The refrigerator stopped freezing, and Does the compressor only make a quiet hum or click but does not start? In 80% of cases, the reason lies in the failure of the start relay. This small element is responsible for applying voltage to the motor windings, allowing the compressor to start and begin pumping refrigerant. If the relay is burnt out or stuck, the circuit does not close and the motor does not receive the necessary impulse to start.
Replacing this part on your own is a real task for a home craftsman who has basic skills in working with tools. The main thing here is not only to physically install a new spare part, but also to do it correctly, observing polarity and safety precautions. A connection error can lead to a short circuit or re-burnout of an expensive compressor.
In this article we will look at how to identify the malfunction, choose the appropriate analogue and, most importantly, how to correctly connect the relay on the refrigerator so that it works again. We will look at the features of various types of devices and their installation diagrams, which will help you avoid common mistakes when repairing household appliances.
The principle of operation and types of starting relays
The starting relay is an electromechanical switch that is activated when the refrigerator is turned on. Its task is to briefly supply current to the starting winding of the compressor, creating torque. As soon as the engine picks up speed, the relay opens the starting winding circuit, and the motor continues to operate on the main winding. Without this mechanism, starting a single-phase motor would be impossible.
There are two main types of such devices: induction (electromagnetic) and posistor (thermal). Induction relays they work due to the current flowing through the winding of the coil, which draws in the core and closes the contacts. They are installed strictly vertically and are position sensitive. PTC models use a thermoelement (posistor), which is heated by current and changes the resistance, opening the circuit. They are more reliable and versatile in installation.
It is important to understand that different models of refrigerators, be it Indesit, Atlant or Beko, may require different types of relays. There are no universal solutions “for all occasions,” although some manufacturers produce adaptable options. The wrong choice of device type will result in the compressor either not starting or constantly humming and overheating.
⚠️ Attention: It is strictly forbidden to leave the refrigerator plugged in if the relay is not installed or the contacts are open. The compressor will hum, trying to start, which will lead to rapid overheating of the windings and an interturn short circuit.
You can determine the type of your relay by its appearance and number of contacts. Induction often have a more complex mechanical structure with a movable core, while posistor ones look like a compact plastic block with a ceramic element inside. When purchasing a new part, be sure to compare the markings and appearance with the old spare part.
Fault diagnosis before replacement
Before buying a new part and disassembling the refrigerator, you need to make sure that the problem is in the relay. Symptoms may be similar to a breakdown of the compressor or thermostat itself. Primary diagnosis begins with a visual inspection and listening to the operation of the unit. If you hear a characteristic click, followed by a motor hum that lasts 3-5 seconds, and then another click and silence, this is a classic sign of a faulty starter.
To accurately check the relay, it must be removed from the compressor. Unplug the refrigerator, remove the rear protective cover and carefully disconnect the connector. A visual inspection may reveal melted contacts, blackening of the plastic, or a characteristic burning smell. If the relay body has cracks or signs of overheating, its replacement is required.
Checking with a multimeter is the most reliable diagnostic method. In continuity mode, check the continuity of the circuit. For posistor relays, the resistance at room temperature should be in the range of 20-50 Ohms. If the device shows infinity or zero, the part is faulty. Induction relays are checked for coil closure and mobility of the core, which must move freely inside the housing.
It is also worth checking the condition of the contacts on the compressor itself. Sometimes oxidation occurs not at the relay, but at the mating pins of the motor. Sanding the contacts with fine sandpaper may solve the problem without replacing the part. However, if the relay is “stuck” in the closed state, it could have already damaged the starting winding, so installing a new element is required.
Preparation for dismantling and tools
For successful work, you will need a minimum set of tools. The main requirement is safety and accuracy. Do not use too powerful tools where precision is needed so as not to damage the plastic elements or tubes of the refrigeration system.
- 🛠️ Screwdrivers: cross and flat (for removing the protective casing and clamps).
- 🔧 Pliers: preferably with narrow jaws for gripping contacts.
- 🧤 Gloves: dielectric or just thick working pliers to protect hands.
- 📸 Smartphone: for photographing the connection diagram before removal.
First of all, disconnect the refrigerator from the power supply. This basic safety ruleis something that cannot be ignored. Even if the relay appears burnt, there may still be residual voltage in the circuit. Move the unit away from the wall to gain access to the rear panel. Remove the cardboard or metal cover covering the compressor area.
Inspect the compressor carefully. The relay is usually placed on three contacts extending from the motor housing and secured with a plastic frame or metal bracket. Before pulling the part, take a photo. This will help you correctly navigate when installing a new element, especially if you do not remember the position of the connectors.
☑️ Preparing to replace the relay
If the relay is held on a metal bracket, carefully bend its edges with a screwdriver. Plastic latches require gentle pressure with a flat tool. Do not apply excessive force to the compressor tubes - they are filled with freon under pressure, and their damage will lead to gas leakage and expensive repairs.
The process of removing the old relay
Removing the old relay is a step that requires care. Often, over years of use, the plastic “sticks” due to temperature, and the contacts oxidize. Sudden movements can lead to breakage of the plastic ears or, worse, breakage of the suitable wires.
Gently rock the relay from side to side while simultaneously pulling it away from the compressor contacts. If it fits very tightly, you can slightly heat the case with a hairdryer (without overheating!) to soften the plastic. Never use an open flame. If individual wires, rather than a common connector, connect to the relay, they must be disconnected, having first marked each wire with a marker according to the diagram.
After removal, inspect the contact group on the compressor. There should be no soot or oxides on it. If necessary, clean the pins with fine sandpaper or a file. Also check the integrity of the wires going to the relay: the insulation should not be melted, and the copper wires should not stick out.
What to do if the contacts are burnt?
If you see heavy carbon deposits on the contacts of the relay or compressor, this indicates poor contact and sparking. Simply cleaning them may not be enough - it is better to replace the terminals. If the insulation of the wires is burnt, they need to be increased or replaced, using heat shrink for protection.">Burnt contacts increase resistance, which leads to heating and repeated breakdown.
There is no need to dispose of the old relay, but you also don’t need to leave it lying around in the toolbox. It is better to save it until the functionality of the new part is fully tested. Sometimes new parts are defective, and a quick return replacement is possible or comparison will be very useful.
Connection diagram and installation of a new relay
Installing a new relay is the most crucial moment. Here it is critical to maintain the correct orientation. There is often a marking on the relay body and on the compressor contacts: R (Run - working winding), S (Start - starting winding) and a grounding symbol or common wire. You cannot mix them up - this will lead to instantaneous combustion of the new part.
The orientation of the device depends on its type. Induction relays have an arrow on the body indicating the "UP" direction. They must be installed strictly vertically. PTC relays are less demanding, but it is still recommended to install them in the same position as the old device. Incorrect position may impair the operation of the thermal breaker.
| Relay Type | Orientation | Sensitivity | Typical Brands |
|---|---|---|---|
| Induction | Strictly vertical (arrow up) | High (afraid of vibration) | Atlant, old models |
| Posistor | Any (preferably as it was) | Low (shockproof) | Indesit, Samsung, LG |
| Thermal (protection) | Tight to the motor housing | Responses to current and heat | Universal |
Push the relay onto the compressor contacts until it stops. It should fit tightly, without backlash. If you are using an adapter frame, make sure it snaps onto the motor housing. Then connect the wires: red (or brown) usually goes to the starting winding, white (or black) to the working winding. Check that the connection is secure by lightly pulling the wires.
After connecting, check that the wires do not touch hot parts of the compressor or sharp edges of the metal casing. Vibration can cause the insulation to wear off, resulting in a short circuit to the housing. Secure the wires with standard clamps or plastic clamps.
First start-up and performance check
Before screwing the lid and putting the refrigerator back in place, it is necessary to conduct a test run. This will ensure that the connection is correct and that there are no extraneous sounds. Plug the cord into the outlet and listen carefully.
The compressor should start with a characteristic hum 1-3 seconds after the relay clicks. If you hear a buzzing sound that ends abruptly with a click, and this repeats several times, turn off the refrigerator immediately. This means that the relay does not open the circuit or the compressor is jammed. If the motor runs smoothly, without vibration or hum, let it run for 10-15 minutes.
Check the heating of the relay itself. It may get a little warm, but it shouldn't be so hot that you can't touch it. Also check to see if the compressor housing is getting excessively hot. If all parameters are normal, you can install a protective cover.
⚠️ Attention: If, after replacing the relay, the compressor hums but does not start, do not keep it turned on for more than 30 seconds. This may (burn out) the motor's starting winding. It is better to immediately turn off and recheck the circuit.
Make sure that when the refrigerator is operating, the relay does not make loud clicks during operation (only when starting and stopping). A constant clicking sound indicates a faulty thermostat or relay. After a successful test, carefully secure the back panel without pinching the wires and tubes.
Common mistakes and expert advice
When repairing things on their own, technicians often make mistakes that nullify all their efforts. One of the most common is ignoring the relay type. An attempt to install a posistor relay instead of an induction relay (or vice versa) without taking into account the features of the circuit will lead to unstable operation.
Another mistake is poor contact. If you do not tighten the connector or leave oxidized contacts, the resistance at the connection point will increase. This will cause local heating, melting the plastic and causing further failure. Always clean the contacts and secure the connections tightly.
Some try to “revive” an old relay by opening the case and stripping the contacts. This can only be done as a temporary measure in the field. At home The service life of a restored relay rarely exceeds a week., since the tightness and calibration of thermal gaps are broken. It is safer and more reliable to buy a new part.
It is also worth mentioning power compatibility. The relay is designed for a certain compressor power (for example, 1/8, 1/6, 1/4 hp). Installing a relay that is too weak on a powerful motor will lead to its rapid failure. Always look at the wattage label when purchasing.
Can a universal relay be used?
Yes, there are universal starting relays (such as the PTC series) that are suitable for a wide range of wattages. They are often sold complete with adapter frames and wires. However, they are not always ideal in size or characteristics, so a native spare part is always preferable.
Why does a new relay burn out immediately after installation?
There may be several reasons: a jammed compressor (mechanical problem), a malfunction in the electrical network (voltage surges) or an incorrect connection diagram. It is also possible that the new relay itself is defective. Before reinstallation, be sure to check the free play of the compressor shaft.
Where can you find the power marking on the compressor?
The power and model of the compressor are indicated on a sticker located on the metal body of the motor, next to the tubes. The refrigerant type, volume and electrical parameters will be indicated there. It is easiest to choose the correct relay based on the compressor model.
Is it dangerous to change the relay yourself?
Replacing the relay is safe if you follow electrical safety rules (disconnect from the network) and do not damage the copper tubes with freon. The main danger is electric shock when the device is turned on or fire due to a short circuit. If you are not confident in your abilities, it is better to call a specialist.