A sudden stop of the refrigerator compressor often becomes an unpleasant surprise, especially when there are products inside that require strict temperature conditions. In most cases, the cause of the breakdown is the failure of the starting relay, which is responsible for starting the engine and protecting it from overloads. Replacement of this part This is one of the most common procedures in the repair of household appliances, which can be done independently with a minimum set of tools.
Before taking active steps, it is necessary to clearly understand that working with electrical appliances requires compliance with safety precautions. Starting relay - this is a small but critical component, without which the motor will not be able to move from rest to operating mode. In this article we will analyze in detail the process of diagnostics, dismantling the old element and correctly connecting the new device to the electrical network.
It should immediately be noted that there are different types of starting devices, and their design can differ significantly depending on the model of the refrigeration unit. Incorrect connection or installation of an unsuitable part can lead to burnout of the compressor windings, so it is important to act consistently and carefully study the markings. An exact match of the relay model with the original catalog number is the only guaranteed way to avoid repeated breakdowns.
Operation principle and types of starting relays
For successful repairs, you need to understand the basic operating principle of the unit that you plan to replace. Start relay performs the function of an automatic switch that supplies voltage to the engine starting winding only at the moment of start, and then turns it off when the motor reaches the required speed. Without this mechanism, the engine would only hum, but would not start.
There are two main types of devices that are most often found in modern and old refrigerators. The first type is induction-dispatching relayswhich operate on the basis of an electromagnetic coil and a movable core. The second type is posistor (thermal) relays, where the role of a switch is performed by a semiconductor element that changes its resistance when heated.
- 🔹 Induction models are more often found in old Soviet refrigerators and some modern units with heavy compressors.
- 🔹 PTC devices are more compact, have no moving parts and are considered more reliable in operation.
- 🔹 Thermal relays also perform a protection function, opening the circuit when the temperature of the windings critically increases.
Determine the type of your device can be done visually after removing the back cover of the refrigerator. If you see a coil of copper wire and a movable rod inside the plastic case, this is an induction mechanism. If there is a ceramic or plastic coated disk inside, it is a posistor.
⚠️ Attention: Visually similar relays may have different electrical circuits. Never install a part whose markings do not match the original, even if it physically fits in size.
What is the danger of incorrectly installing a relay?
If you install a relay with the wrong response current, the compressor may either not start (too high a threshold) or burn out from overheating (too low a shutdown threshold). In addition, the contacts may stick, which will lead to a constant hum of the motor without rotation of the shaft.
Diagnostics of the fault before replacement
Before buying a new part and disassembling the unit, you should make sure that the problem lies in the starting device, and not in the compressor itself. Often the symptoms can be similar: the refrigerator does not turn on, a click is heard, but the motor is silent or hums for a few seconds, after which the click is heard again and silence sets in.
The first step should always be to visual inspection remove the part. Carefully open the relay housing (usually it is held in place by latches) and inspect the insides. If you see blackening, melted plastic or smell a burning smell, then the diagnosis is obvious - the device is burnt out and requires replacement.
For a more accurate diagnosis, you can use a multimeter in dial mode. Check the integrity of the contacts: in a normally closed state, the circuit should ring, and when the relay is turned over (imitation of operation), it should open. For posistors, the resistance should be low when cold and increase when heated.
If checking with a multimeter shows an open circuit where there should not be one, or a short circuit, the part is faulty. However, it is worth remembering that sometimes the relay fails due to problems with the compressor itself, for example, when the piston group jams.
Preparation of tools and materials
High-quality repairs are impossible without proper preparation of the workplace and tools. You will not need complex professional equipment, but the basic kit of a home craftsman should be fully equipped. Screwdrivers (cross and flat) will be needed to remove the protective cover of the compressor and fix the clamps.
Also be sure to prepare pliers or pliers with narrow jaws for working with terminals that can fit very tightly. To clean the contacts, if necessary, fine sandpaper or a file will be useful, although when replacing the relay with a new one, this is usually not necessary.
- 🔸 Multimeter for checking circuits and voltage.
- 🔸 Insulating tape or heat shrink tubing to protect connections.
- 🔸 Flashlight for illuminating hard-to-reach places in the compressor niche.
It is important to ensure good lighting of the work area, since the back of the refrigerator is often dusty and dark. If you plan to solder the contacts (which is rare with a simple replacement), you will need a soldering iron and solder.
⚠️ Attention: Before starting any work, be sure to disconnect the refrigerator from the electrical network. Working under voltage is deadly and can lead to electric shock.
Removing the old start relay
The process of removing the old device requires care so as not to damage the suitable wires and the compressor itself. Typically, the relay is placed on three contact pins extending from the motor housing and secured with a metal bracket or plastic clamp.
First remove the protective cover covering the compressor compartment. It can be bolted on or simply snapped on. Clear the area around the motor from dust and cobwebs so that it does not get inside the electrical part. Then carefully disconnect the wires going to the relay, having first noted or photographed their location.
Remove the retaining bracket that presses the relay to the compressor housing. After this, grab the relay body and, using light rocking movements, remove it from the contact pins. Do not use excessive force so as not to break the ceramic insulators or the pins themselves.
☑️ Dismantling procedure
If the old relay sits very tightly and cannot be removed, it may have become stuck due to time and temperature. In this case, you can slightly warm up the case with a hairdryer, but this must be done extremely carefully so as not to melt the plastic wiring elements.
Connection diagram and installation of a new relay
Installing a new device is the most critical stage, requiring maximum care. The main task is to correctly orient the relay relative to the compressor, since the pins have a strictly defined purpose. On the body of most relays there are markings: S (Start) for the starting winding, R (Run) for the working winding and L or N for the line or neutral.
The connection diagram may vary, but the most common configuration is the following: the top two pins are the compressor windings, and the bottom (or side) is the power supply. It is important that when installing the relay in a vertical position (pins down), it fits tightly and without distortion.
| Contact marking | Purpose | Wire color (often) | Location |
|---|---|---|---|
C or L |
Line (phase) | Red, brown | Bottom/Side |
S |
Start winding | Black, blue | Upper left |
R |
Working winding | White, green | Upper right |
GND |
Grounding | Yellow-green | Separately on the body |
After the relay is put on the pins, return the fixing bracket to its place. It must hold the device securely so that the vibration of a running motor does not loosen the contacts. Then connect the wires to the appropriate terminals according to the photo or diagram you took earlier.
Make sure that no wires touch the metal housing of the compressor or the sharp edges of the bracket. If necessary, insulate the joints with additional insulating tape.
First start-up and performance check
After installation is completed, you can proceed to testing. Plug in the refrigerator and listen carefully. After a few seconds, a characteristic click of the relay should be heard, followed by the smooth hum of the starting compressor.
If the motor starts and runs smoothly, without jerking or extraneous sounds, it means the replacement was successful. Let the refrigerator operate for about 15-20 minutes, periodically checking the temperature of the condenser (grid at the back) - it should gradually heat up.
If the compressor hums but does not start, or immediately knocks out the circuit breaker, immediately disconnect the device from the network. This may indicate an incorrect installation of the relay, a malfunction of the newest part, or, worse, a problem with the motor windings.
Also check the current consumption if you have current clamps. It must correspond to the nominal values indicated on the compressor nameplate. Exceeding current indicates overload and possible imminent breakdown.
Frequent errors and precautions
When doing their own repairs, beginners often make typical mistakes that can negate all efforts. One of the most common is ignoring contact cleaning. If oxide or carbon remains on the compressor pins, the new relay will quickly fail.
Another mistake is using a relay with an inappropriate response current. Even if the unit physically fits into place, its electrical ratings may not match the capacity of your compressor. Always check the part numbers.
- 🚫 Attempting to repair a burnt relay by stripping the contacts (a temporary measure that is dangerous for the motor).
- 🚫 Installing the relay upside down (disturbs the operation of the mechanical elements).
- 🚫 Ignoring the condition of the wires (melted insulation may cause a short circuit).
⚠️ Attention: Refrigerator manufacturers may make changes to the design of components without prior notice. Always check the visual correspondence and electrical parameters of the new part with the original before installation.
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can apply voltage directly to the starting winding manually, but this is extremely dangerous and requires skill. Without protection, the compressor can burn out in a matter of minutes. It is not recommended to do this at home.
Questions and answers (FAQ)
Is it possible to install a universal relay on any refrigerator?
Universal relays exist, but they require precise adjustment or have a limited range of application. It is best to look for an original spare part or a complete analogue by catalog number, since the cut-off current parameters differ for different compressor models.
Why did the new relay burn out immediately after installation?
There may be several reasons: the compressor itself is faulty (turn-to-turn short circuit), the wires are connected incorrectly, or power surges occur in the network. It is also possible that the new relay was defective or did not match the starting current.
How often do you need to change the starting relay?
The service life of the relay is on average 5-10 years, but depends on the number of on/off cycles and the stability of the voltage in the network. If the refrigerator is in a room with unstable electricity, the service life of the part is reduced.
Is it dangerous to change the relay yourself?
If you follow electrical safety rules (disconnect from the network), the risk is minimal. The main danger is electric shock when the device is turned on or damage to the compressor if installed incorrectly. If you are not confident in your abilities, it is better to call a specialist.