A sudden stop in the operation of refrigeration equipment often takes people by surprise, creating a risk of food spoilage. The first sign of a malfunction is usually an increase in temperature inside the chambers or a complete absence of the characteristic hum of a running motor. However, the absence of sound does not always mean a breakdown of the engine itself, since the problem may be hidden in the control system or the start relay.
Before calling a technician, it is important to conduct an initial diagnosis to understand the scale of the problem. Compressor is the heart of the refrigeration circuit, and its serviceability directly affects the ability of the unit to produce cold. In this article, we will analyze in detail the testing methods available at home and will help you make the right decision on further repairs.
Understanding the principle of operation will allow you to avoid unnecessary expenses and correctly formulate the task for a specialist if independent repairs turn out to be impossible. We will look at both simple sound assessment methods and more complex diagnostic methods using measuring instruments.
Visual inspection and initial condition assessment
The diagnosis should begin with an external inspection of the back of the refrigerator, where the motor-compressor is located. Carefully inspect the housing of the device for visible damage, dents or traces of soot, which may indicate overheating or a short circuit. It is also worth checking the integrity of the tubes coming from the unit, since a refrigerant leak can be visually noticeable through oily spots.
Pay attention to the temperature indicators, if they are on the front panel. Modern models are often equipped with a self-diagnosis system that displays error codes when the compressor malfunctions. The absence of an indication or flashing lights may be the first signal of problems with the electrical circuit or sensors.
It is also important to check whether the light inside the camera is on when the door is open. If there is lighting, it means that electricity is supplied to the apartment, and the problem is localized in the refrigerator itself. If there is no light, check the socket and power cord, since sometimes the reason is trivial - lack of voltage in the network.
⚠️ Attention: Before any visual inspection of the internal elements, be sure to disconnect the refrigerator from the power supply. Working with live electrical appliances without appropriate qualifications is life-threatening.
Pay special attention to the condition of the starting relay, which is mounted on the side of the compressor. If traces of melting are visible on it or a burning smell is felt, there is a high probability that this particular element has failed, preventing the engine from starting.
Analysis of sound signals of a working device
Sound is the most accessible indicator of the condition of the equipment. A working one compressor emits a smooth, monotonous low-frequency hum. Any deviations from this sound background require close attention and decoding, as they may indicate specific mechanical or electrical faults.
You can often hear clicks that are repeated at certain intervals. This may indicate an attempt to start the engine, which immediately stalls due to the activation of a thermal relay or a malfunction of the starting winding. Also an alarming signal is the complete silence of the unit when the power is on.
For a more accurate diagnosis, let's make a list of characteristic sounds and their possible meaning:
- 🔊 Smooth, quiet hum - normal operation, the compressor is working and cools the chamber.
- 🔨 Loud knocking or clanging when starting - possible wear of the piston group or problems with fastening the shock absorbers.
- ⚡ Frequent clicks without starting - a malfunction of the starting relay or an interturn short circuit in the windings.
- 🤫 Complete absence of sound after switching on - open power circuit, burnt out motor or thermostat malfunction.
If you hear the motor humming for a few seconds, and then there is a click and silence, this is a classic symptom of a “wedge” effect or an insulation breakdown. In such cases, further attempts to turn on can finally finish off the unit.
Checking the thermostat and start relay
Before sinning on the motor itself, it is necessary to exclude malfunctions of the controls. Thermoregulator (Thermostat) is responsible for supplying voltage to the compressor when a certain temperature is reached. If it is faulty, the start signal simply will not be received, and the refrigerator will be silent, even if it is working properly.
To check the thermostat in some models, you can close the contacts of the wires going to it, but this requires caution. A safer method is to remove it from the circuit temporarily by connecting the wires directly and see if the motor starts. If startup occurs, then the problem is in the temperature sensor.
The start relay is another critical unit. It supplies an impulse to the starting winding, helping the rotor to spin. If the relay is stuck or burnt out, the compressor will not be able to overcome the initial resistance and start. Often it is enough to simply replace this part to revive the refrigerator.
How to remove the start relay yourself
To remove the relay, you need to disconnect the refrigerator from the mains, remove the back protective panel, carefully disconnect the wires and remove the plastic casing from the side of the compressor. The relay is usually simply put on the contacts and secured with a bracket or latches.
When inspecting the relay, shake it near your ear: if a ringing or knocking sound is heard inside, it means that the internal mechanics are broken and the part requires replacement. Visually, the contacts inside the relay should not have traces of carbon deposits or oxidation.
Diagnostics using a multimeter
The most accurate way to check is to use multimeter. This device will allow you to measure the resistance of the windings and verify the integrity of the electrical circuit. To carry out the work, you will need access to the contact group of the compressor, from where the starting relay is usually removed.
First you need to find the common contact and the contacts of the starting and working windings. The resistance between the common contact and the working contact should be minimal, and between the common and starting contacts it should be average. The sum of these two values should equal the resistance between the starting and operating contacts.
☑️ Checking the compressor with a multimeter
Below is a table of approximate resistance values for various types of compressors. Please remember that the exact data may vary depending on the model and manufacturer.
| Measurement type | Normal value (Ohm) | Fault symptom |
|---|---|---|
| Working winding | 15 – 35 Ohm | Open circuit or short circuit |
| Start winding | 25 - 50 Ohm | Open circuit or short circuit |
| Case and any contact | Infinity (∞) | Breakdown to housing (dangerous!) |
| Thermal relay | 0 Ohm (closed) | Open circuit (relay burned out) |
If the device shows infinity on the windings, it means that the wire inside the engine has broken, and such a compressor cannot be repaired. If the resistance is close to zero, there is a short circuit in the turns.
It is also worth checking the breakdown on the housing. One multimeter probe is applied to the cleaned area on the compressor housing, and the other to any of the contacts. The device should show infinity. Any other values indicate a violation of the insulation, which makes the operation of the refrigerator dangerous.
Assessment of pressure and operation of the discharge system
If the electrical part is in order, but cold is not produced, the problem may be in the mechanical part or a freon leak. Pumping capacity the compressor is checked by the outlet pressure. For this, craftsmen use a pressure gauge station, connecting to the service fitting.
At home, you can carry out a rough check: with the compressor running, place your finger near the outlet of the condenser (being careful, it may be hot there). You should feel confident air pressure. If the air comes out weakly or not at all, it is possible that the compressor does not “hold” the valve.
The temperature of the tubes may also indicate problems with pressure. During normal operation, one tube (compressor outlet) should be hot and the other (evaporator inlet) should be cold. If the tubes are the same temperature or are covered with frost only at the outlet, this is a sign of a problem with refrigerant circulation.
Refrigerant leakage is a common reason why the compressor runs constantly, but does not cool. In this case, the motor is working fine, it just drives empty space. You can determine a leak by oily stains on the tubes or by using a soap solution that will begin to bubble at the site of damage.
Typical faults and methods for eliminating them
We will systematize the most common problems faced by refrigerator owners. Understanding the nature of the malfunction will help you choose the right repair strategy or decide to replace the unit.
- 🛑 The compressor does not turn on: Check the thermostat, start relay and the integrity of the supply wires. A winding break is possible.
- 🔥 Intense heating of the housing: It may indicate an interturn short circuit or operation in the “dry running” mode when freon leaks.
- ❄️ Works, but does not freeze: Leakage refrigerant, clogged capillary tube or loss of compression (piston wear).
- 🔊 Loud noise and vibration: Wear of bearings, loose fastenings or damage to shock absorbers.
It is important to note that replacing a compressor is a complex technological process that requires evacuation of the system and charging with freon. It is impossible to perform these operations independently without special equipment.
⚠️ Attention: It is prohibited to open the sealed circuit of the cooling system without a license and equipment. Refrigerants can be hazardous to health, and incorrect filling will lead to rapid failure of the new compressor.
If the diagnostics showed a malfunction of the motor itself, the most rational solution would be to call a specialist to replace the unit. Repairing old compressors by rewinding the windings at home is impractical and not economically justified.
When choosing a new compressor, be sure to pay attention to its power and type of refrigerant, as they must comply with the parameters your refrigerator model. Using an unsuitable analogue can lead to unstable operation.
Frequently asked questions (FAQ)
Why does the compressor hum, but does not start, and then clicks after a while?
This is a classic sign of a faulty start relay or jammed piston group. The relay tries to start the motor, the current increases, the thermal protection (click) is triggered, and the cycle repeats. Replacement of the relay or diagnostics of the compressor with a “wedge” is required.
Is it possible to operate the refrigerator if the compressor operates intermittently?
Short-term breaks are a normal operating cycle controlled by a thermostat. However, if the operating intervals are too short or, conversely, the refrigerator does not turn on for a long time, losing cold, this indicates a malfunction of the thermostat or a freon leak.
How to distinguish compressor noise from fan noise?
Compressor noise is usually low-frequency, vibrational. The fan noise (if the No Frost model has it) is higher frequency, similar to a hum or whistle. To check, you can carefully (without touching the blades!) stop the fan with your hand - if the noise disappears, the problem is there.
How long does a compressor in a refrigerator last on average?
The average service life of a modern compressor is from 7 to 10 years. However, with careful operation and stable mains voltage, it can last 15 years or more. Inverter models, as a rule, have a longer life due to a soft start.