Sudden silence in the kitchen or, conversely, an unusually loud hum may be the first signals that your kitchen has ceased to perform its main function. When food begins to deteriorate and frost disappears on the walls of the chambers, the first thing that arises is a suspicion that the main unit—the motor—has failed. It is this that circulates the refrigerant, creating the necessary cold. You can understand whether the problem really lies in this unit by a number of indirect signs, without immediately resorting to complex tools. refrigerator stopped performing its main function. When food begins to deteriorate and frost disappears on the walls of the chambers, the first thing that arises is a suspicion that the main unit—the motor—has failed. It is this that circulates the refrigerant, creating the necessary cold. You can understand whether the problem really lies in this unit by a number of indirect signs, without immediately resorting to complex tools.
However, relying only on hearing or the absence of vibration of the case is not always reliable. Modern models can operate very quietly, and in some cases the engine hums, but does not pump freon due to internal valve failure. Therefore, it is important to know the sequence of actions for the initial check, which will allow you to weed out simple faults, such as an electronic failure or an open circuit, from serious mechanical damage that requires replacement of the unit.
In this article we will analyze all the available diagnostic methods, from simple visual inspection to the use of measuring instruments. You will learn to distinguish between the symptoms of a breakdown compressor from problems with the thermostat or a gas leak. This knowledge will help you make an informed decision: call a technician for complex repairs or try to fix the problem yourself if it lies in the starting relay or wiring.
Primary diagnosis: sound and tactile signs
The easiest way to perform a primary check is to carefully listen to the operating unit. A serviceable engine emits a smooth, monotonous low-frequency hum. If you hear a clicking sound, an intermittent hum, or the engine tries to start and immediately stalls, this is a sure sign of an electrical problem or a mechanical jam. Often such sounds indicate that starting relay the rotor cannot start, or the motor itself has become “stuck.”
In addition to sound, an important indicator is the temperature of the housing. When the compressor is running, its surface (usually the black metal barrel at the bottom at the back) should heat up. If the motor hums but remains cold, the winding may be broken or the piston group may be jammed. A working unit should be hot to the touch, but not scalding, with a temperature of about 50-60 degrees Celsius.
⚠️ Attention: Before touching the metal parts inside the rear niche of the refrigerator, make sure that the device is unplugged. Residual voltage or damaged insulation can lead to electric shock.
It is also worth paying attention to the cyclic operation. Normal mode involves periodic switching on and off. If unit works non-stop for days, trying to gain temperature, this indicates a loss of productivity. In such cases, the compressor may be electrically functional, but mechanically worn out, which does not allow it to create sufficient pressure in the system.
For a more accurate understanding of the symptoms, consider the main symptoms in the comparative table:
| Symptom | Probable reason | Nature of the malfunction |
|---|---|---|
| The motor hums for 5-10 seconds and clicks | Faulty starting relay | Electric, repair possible |
| Complete silence, light yes | Open circuit or burned out motor | Electric, needs replacement |
| Humming constantly, no cold | Freon leak or wear | Mechanical, complex repair |
| Strong vibration and knocking | Broken shock absorbers or valves | Mechanical, replacement of the unit |
Visual inspection and checking the electrical circuit
Before disassembling the unit, it is necessary to exclude external factors. Make sure that the refrigerator is tightly plugged into the outlet and that there is power. Often the problem lies in oxidized plug contacts or damaged power cord. If everything is in order with the power supply, you should proceed to inspect the rear of the unit where the motor is located.
Remove the protective cardboard or metal cover covering the compressor area. Visually assess the condition of the wires going to terminal the engine. There should be no traces of melting, burning or the characteristic smell of burnt plastic. Black deposits on the contacts indicate overheating and a poor connection, which could lead to failure of the control electronics.
Pay special attention to the start relay and thermal relay, which are usually placed directly on the compressor contacts. Carefully remove the plastic relay box. If you see blackened contacts inside or smell a burning smell, there is a high probability that this particular element is blocking startup. In some cases, the relay can be replaced, and the motor will start working again without replacing the most expensive component.
☑️ Diagnostics before disassembly
If no visual defects are found, proceed to a deeper check. It is important to understand that even intact wires can hide a break inside the insulation. Therefore, move the wiring in the places of bends with the device turned on (carefully!) to see if sparking appears or if the motor will not start.
Using a multimeter to check the windings
The most accurate method of diagnosing the electrical part is to “test” the windings using a multimeter. This device will allow you to determine the integrity of the circuit and the absence of a short circuit to the housing. To carry out the procedure, you will need to switch the tester to the resistance measurement mode (Ohm) with a limit of up to 200 Ohm.
First you need to gain access to the motor contacts. Remove the starting and protective relay from the compressor terminals. You will see three pins forming a triangle. Two of them are closer to each other - these are the starting and working windings, the third, located separately, is the general output. Usually the circuit is marked, but it is better to rely on measurements.
Attach the multimeter probes to the pairs of contacts. The resistance between the common and working terminals should be approximately 10-30 Ohms, and between the common and starting terminals it should be slightly higher, about 20-40 Ohms. The sum of these values should approximately equal the resistance between the start and run contacts. If the device shows infinity (one on the screen), it means there is a break in the winding break.
⚠️ Attention: Never check the resistance of the windings while the device is connected to the mains. This will lead to instant failure of the multimeter and can be life-threatening.
It is also critically important to check the breakdown on the case. Apply one probe to any of the three contacts, and the second to the metal tube of the compressor or the refrigerator body, which has been stripped of paint. The device should show infinity. If the tester beeps or shows any resistance value, it means that the insulation is broken and the motor “breaks through” to ground. Using such a unit is strictly prohibited.
Nuances of resistance measurement
When measuring winding resistance, it is important to consider that the readings may “float” a little in the first seconds due to heating of the probes. The battery charge in the multimeter also affects the accuracy. If the readings are close to the limit values, let the engine cool completely and repeat the measurement after 15-20 minutes.
Checking the starting relay and thermal protection
Often the compressor itself is working, but cannot start due to a faulty starting relay. This small block is responsible for supplying an impulse to the starting winding at the moment of start. If the relay is “stuck” in the closed state, the winding may burn out. If it does not close, the engine will only hum, trying to turn over.
You can check the relay by shaking it vigorously near your ear. If you hear the ringing of broken parts or knocking inside, it means the mechanism is destroyed. Electromagnetic relays should not make rattling sounds when at rest. Also inspect the internal chamber of the relay for melting and carbon deposits on the contacts.
The thermal relay (thermal protection) also plays an important role. It opens the circuit when the windings overheat. You can check its integrity with a multimeter in dial mode. The resistance of a working thermocouple should be close to zero. If the circuit does not ring, the protection has tripped or burned out, blocking the supply of voltage to the engine.
Some models of refrigerators, especially old ones, use capacitors to facilitate starting. Checking them requires a special capacity tester, but visually they often reveal themselves by swelling of the body or leakage of electrolyte. Replacing these elements is cheaper than repairing the compressor itself compressor.
Analysis of pressure and performance (for advanced)
If the electrical part is normal, but there is no cold, the problem may lie in the mechanical inability to create pressure. To check this parameter, craftsmen use a pressure gauge station. A pressure gauge is installed on the discharge pipe (outlet tube), and the pressure is measured at startup.
A working piston or linear compressor should quickly (in 30-60 seconds) create a pressure in the system of about 6-8 atmospheres (depending on the model and type of refrigerant). If the pressure gauge needle barely creeps or stands still, it means that the valves inside the head are worn out or stuck. In this case, the engine runs idle.
There is a popular, but crude method of testing “by finger”. With the engine running, place your finger on the hole in the discharge tube (after disconnecting the system). You should feel a strong, rhythmic flow of air that is difficult to block with your finger. A weak whiff indicates a loss of compression.
It is important to note that modern inverter models refrigerators are more difficult to diagnose in this way, since they smoothly regulate speed. To check them, you often need to connect a special test bench that simulates the operation of the control board.
Specifics of diagnostics of inverter compressors
Owners of modern models with the system No Frost and inverter control should know that their technology is designed differently. There is no usual cyclic on and off. The engine runs constantly, changing speed. Therefore, the absence of characteristic relay clicks is the norm for them.
Diagnostics of inverter motors is impossible by simply testing the windings, since they have a different connection diagram and often contain built-in electronics. The resistance of their windings can be very low (less than 10 ohms) or, conversely, high, which is not a sign of a breakdown without knowledge of the specification data of the specific model.
The main sign of a malfunction of the inverter unit or the motor itself is an error code on the refrigerator display or a specific signal (flashing indicators). An attempt to start such a motor directly, bypassing the control board, will lead to its immediate combustion. This requires professional equipment to read errors.
⚠️ Attention: Inverter compressors are sensitive to voltage changes. Before replacing such a unit, be sure to make sure that the electrical network in your home is stable; you may need to install a stabilizer.
If you are faced with an inverter model and do not have experience working with electronics, the best solution would be to contact a service center. Independent manipulation of control boards often leads to higher repair costs.
Frequently asked questions (FAQ)
Can a compressor burn out due to a power surge?
Yes, a sharp surge in voltage in the network is one of the most common causes of failure of both the starting relay and the start relay. and the motor windings themselves. The protection does not always have time to operate, and an insulation breakdown or melting of the contacts occurs.
A click is heard, but the refrigerator does not turn on - is this dangerous?
This indicates that the relay is trying to start the motor, but cannot. Long-term operation in this mode (frequent clicks every few minutes) is dangerous due to overheating of the windings and can lead to complete combustion of the compressor. It is better to turn off the device until the reasons are determined.
How to distinguish a compressor breakdown from a freon leak?
When there is a freon leak, the compressor often works continuously, trying to gain temperature, but there is no cold. If the compressor itself breaks down, it either does not start at all, or starts for a short time, followed by a click and shuts down.
Is it worth replacing the compressor on an old refrigerator?
The economic feasibility of replacement depends on the age of the equipment. If the refrigerator is more than 10-12 years old, the cost of a new compressor and work to replace it (including refilling with freon) can be 70-80% of the price of a new device. In such cases, it is often more profitable to buy new equipment.
Why may a new compressor not start?
The reason may be incorrect connection of wires to the terminals, a malfunction of the starting relay (it is better to change it in tandem with the motor), the absence of a starting capacitor (if it is provided for in the circuit) or blocking of the control board due to sensor errors.