A sudden stop of the refrigerator often takes you by surprise, turning into a serious household problem. One of the main suspects in this situation is the start relay, which is responsible for starting the compressor engine. If this small but important element fails, the motor simply cannot gain the necessary speed to operate, and the chamber stops cooling.
Independent relay testing is an accessible procedure that does not require deep knowledge of electrical engineering or expensive equipment. It is enough to have a basic set of tools and an understanding of the operating principle of the unit at hand. In this article we will look in detail at how to identify a breakdown, what tools will be needed and when the part really needs to be replaced.
Before you start disassembling, it is important to make sure that the work is safe. Any manipulations with electrical components require completely disconnecting the device from the network. Ignoring this rule may result in electric shock or damage to the electronics of the refrigerator.
Signs of a faulty start relay
The first signal that starting relay has failed is the characteristic behavior of the compressor. Instead of the usual smooth hum of a running motor, you may hear short clicks repeated at certain intervals. This indicates that the engine is trying to start, but the protection immediately opens the circuit.
Often equipment owners notice that the refrigerator turns on, runs for a few seconds, and then there is a loud click and the unit goes silent again. In some cases, the compressor may not even attempt to start, remaining completely silent, although the power indicators on the panel may be illuminated. The lack of cold in the chambers when the fan is running (if the model has one) should also alert you.
Visual inspection can provide additional clues. If the relay has damaged housing, melted contacts, or emits a burning smell, the problem is obvious. However, often there are no external defects, and a more in-depth diagnosis is required.
⚠️ Attention: If after the click the compressor continues to hum, but does not start for more than 10-15 seconds, immediately unplug the refrigerator. Long-term operation in this mode (“humming without starting”) can lead to burnout of the motor windings, which will require expensive repairs or replacement of the entire unit.
Preparation for diagnostics and necessary tools
To properly check the relay on the refrigerator, you will need a minimum set of tools, which most home craftsmen have. The main device will be a multimeter (tester), which allows you to measure the resistance and integrity of the circuit. Without it, diagnostics will be purely visual, which does not always give an accurate result.
In addition to the measuring device, prepare a flat-head and Phillips screwdriver for removing the protective panels and dismantling the relay itself. You may also need pliers to carefully remove the terminals if they are tight. It will not be superfluous to use fine-grained sandpaper or a needle file to clean the contacts if you plan to restore the part.
It is important to ensure good lighting of the work area, since the compressor compartment is often dark. Before starting work, be sure to disconnect the refrigerator from the power supply and move it away from the wall to gain free access to the rear of the unit.
☑️ Tools for checking the relay
Removing the start relay
The process of removing the relay begins with access to the compressor, which is usually located at the bottom rear of the refrigerator. In some models, for example Indesit or Atlant, you may need to remove the rear metal cover covering the engine compartment. The mounting screws are unscrewed with a standard screwdriver.
Find a black cylindrical or pear-shaped compressor tank. A plastic casing is placed on the side or top of it - this is the starting relay. It can be secured to a bracket, latches, or simply sit tightly on the three contact pins of the compressor. Carefully remove the casing, being careful not to damage the associated wires.
Before completely removing the part, remember or photograph the wiring diagram. Although it is difficult to mix up connectors due to their shape and markings, visual reference will help avoid assembly errors. Disconnect the terminals and remove the relay from its seat.
Mounting features in different brands
In Bosch and Siemens refrigerators, the relay is often fixed with a metal bracket, which must be carefully pressed out. In LG and Samsung models, systems with latches on a plastic case are common. In old Soviet refrigerators and their modern analogues (Eagle, Biryusa), the relay can simply be put on the contacts without additional clamps, being held in place due to the tight fit and weight.
Visual inspection and check of a hammer relay
There are two main types of relays: electromagnetic (with a coil and a movable core) and posistor (solid state). Electromagnetic ones are often called “hammer” because of the characteristic sound during operation. Inside such a device there is a coil and a movable element, which, under the influence of current, closes the contacts.
When visually inspecting, pay attention to the condition of the contacts. If they show black carbon deposits, oxidation or traces of melting, this is a sure sign of overload or poor contact. Also check the integrity of the coil: it should not have breaks or signs of thermal effects.
Try to gently shake the relay next to your ear. If knocking or rattling is heard inside, this may mean that the mechanism is jammed or a moving element has broken off. In good condition, the internal parts should fit tightly, although light movement of the core is acceptable in some designs.
⚠️ Attention: If you find traces of soot inside the relay or there is a persistent burning smell, further operation of such a part is impossible. An attempt to clean the contacts in this case is a temporary measure that will not solve the reliability problem. It is better to immediately purchase a new original component.
Diagnostics with a multimeter
The most accurate way how to check a refrigerator relayis to use a multimeter in resistance measurement mode (Ohm). This method allows you to assess the integrity of the windings and the condition of the contacts with high accuracy, eliminating guesswork.
To check the electromagnetic relay, switch the tester to the continuity or resistance measurement mode. Connect the probes to the coil contacts. The device must show a certain resistance (usually from 30 to 60 Ohms, depending on the model). If the screen displays one (infinity), it means there is a break in the coil and the relay must be replaced.
Next, we check the contacts. In the initial position (the relay lies on the table), the contacts of the main circuit should be open (the resistance is infinite). If you turn the relay over (simulating operation under the influence of gravity or a magnetic field, depending on the design), the contacts should close and the device will beep. Lack of response indicates a mechanical failure or sticking.
For posistor relays (PTC) the procedure is slightly different. The posistor resistance at room temperature should be low (several tens of ohms). If the multimeter shows an open circuit or resistance close to zero (short circuit), the part is faulty.
Table of typical resistance values
When diagnosing, it is important to understand which readings are considered normal and which indicate a malfunction. Values may vary depending on the manufacturer and type of relay, but there are average ranges that are worth focusing on.
| Relay type / Element | Normal resistance | Fault symptom | Action |
|---|---|---|---|
| Coil (electromagnetic) | 30 – 60 Ohm | Infinity (∞) | Replacing the relay |
| Posistor (PTC) | 10 - 50 Ohm (cold) | 0 Ohm or ∞ | Replacing the relay |
| Contacts (closed) | 0 - 1 Ohm | More than 5 Ohm | Cleaning or replacement |
| Thermal relay (bimetal) | 0 Ohm | Infinity (∞) | Replacement of thermal protection |
If your measurements are radically different from the data in the table, this is a reason to think about purchasing new part. Remember that the cost of the relay is not comparable to the cost of the compressor, so saving on diagnostics in this case is not worth it.
Replacement and startup after repair
If the check confirms a malfunction, the relay must be replaced. Installation of a new part is carried out in the reverse order of removal. Make sure that the connectors are pushed all the way in and secured, and that the relay itself sits tightly on the compressor terminals.
After assembly, do not rush to load food into the refrigerator. Let the unit run idle for about 2-3 hours. This will make sure that the compressor starts the first time, runs smoothly and reaches the required temperature.
During the first start-up, listen carefully to the sounds. The absence of unnecessary clicks, hums or vibrations indicates a successful repair. If the refrigerator begins to freeze, you can consider the task completed.
Frequently asked questions (FAQ)
Is it possible to repair a relay if it is burned out?
Theoretically, you can try to clean the contacts or replace the coil by choosing an analogue. However, in practice, such measures provide a temporary effect. The relay is a consumable item, and after overheating its characteristics change. It is more reliable and safer to buy a new original part.
Why does the relay click, but the refrigerator does not turn on?
The click means that the relay is trying to start the compressor, but the current in the circuit is insufficient or too high, and the protection opens the contacts. This can be caused either by a breakdown of the relay itself or by an interturn short circuit in the compressor windings. Complex diagnostics are required.
Where can I find the markings for purchasing a new relay?
The markings are usually applied to the plastic body of the relay itself. You can also find the part number in the technical documentation of the refrigerator or on the compressor nameplate. When purchasing in a store, be sure to show the seller a photo of the old part or name the exact model of the refrigerator.
Is it dangerous to change the relay yourself?
The procedure is not difficult if electrical safety rules are followed. The main thing is to completely de-energize the device before starting work. If you are not confident in your abilities or are afraid of damaging the wiring, it is better to contact a professional technician.