A sudden stop of the refrigerator is often accompanied by characteristic clicking noises coming from the engine compartment. Owners of household appliances notice that the unit is trying to start, the motor hums for a few seconds, and then there is a loud click and everything goes quiet. This is a classic picture of how start-protection relay performs its emergency function by breaking the electrical circuit.
It is impossible to ignore such symptoms, since frequent starting attempts can lead to serious consequences for the engine itself. Compressor is the heart of the refrigeration system installation, and its overheating or jamming of the piston group is fraught with expensive repairs or complete replacement of the unit. Understanding the reasons why the protection is triggered will help you quickly diagnose the problem and make the right decision.
In this article we will take a detailed look at the design of this small but critical element. You will find out why it turns off the power, how to distinguish a malfunction of the relay itself from problems with the motor, and whether it is possible to carry out repairs yourself without calling a technician.
The operating principle and design of a start-up protection relay
The start-up protection device is an electromechanical switch that controls the supply of voltage to the windings of the electric motor. When the refrigerator is turned on, the current passing through starting windingmust be high enough to create the necessary magnetic flux to start the rotor. As soon as the engine picks up operating speed, there is no need for the starting winding, and the relay should turn it off.
The protective function is implemented using a bimetallic plate that reacts to current or temperature. If the current in the circuit exceeds the rated values, the plate heats up and bends, opening the contacts. This prevents burning of winding insulation and failure of expensive compressor. Modern models often use posistor relays, where the role of a switch is performed by a ceramic element with varying resistance.
It is important to understand that the click you hear is not a breakdown, but the normal operation of the protection mechanism. However, if this process is repeated cyclically every few minutes, the system signals that it is impossible to start the engine normally. Relay contacts can burn out over time, which increases resistance and disrupts the operation of the entire circuit.
⚠️ Attention: Before any manipulations with the electrical components of the refrigerator, be sure to disconnect the appliance from networks. Residual voltage can be stored in capacitors, and careless handling of live wires is dangerous.
Structurally, the device can be made in the form of a separate unit or integrated into the overall control circuit, especially in inverter models. In classic refrigerators Indesit or Atlant most often there are separate hanging relays that are easy to dismantle for testing.
What is the difference between posistor relays and electromagnetic ones?
Posistor relays do not have moving mechanical parts to break the starting circuit windings They use a ceramic element (posistor), which, when heated by current, sharply increases its resistance, essentially turning off the winding. They are considered more reliable, but are sensitive to power surges in the network.
Main reasons for frequent protection operation
There are several key factors leading to emergency shutdown of the motor. Most often, the problem lies in mechanical jamming or electrical breakdown. If compressor cannot turn due to a jammed piston, the current in the windings increases sharply, and the protection operates almost instantly.
Another common reason is wear of the starting device itself. Over time, the contacts inside the case oxidize or burn, resulting in a poor connection. As a result, the engine does not receive enough impulse to start, it hums, but does not start, which causes the bimetallic plate to heat up.
Problems with the power supply cannot be ruled out. Low voltage in the network does not allow the engine to develop the necessary power to start. In such conditions starting winding works longer than expected, the current does not drop, and the relay is forced to break the circuit to avoid overheating.
It is also worth paying attention to the condition of the wiring and capacitor. If working capacitor lost capacity, the phase shift of the current is disrupted and the motor operates inefficiently, consuming increased current. This is also a signal for the protection system to stop.
Fault diagnosis: step-by-step instructions
To accurately determine the cause, it is necessary to conduct a visual inspection and instrumental testing. The first step is to remove the back panel of the refrigerator and gain access to the compressor compartment. Make sure that the device has cooled down, as after trying to start motor housing it may be very hot.
Remove the relay from the compressor contacts. It is usually secured with a bracket or latches. Carefully inspect the inside: the presence of soot, melted plastic or a burning smell clearly indicates a malfunction. If external defects are not found, you will need a multimeter to check the continuity of the circuit.
☑️ Primary diagnostic algorithm
When checking with a multimeter, you must set the resistance measurement mode. The probes are applied to the input and output contacts of the relay. In good condition, the resistance should be close to zero (for closed contacts) or infinity (for open ones), depending on the type of device and its position. For posistor relays, it is important to let them cool for 10-15 minutes before checking, since when hot they do not conduct current.
Pay special attention to checking the windings of the compressor itself. Measure the resistance between the contacts on the motor housing. Typically it ranges from 10 to 30 Ohms for the starting winding and a little less for the working winding. If the multimeter shows one (open) or zero (short circuit), the problem lies in the motor itself, and the relay only reacts to an accident.
⚠️ Attention: When testing the windings, do not touch the metal probes with your hands, so as not to introduce an error in the measurements. Also make sure that there is no ground fault between the compressor housing and the contacts.
Table of symptoms and probable faults
Analysis of the behavior of the refrigerator allows you to narrow down the troubleshooting area. Below is a table that will help you compare the observed symptoms with the most likely causes. This will make it easier to decide on further actions.
| Symptom | Probable cause | Required action |
|---|---|---|
| Buzzing for 5-10 seconds, then clicking and silence | Faulty start relay or jammed compressor | Replacing the relay, checking the compressor |
| The refrigerator hums constantly without turning off | Freon leak or thermostat malfunction | Search for leaks, replace the thermostat |
| The relay clicks immediately when plugged in | Short circuit in the windings or breakdown of the relay | Urgent electrical diagnostics |
| A hum is heard, but there is no start, the relay is cold | Open circuit or capacitor malfunction | Replace the capacitor, check the circuit |
Using this data, you can determine with a high degree of probability whether a simple replacement of a consumable or a major repair is required. Remember that symptoms different breakdowns may be similar, so a comprehensive check is always preferable.
Replacing the start-up protection relay with your own hands
If diagnostics show that the problem is in the relay, replacing it is a standard procedure available to a home handyman. The main condition is to select an exact copy of the device, since they differ in power, connection type and contact orientation. The relay model is usually indicated on the case or in the technical documentation of the refrigerator.
The replacement process begins by disconnecting the unit from the power supply. Remove the old device, having previously photographed the wiring diagram so as not to confuse them when installing a new element. Carefully disconnect the terminals, trying not to damage the insulation of the wires, which could become brittle due to heating.
Install a new one relay to the compressor contacts, observing the correct orientation (usually the arrow on the housing indicates the “Up” or “Up” direction). Connect the wires according to the photo or color marking you took earlier. Securely secure the device with a fixing bracket or frame.
After assembly, turn on the refrigerator and listen. The startup should go smoothly, without a long buzz. If the motor starts and turns off after a while when it reaches temperature, the repair can be considered successful. Otherwise, if the symptoms recur, the problem may be deeper and concern the compressor itself. Successful replacement of the relay is possible only if the characteristics of the new device exactly match the original. Using analogues with other parameters may lead to repeated breakdown. compressor.
Prevention and operating rules
To extend the service life of the start-up relay and compressor, it is important to ensure correct operating conditions for the refrigerator. First of all, this concerns the temperature regime in the room. Operating at extremely high or low temperatures increases the load on the engine and starting system.
Regular cleaning of the condenser (the grill at the back of the refrigerator) of dust and animal hair is also necessary. A heat exchanger clogged with dust leads to overheating of the refrigerant and increased pressure in the system, which makes it difficult to start the compressor and triggers the protection.
Avoid opening the door frequently and setting the temperature too low unless necessary. Sudden changes in the load on the motor reduce the life of its components. It is also recommended to use a voltage stabilizer if your network experiences frequent fluctuations.
⚠️ Attention: Specifications and service requirements may vary depending on the manufacturer and model year. Always check the official user manual for your specific device so as not to violate the terms of the warranty.
Following these simple rules will help avoid premature failure of expensive components. Remember that prevention is always cheaper than major repairs or buying new equipment.
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the engine by applying voltage directly to the working winding, but this is strictly not recommended. Without protection, the motor will burn out in a matter of minutes in case of any jamming or current surge, which will lead to irreversible consequences.
Frequently asked questions (FAQ)
Why does the relay click, but the refrigerator does not freeze?
This means that the compressor is trying to start, but cannot turn around. Most often, the reason is jamming of the piston group due to lack of oil or mechanical damage, or a malfunction of the starting device itself, which does not supply the required impulse to the starting winding.
Is it possible to repair a burnt out relay?
In most cases, repairing a relay is impractical. Inside there are calibrated elements (bimetallic plate, springs, posistor), the parameters of which are violated when overheated. An attempt to clean the contacts gives only a temporary effect, after which the device will fail again.
How can you tell whether the compressor or relay has burned out?
You need to ring the compressor windings with a multimeter. If the resistance between the motor contacts is normal (10-30 Ohms) and there is no breakdown to the housing, and the relay does not close the circuit or has traces of burning, the problem is in the relay. If the windings show an open or short circuit, the compressor is faulty.
How much does it cost to replace the start relay?
The cost of the device itself varies from 500 to 2000 rubles, depending on the model of the refrigerator and the manufacturer of the spare part. The work of a replacement technician usually costs from 1000 to 2500 rubles, although the process takes no more than 20 minutes.