagnostics, let it stand turned off for at least 30-40 minutes. An attempt to start a hot compressor with a new relay can lead to instant failure of the new part due to high freon pressure in the system.
Users also often forget to check the integrity of the wires. If the insulation of the wire leading to the relay is damaged and touches the metal housing, the protection may trip or current may leak. Carefully inspect the entire wiring harness for cracks and melts.
⚠️ Attention: If after replacing the relay the refrigerator begins to freeze, but the compressor does not turn off, check the thermostat. Perhaps the problem was complex, or the new relay was selected with incorrect shutdown current parameters.
Another mistake is using a relay from a different type of compressor. For example, installing a relay from a single-phase motor to a two-phase one (or vice versa) will lead to incorrect operation of the starting winding. Always check the markings and specifications.
Frequently asked questions (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start a compressor without a starting device by applying voltage directly to the starting winding, but do this in in domestic conditions is extremely dangerous and is not recommended. This requires precise timing of the pulse (fractions of a second). Incorrect actions will lead to burnout of the windings or fire. Use this method only for diagnostics in extreme cases.
Why does a new relay burn out after a few days?
A common reason is unstable voltage in the network or problems with the compressor itself (difficult starting, bearing wear). It is also possible that a relay with an inappropriate operating current has been selected. Check the voltage in the socket and make sure that the compressor is not overheating.
Where can you find the relay markings?
The marking is usually located on the side or top edge of the black plastic case. Look for the abbreviations RTP, RZ, 17.50, 3394 and numbers indicating current (for example, 1.4A, 2.2A). If the inscription is erased, look for the compressor model (for example, FK 8160, SC 18 CL) and select a relay from compatibility catalogs.
How much does it cost to replace a relay in the service?
The cost consists of the price of the part itself (usually from 500 to 2000 rubles depending on the model) and the cost call the master. Self-replacement allows you to save on work, which can amount to up to 70% of the total bill.