Sudden stoppage of the refrigerator or the appearance of loud clicks often indicates problems in the electrical circuit of the compressor. Start relay is a key element that ensures the engine starts, and its failure blocks the normal functioning of the entire system. If you hear a characteristic knock, but the engine does not start, or the compressor only works for a few seconds before shutting down, most likely this particular unit needs to be checked.
Self-diagnosis allows you to save time and money on calling a technician, since the procedure does not require complex specialized equipment. A basic understanding of the principles of operation of electrical appliances and the presence of a multimeter is enough. In this article, we will analyze in detail the algorithm of actions that will help you accurately determine the condition of the part and make a decision about replacing it.
Before starting disassembly, make sure that you follow safety precautions when working with electrical appliances. Disconnection from the network is the first and mandatory condition, ignoring which can lead to electric shock. Only after complete de-energization can you begin to dismantle the rear panel and remove the necessary components for testing.
⚠️ Attention: Before starting any work, make sure that the power cord is completely removed from the outlet. Residual voltage in the capacitors can be dangerous, so let the device stand for 10-15 minutes after switching off.
Symptoms of a faulty starting relay
You can determine that the problem lies in the starting relay by a number of indirect signs that appear in the behavior of the refrigeration unit. Most often, owners are faced with a situation when compressor tries to start, makes a loud click and immediately goes quiet. This cycle can be repeated at intervals of several minutes until the thermal relay turns off the power supply completely to avoid burnout of the windings.
Another obvious sign is overheating of the motor. If you touch the back wall of the refrigerator or the compressor itself and feel that it is hot, this indicates that the engine is running in emergency mode or is trying to start to no avail. In normal condition thermal protection should work, but frequent on-off cycles indicate the inability of the relay to close the starting winding.
- 🔊 Loud clicks when trying to start the motor.
- 🌡️ Strong heating of the compressor housing when the cooling is not working.
- ❌ Complete lack of reaction of the refrigerator when plugged in.
- ⚡ Knockout of plugs or circuit breakers in the electrical panel at start.
Sometimes a relay malfunction leads to the fact that the refrigerator is working, but does not reach the desired temperature. This happens if the contact does not close completely or with high resistance, which is why starting winding does not receive enough impulse to accelerate the rotor. In such cases, the motor may hum, but not go into operating mode, which will ultimately lead to its combustion.
Preparation for diagnostics and dismantling
To carry out a quality test, you will need a minimum set of tools, which most home craftsmen can find. The main device will be multimeter (tester), which allows you to measure resistance and test circuits for open circuits. You will also need a flathead and Phillips screwdriver to remove the protective covers and pliers to carefully remove the terminals.
The dismantling process begins by removing the rear protective panel of the refrigerator. It is usually secured with several screws or latches. Once the panel is removed, you will see the compressor with a small plastic or metal casing attached to the bottom or side. It is inside this casing that what you are looking for is located starting relay along with a heat sensor.
☑️ Diagnostic tools
Carefully remove the casing, first disconnecting the wires if they interfere access. Pay attention to exactly how the relay is attached to the three terminals of the compressor. It can simply be put on top or fixed with a metal bracket. When removing, be careful not to damage the fragile ceramic insulators or the contacts themselves.
⚠️ Attention: Do not pull on the wires when removing the relay. Grab the body of the part and loosen it with light movements from side to side so as not to break the internal connections.
Visual inspection and initial check
Before picking up the multimeter, conduct a thorough visual inspection of the removed part. Often signs of a malfunction are visible to the naked eye. Carefully examine the case for melting, cracks or traces of burning. If the plastic has turned black or deformed, this is a sure sign that there has been a short circuit or overheating inside.
Shake the relay near your ear. If a rattling sound is heard inside, similar to the sound of broken glass, it means that the internal contact group is destroyed. In good condition, the part should not make any sounds when shaken. Also inspect the contacts for oxidation - a green or black coating indicates a poor connection and high contact resistance.
- 🕯️ The presence of traces of soot or carbon deposits on the contacts.
- 💥 Cracks or chips on the relay body.
- 🔊 Extraneous noise (bounce) when shaking.
- 🌡️ Melting of plastic fastening elements.
If no visual defects are detected, this does not guarantee serviceability. The internal winding of the coil could burn out, and the contacts could stick in the closed position. That is why the stage of instrumental diagnostics using measuring instruments is critical for making an accurate diagnosis.
Checking with a multimeter: step-by-step instructions
The most accurate result is obtained by checking electrical resistance using a multimeter. Switch the device to resistance measurement mode (Ohm) to a limit of 200 Ohm or continuity mode. First you need to determine the type of relay you have: they come with a coil (induction) and with a posistor (PTC). Induction relays have a movable core, and posistor relays have a special ceramic element.
To check the induction relay, find the contacts going to the coil. When testing these terminals, the device should show a certain resistance, usually in the range from 30 to 150 Ohms, depending on the model. If the device shows one (infinity), it means that a break has occurred in coil winding and the relay must be replaced. If the resistance is close to zero, there is an interturn short circuit.
Checking the posistor relay (PTC) is done in the same way. The resistance of a cold posistor is usually several tens of ohms. The main feature of such relays is that when heated, their resistance increases sharply, opening the circuit. It is difficult to check this effect with a multimeter in static conditions, so they often rely on the absence of an open circuit or short circuit.
| Test type | Normal reading | Fault | Action |
|---|---|---|---|
| Coil continuity | 30–150 Ohm | ∞ (infinity) or 0 | Replacement of relay |
| Contacts (closed) | 0 Ohm (Ringing) | There is resistance | Cleaning or replacement |
| Case insulation | ∞ (infinity) | Any value | Replacement (dangerous!) |
| Posistor (cold) | 10–50 Ohm | ∞ (infinity) | Replacing the relay |
Pay special attention to checking for insulation breakdown. Touch one probe to any contact and the other to the metal body of the relay. The device should not react (show infinity). If there is any resistance, use such a part strictly prohibitedas this may result in an electric shock when touching the refrigerator.
Analysis of the state of contacts and clamps
Even if the electrical parameters of the coil are normal, the problem may be hidden in the mechanical part. During operation, the contacts inside the relay are exposed to an electric arc, which leads to the formation of carbon deposits. This deposit increases resistance, causing heat and unstable operation. In some cases, the contacts can be carefully cleaned with fine sandpaper or a file, but this is a temporary measure.
Check the strength of the springs and the mobility of the mechanism. The spring should return the core or switch to its original position instantly. If the mechanism jams, the compressor rotor will not have time to gain speed, and the thermal protection will work. For induction relays it is also important to check whether the core moves freely inside the coil, whether it is pinched.
Inspect the connectors that fit onto the compressor terminals. They should fit tightly on the terminals and have no signs of oxidation. Poor contact in this place leads to sparking and melting of the plastic. If the connectors are loose or blackened, it is better to replace them or gently tighten them with pliers, having first cleaned the surface.
⚠️ Attention: Cleaning the contacts inside the relay is a temporary solution. The surface microrelief is disrupted, and sparking will resume. For reliable operation, a complete replacement of the unit is recommended.
Replacement and final assembly
If diagnostics confirm a malfunction, you must purchase a new part. Relays are selected strictly according to the markings indicated on the housing or according to the compressor model. There are no universal solutions here, since the starting characteristics of different engines differ. An incorrectly selected relay may not start the motor or, conversely, may not turn off the starting winding, which will lead to the engine burning out.
Installation of a new part is carried out in the reverse order of removal. Push the relay onto the three pins of the compressor as far as it will go. Make sure it fits evenly and tightly. Then connect the wires to the appropriate terminals, observing polarity if it is marked (although for most start relays polarity is not critical, for heat sensors it can be important).
After assembly, do not rush to close the back panel. Plug in the refrigerator and listen. The startup should be quiet, without loud clicks or buzzing. The compressor should pick up speed and run smoothly. If everything went well, you can fix the protective panel and operate the unit as usual.
Is it possible to replace the relay with an analogue from another manufacturer?
Yes, it is possible if the electrical characteristics and mounting dimensions match. It is important that the rated current and type of compressor (for example, for refrigerators with inverter control, the relays are different) match the original. The manufacturer's brand is secondary.
Why does a new relay burn out after a short time?
A common reason is a malfunction of the compressor itself (turn-to-turn short circuit of the windings) or problems with the voltage in the network. It is also possible that a relay has been selected with unsuitable starting current characteristics.
Is it dangerous to operate a refrigerator with a faulty relay?
Yes, it is dangerous. In addition to the risk of fire due to overheating of the wiring, there is the possibility of complete failure of the compressor, the replacement of which is not economically feasible. Voltage surges in the home network are also possible.
How much does a starting relay for a refrigerator cost?
The cost varies from 500 to 2000 rubles, depending on the model and manufacturer. Original parts for branded refrigerators (LG, Samsung, Bosch) are usually more expensive than universal analogs.