Sudden stoppage of the compressor or, conversely, its continuous operation without cooling are classic symptoms indicating a malfunction in the engine starting circuit. Often the cause is the starting or protective device, which is easy to replace yourself if the problem is correctly diagnosed. In this article, we will look at how to check the functionality of a refrigerator relay using available tools and visual inspection, and will also provide video materials for clarity.
Before proceeding with disassembly, it is important to understand that starting relay is responsible for supplying voltage to the starting winding at the time of start, and thermal relay protects the motor from overloads. If one of these elements fails, the compressor either does not start at all, producing only a hum, or turns on and turns off immediately. Correct diagnostics will allow you to avoid purchasing unnecessary spare parts and unnecessary calls to the technician.
Signs of a faulty starting relay
The first step in diagnosis is to analyze the behavior of your refrigerator. If you notice that compressor tries to start, hums for a few seconds, and then a characteristic click is heard and silence sets in - this is a sure sign of a problem. In such a situation, the engine does not receive the necessary impulse to rotate, and the thermal protection is triggered, breaking the circuit.
Sometimes the situation looks different: the motor runs continuously without turning off, but the temperature in the chambers does not drop to the required values. This may indicate that the relay contacts are “stuck” in the closed state, and the starting winding is constantly energized, which is detrimental to it. It is also worth paying attention to external signs:
- 🔥 The appearance of a burning smell or melted plastic in the compressor area.
- 🔊 Uncharacteristic crackling or loud clicks when trying to turn on.
- ❄️ Lack of cold when the fan is running (in systems No Frost).
It is important not to ignore these signals, since prolonged work with a faulty starting device can lead to combustion of the compressor itself, the replacement of which is not economically feasible. If you hear the refrigerator “hiccupping”—it turns on for a couple of seconds and turns off—immediately unplug the appliance.
⚠️ Attention: If after the click you smell a strong burning smell or see sparking, further diagnostics without the skills of an electrician can be dangerous. In such cases, it is better to call a specialist.
Dismantling and visual inspection of the device
To carry out an accurate diagnosis, it is necessary to remove the suspicious element. Before starting any work be sure to disconnect the refrigerator from the power supply. Safety is priority number one. Locate the compressor, which is usually located at the lower rear of the unit. A plastic box is attached to its protruding rod (extending from the motor housing) - this is our desired device.
Carefully remove the protective cover, if any, and disconnect the block with the wires. The relay itself is usually held on by latches or simply placed on the contacts of the compressor. Depending on the model, it can be combined with a thermal relay or made separately. When removing, be careful not to damage the suitable wires.
☑️ Preparing to remove the relay
After removal, carry out a thorough visual inspection. The body should not have cracks, and the insides should not have signs of burning. If you see that the plastic has turned black and the contacts have melted, then the answer to the question of operability has already been received - the device is faulty. Also pay attention to the condition of the terminals: oxidation may damage the contact.
Checking a posistor relay with a multimeter
Modern refrigerators are most often equipped with posistor starting relays. The principle of their operation is based on the property of a posistor (special resistor) to heat up and increase its resistance, opening the starting winding circuit after the engine starts. You can check such an element using multimeter.
Take the tester, switch it to resistance measurement mode (usually 200 Ohms). Connect the probes to the relay contacts. When cold, the resistance of the posistor should be low, usually in the range of 10 to 50 ohms. If the device shows one (open) or zero (short circuit), the part requires replacement.
Nuances of checking a posistor
A posistor is a thermistor. Immediately after testing, when it is heated by your touch or the tester's current, its resistance may be high. To recheck it, it needs to cool for 3-5 minutes so that it “closes” again.
In addition to checking the resistance, it is worth making sure that the internal connections are intact. Ring the contacts going to the coil and compressor contacts. Some designs may have a capacitor inside - check for swelling. Even if the external parameters are normal, but the refrigerator does not start, it is better to replace the relay with a known good one, since it is a consumable item.
Diagnostics of a relay with a current coil
In older models of refrigerators (for example, Soviet or early imported ones) devices with a current coil and a moving core are used. The mechanism of their action is based on electromagnetic induction: when starting, the current is high, the core is retracted and closes the contacts of the starting winding. When the motor accelerates, the current drops and the core falls under the action, opening the circuit.
Checking such a relay is simple and does not always require tools. Shake the device near your ear. If you hear the core knocking, this is a good sign, it means it is not stuck. However, for a complete diagnosis, you need to check the coil for a break. The coil resistance should be close to zero (or very low), and the contacts in the vertical position should be open.
Inspect the contacts inside the housing. If they are burnt or covered with soot, you can try to carefully clean them with fine sandpaper, but this is a temporary measure. Mechanical wear of moving parts often leads to the fact that the relay stops opening the circuit in time, which leads to overheating of the motor.
- 🧲 Check the mobility of the core - it should move freely inside the coil.
- 🔌 Make sure that the contacts are not welded to each other.
- 📏 Measure the resistance of the coil - it should not be infinite.
Table: Comparison of types of starting relays
To make it easier for you to navigate the variety of parts, we have compiled a comparative table of the main characteristics. Understanding the type of your device will help you quickly find a replacement and correctly diagnose.
| Characteristics | Posistor relay | Relay with coil (induction) | Thermal relay (protective) |
|---|---|---|---|
| Principle of operation | Heating of the crystal and increase in resistance | Electromagnetic retraction of the core | Heating of the bimetallic plate |
| Location | Often in a common housing with thermal | Individually or in tandem with thermal | Directly on the compressor contacts |
| Typical malfunction | Crystal destruction (break) | Contact sticking or coil | Loss of plate elasticity |
| Check | Resistance measurement (Ohm) | Visual + coil ringing | Ringing in cold state |
As can be seen from the table, the approach to testing depends on the design. Thermal relay, which is often paired with a starter, is checked for circuit integrity in a cold state. If the circuit is broken at room temperature, the protection is faulty and requires replacement, even if the motor itself is intact.
Common mistakes when replacing them yourself
Many users, having figured out how to check the refrigerator relay for functionality using video, proceed to replace it, making typical mistakes. One of the most common is ignoring labeling. Even if the new relay is similar in appearance and the contact groups are the same, its current characteristics may differ. Installing a part with an inappropriate cut-off current will lead to frequent false shutdowns or, conversely, to overload.
Also often forgotten about the polarity of the connection, although for most alternating currents this is not critical, the location of the phase and zero contacts in some electronic circuits can matter. Be sure to photograph the original position of the wires before removal.
⚠️ Attention: Specifications of compressors and compatible relays may vary depending on the specific modification of the refrigerator. Always check the part number on the body of the old relay with the catalog number of the new one.
Do not try to “revive” a burnt-out relay by shorting the contacts directly. This will lead to instantaneous combustion of the compressor starting winding. If the relay is faulty, just replace it with a new one. Saving on this small part could cost you a new refrigerator.
Video instructions and visual examples
It is useful to consolidate theoretical knowledge with visuals. The video format allows you to see the nuances: how exactly the part is held, how it cracks during inspection, what carbon deposits look like. We have selected key points that you should pay attention to when watching training videos on the topic.
In high-quality video instructions you will see the process of “dialing” with a multimeter in real time, where the master comments on the readings of the device. A cross-sectional comparison of a serviceable and a faulty posistor is also often demonstrated. Pay attention to the safety precautions demonstrated by professionals.
- 🎥 Look for a video that shows a specific model of your refrigerator or type of compressor (for example, Atlant, Indesit, Beko).
- 🎥 Pay attention to the clicking sound - in the video you can clearly hear what a working device sounds like.
- 🎥 Study the process removing the terminals so as not to tear them off along with the wire.
Remember that even a high-quality video cannot replace compliance with safety precautions. If you are not confident in your abilities after viewing the instructions, it is better to entrust the work to a professional. However, if you decide to repair it yourself, accuracy and attentiveness are your main tools.
Where to look for original spare parts?
Original relays often have the logo of the refrigerator manufacturer, but are produced by specialized factories (for example, Ranco, Danfoss). When searching for videos or spare parts, you can use the cross numbers of these manufacturers.
Questions and answers (FAQ)
Is it possible to start a refrigerator without a relay?
Technically, you can start the motor by applying voltage directly to the starting winding, but doing this is strictly prohibited in domestic conditions. Without a relay, the engine will burn out in a few seconds, since the starting winding is not designed for long-term operation. This is an emergency method for checking the motor itself, and not a method of operation.
Why does the new relay click, but the refrigerator does not. is it freezing?
If the relay is working properly (clicks), but there is no cold, the problem may be deeper: the compressor itself is faulty (interturn short circuit, wedge of the piston group), there is a blockage in the freon circulation system or there is a leak. It is also worth checking the capacitor, if it is in the circuit.
How often do you need to change the starting unit. relay?
The starting relay does not have a scheduled replacement period. It is replaced only when it fails. Under normal operating conditions (stable voltage in the network), it can last 10 years or more. Frequent power surges shorten its life.
Is a universal relay suitable for my refrigerator?
There are universal kits, but they must be selected strictly according to the compressor power (in watts or horsepower). Incorrect selection of the current characteristic will lead to incorrect operation. It is better to look for the original or a complete analogue by the catalog number.