The situation when the refrigerator stops cooling always takes you by surprise. First of all, the owners begin to check the presence of electricity in the outlet, the integrity of the power cord and the temperature settings. However, if the unit hums, but does not cool, or is silent, despite the working backlight, most likely the problem lies in the heart of the system - the motor.
Diagnostics compressor requires care and compliance with safety precautions, since we are talking about working with electric current and refrigerant. Understanding how this unit works will help you save time and money by avoiding calling a technician for a basic check. In this article, we will look at how to determine a compressor malfunction in a refrigerator using simple tools and logical analysis of symptoms.
It is important to immediately note that single-phase motorinstalled in most household refrigerators may not start not only due to internal failure of the windings. Often the culprit is the start relay or thermostat. Therefore, before sinning on the motor itself, it is necessary to exclude external factors affecting its start and operation.
Primary visual diagnostics and sound analysis
The first stage of identifying the problem is to carefully listen to the operating (or trying to operate) unit. If you hear a characteristic hum that ends abruptly with a click, this indicates an attempt to start the engine. This sound often indicates that starting relay it is working, but the motor cannot gain speed.
In some cases, you can hear a quiet, barely noticeable hum without the rhythmic rumble characteristic of a working compressor. This may mean that current is flowing to the windings, but the rotor is blocked or jammed. It is also worth paying attention to the motor housing: if it heats up to the point where it is impossible to touch it with your hand in a few seconds, this is an alarming signal.
⚠️ Attention: If you hear a loud crackling sound or see sparking in the area of the back wall, immediately unplug the device from the power supply. Continuing operation in this condition can lead to a fire in the wiring or complete failure of the apartment's electrical network.
The absence of any sounds when the refrigerator is plugged in is also a diagnostic sign. If the light inside the chamber is on, then there is voltage and the problem is in the engine control circuit or in the electric motor itself. In this case, it is necessary to check thermostat the integrity of the supply wires.
To more accurately determine the nature of the malfunction, it is useful to know the main symptoms that indicate specific components. Below is a table to help classify the symptoms:
| Symptom | Probable cause | Required action |
|---|---|---|
| Humming and clicking after 2-3 seconds | Faulty start relay or compressor wedge | Checking the relay, measuring the resistance of the windings |
| The motor is hot, but is silent | Thermal protection relay or open circuit | Waiting for cooling, checking the thermal protection |
| Continuous operation without shutting down | Freon leakage or wear of the piston group | Checking pressure, searching for leaks |
| No sound when turned on | Thermostat malfunction or broken wire | Thermostat circuit check |
Checking the starting relay and thermal protection
Before drawing conclusions about a burnt-out motor, it is necessary to exclude faulty control components from the chain. Start relay responsible for supplying voltage to the starting winding at the time of start. If the contacts inside the relay are burnt or stuck, the engine will not be able to start, although electricity will flow to it.
To check the relay, it must be removed from the compressor. It is usually mounted on three contacts and secured with a bracket or latches. After carefully disconnecting the wires, inspect the inside of the device. The presence of carbon deposits, melted plastic or a characteristic burning smell clearly indicates the need to replace this element.
A tablet is often located next to the relay thermal protection. This element breaks the power circuit if the engine temperature exceeds permissible limits. If the bimetallic strip inside is deformed or the contacts are oxidized, the circuit will be open permanently. In a cold state, the resistance of a working thermal protection should be close to zero.
If a visual inspection does not reveal obvious defects, you can check with a multimeter. However, even a seemingly serviceable relay may not work under load. In such cases, the method of temporarily replacing it with a known-good analogue is often used to check the response of the compressor.
Diagnostics of electrical parameters with a multimeter
The most accurate way to determine the condition of the electric motor is to measure the resistance of the windings. To do this, you will need multimeterswitched to resistance measurement mode (Ohm). Before starting work, make sure that the refrigerator is disconnected from the mains and the residual charge has been removed from the capacitor.
Remove the protective casing from the back of the compressor to gain access to the contact group. Typically there are three terminals: common (C), starting (S) and working (R). Remove the start relay and thermal protection to clear the contacts. Now you need to ring pairs of contacts.
- 🔌 Common wire and working: Measure the resistance between the common contact and the working one. Typically it ranges from 10 to 30 Ohms, depending on the power of the motor.
- 🚀 Common wire and starting: The resistance between the common and starting contacts should be higher, usually in the range of 30-60 Ohms.
- ⚡ Working and starting: The total resistance between these two terminals should be equal to the sum of the two previous measurements.
If the device shows one (infinity), this means winding break. In such a situation, the compressor cannot be repaired and requires replacement. If the resistance is close to zero, this indicates an interturn short circuit. In both cases, further operation is impossible.
It is also important to check the breakdown on the housing. Switch the multimeter to dial mode (with sound) or resistance measurement to the maximum limit. Press one probe onto any motor contact, and with the other touch the unpainted part of the compressor housing or copper tube. The device should not make a sound, and the arrow (or numbers) should not react. Any reaction indicates that the winding is broken into the housingwhich is a critical and dangerous malfunction.
Mechanical malfunctions and jamming
Electrical serviceability of the windings does not guarantee the operation of the compressor. The mechanical part of the engine is also subject to wear and damage. The most common problem is jamming of the piston group. This can happen due to the exhaustion of the life of the rubbing parts, moisture entering the system or destruction of the valves.
Seizing can be determined if, when voltage is applied (for a short time!), the motor emits a dull hum, but the shaft does not turn. In some cases, experienced craftsmen try to “un-wedge” the compressor by applying increased voltage to the starting winding, but this method is risky and requires special equipment.
⚠️ Attention: Attempts at independent wedging without skills can lead to depressurization of the system or final destruction of the engine. If the motor hums and does not start after checking the relay, it most likely needs to be replaced.
Another mechanical problem is breakage or damage to the internal hangers. The compressor in the refrigerator is suspended on springs inside a sealed casing to dampen vibrations. If one of the springs breaks, a strong metallic clanging and knocking noise will be heard during operation. In this case, the engine can work, but the noise level makes operating the refrigerator impossible in a residential area.
Diagnostics of the condition of the internal valves is carried out by measuring the outlet pressure. If the compressor starts, but does not create the necessary vacuum at the inlet and pressure at the outlet, this indicates a leak in the valve group. You can check this by connecting the pressure gauge manifold to the service connection.
Analysis of operation in various modes
The behavior of the refrigerator in different operating modes can indicate the nature of the malfunction. For example, if the unit turns on, runs a short cycle and turns off before reaching temperature, this may indicate that the thermal protection relay has tripped due to overheating.
In fast freezing mode, the load on the compressor increases. If in this mode the engine begins to operate intermittently or often turns off, this indicates wear or insufficient efficiency of the cooling system of the engine itself (clogged condenser at the back of the refrigerator).
☑️ Diagnostics before calling a technician
It is also worth paying attention to the cyclical operation. A working refrigerator works in cycles: turned on, cooled, turned off. If you observe operation without stopping for several hours, and the temperature in the chambers does not drop below +10 degrees, this is a sure sign of loss of compressor performance or a refrigerant leak.
It is important to distinguish between the primary cause and effect. Often the compressor fails not on its own, but due to problems with other components. For example, a faulty thermostat may not give the command to turn off, causing the motor to wear out. Or a blockage in the capillary tube creates excess pressure that the engine cannot cope with.
When a compressor replacement is required
Replacing a compressor is a complex technological process that requires special equipment: a vacuum pump, a pressure gauge station and tools for soldering copper tubes. If diagnostics have confirmed a break in the windings, a breakdown in the housing or mechanical jamming, replacement becomes the only way out.
Replacement is also necessary if the compressor has lost performance due to wear of the valves, and it is impossible to restore it. In modern refrigerators with inverter compressors, diagnostics are more complicated, since they use electronic control, but the principles of checking the windings remain similar, although they have their own resistance nuances.
When deciding on repairs, it is important to consider economic feasibility. The cost of a new compressor and work to replace it (vacuuming, refilling with freon) can be a significant part of the cost of a new refrigerator. For older models (over 10-12 years old), it is often more profitable to purchase new equipment.
⚠️ Attention: Work on replacing the compressor and charging refrigerant should only be carried out by certified specialists. Independent soldering and refilling can lead to an explosive situation or damage to the ozone layer (depending on the type of freon).
Prevention and extension of service life
In order for the compressor of your refrigerator to serve for a long time, you must follow simple operating rules. First of all, ensure that the rear wall of the unit is well ventilated. Do not move the refrigerator close to the wall, leave a gap of at least 10 cm for free air circulation around the condenser.
Regular defrosting (for No Frost systems - cleaning the drainage hole) is also important. Excess ice on the evaporator causes the compressor to work longer and harder to reach the set temperature, which shortens its life. Keep the condenser grille at the back clean: dust and animal hair act as a heat insulator, impairing heat dissipation.
Myths about compressors
There is an opinion that frequently turning the refrigerator on and off is more harmful than constant operation. In fact, modern compressors are designed to last thousands of cycles. The most harmful thing for them is working in the “not turned on” mode or constant overheating due to poor ventilation.
Also avoid loading hot products into the chamber. A sharp increase in temperature inside the chamber causes the thermostat to command the motor to operate for a long time, which creates peak loads. Allow food to cool to room temperature before placing in the refrigerator.
Is it possible to restore a burnt-out compressor yourself?
Restoration It is impossible to repair a burnt out compressor at home. If a winding break or interturn short circuit occurs, the motor must be rewinded at the factory, which is not economically feasible. In case of jamming, professional “wedging” in a workshop sometimes helps, but this is a temporary measure.
Why does the new compressor get hotter than the old one?
Modern compressors often operate at higher housing temperatures, since the refrigerant passing through them cools the motor. If the temperature does not exceed 80-90 degrees and there are no signs of overheating (protection shutdown), this is normal. However, if it is hotter than usual, check the cleanliness of the condenser.
How often should you replace the compressor in a refrigerator?
The average lifespan of a compressor is 10-15 years. With careful operation and favorable conditions (stable voltage in the network, cleanliness, normal room temperature), it can last 20 years. This unit does not require scheduled replacement, only after a breakdown.
Does the type of freon affect the operation of the compressor?
Yes, it does. Compressors designed for freon R600a (isobutane) are structurally different from those running on R134a. They have lower performance and different oil. Filling with the wrong refrigerant or oil will lead to rapid failure of the compressor.