A sudden stop of the refrigeration chamber is always stressful, because food and the usual way of life are at risk. When the device stops freezing, the first thing owners do is start looking for ways to check whether the refrigerator compressor is working or not in order to understand the scale of the problem. Often the cause is the motor-compressor, which is the heart of the entire system, but premature panic is not necessary, since the fault may be hidden in other components.
Modern diagnostics make it possible to identify a breakdown even without calling a technician, if you have minimal technical skills and a basic set of tools. In this article we will analyze in detail the algorithm of actions that will help determine the condition electric motor, check the integrity of the windings and evaluate the performance of the trigger mechanism. Video materials built into the logic of the description will help visually consolidate theoretical knowledge.
Do not forget that any work with electrical appliances requires strict adherence to safety precautions. Before starting any manipulations, be sure to disconnect the unit from the electrical network and let it stand in the off state for at least 15-20 minutes. This time is necessary to discharge the capacitors and stabilize the refrigerant pressure in the system, which is critical for correct diagnosis.
Primary visual and acoustic diagnostics
Before picking up measuring instruments, you should conduct a careful external inspection and listening to the operating (or trying to start) unit. Often, characteristic sounds or their absence can tell more about the condition motor-compressor than complex measurements. Plug in the refrigerator and listen: if you hear a quiet hum that ends abruptly with a click, this may indicate an attempt to start and subsequent activation of the thermal protection relay.
The absence of any sounds when plugged into the socket is also an alarming signal. This could mean an open circuit, a thermostat malfunction, or a complete failure of the engine's electrical components. If the motor hums continuously, but no cold is produced, the mechanical part may have jammed or the piston group has lost compression.
⚠️ Attention: If you hear a loud metallic knock, grinding or squealing immediately after turning on, immediately turn off the power to the device. Further operation in this mode can lead to the final destruction of internal components and costly repairs.
Visually inspect the rear of the unit where the compressor unit is located. Look for traces of soot, melted insulation, or oily smudges, which may indicate a breakdown or depressurization. The presence of black carbon deposits on the tubes or motor housing often indicates an interturn short circuit that has already occurred.
Checking the start relay and thermostat
Often the question of how to check the refrigerator compressor is decided long before the motor itself. In 40% of cases, the cause of the failure is not the engine itself, but the starting relay or thermostat. The relay is responsible for supplying voltage to the starting winding at the time of start, and if its contacts are burnt or the mechanical rod is jammed, the motor will not start.
To check the relay, it must be carefully removed from the compressor contacts. Depending on the design, this may be a device with an inductance coil or a posistor. Posistor relays are tested for resistance: when cold it should be low, and when heated it should go to infinity. Relays with a coil are checked for the absence of an open circuit and the ease of movement of the core.
How to distinguish different types of relays?
Relays with a coil usually have a vertical installation and a heavy case, with a copper winding visible inside. PTC relays are often made in a horizontal plastic case, inside there is a ceramic element (posistor) and a bimetallic plate.
The temperature regulator also plays a key role in the power circuit. If its contacts are open, the voltage simply will not reach the motor. You can check it by short-circuiting the input and output wires (after disconnecting the refrigerator from the network!). If, after closing and connecting to the network, the compressor started working, then the problem was in the thermostat, which requires replacement.
When removing the relay, be extremely careful with the contact group. Oxidized contacts can be carefully cleaned with fine sandpaper, but if the plastic has melted, the part must only be replaced. Using a faulty relay can lead to overload of the motor windings and their combustion.
Instrumental testing of the windings with a multimeter
The most accurate diagnostic method is to test the windings using a multimeter. To do this, you will need to remove the protective casing from the compressor and gain access to the contact group. Usually there are three terminals: two upper and one lower (or three in a row), which correspond to the starting, working winding and common wire.
Switch the multimeter to resistance measurement mode (2 kOhm). First, check for a short to the housing: touch one probe to any contact, and the other to the stripped metal part of the housing (where there is no paint). If the device shows one or infinity, the insulation is intact. The appearance of any numbers indicates a breakdown, which makes further operation dangerous.
Next, you need to find the common wire and measure the resistance between the terminals. Typically, the resistance between the common wire and the working winding is 15-30 Ohms, and between the common and starting windings - 30-50 Ohms. The sum of these two values should approximately equal the resistance between the starting and operating terminals. If you see zero, there is a short circuit, if infinity there is a break.
☑️ Algorithm for testing with a multimeter
It is important to understand that different models of refrigerators, such as Indesit, Atlant or Bosch, have different resistance ratings. However, the principle remains the same: the working winding always has less resistance (thicker wire) than the starting winding. A violation of this proportion indicates an interturn short circuit.
Analysis of current characteristics and pressure
If the electrical part of the motor is in order, but the refrigerator does not freeze, it is necessary to check its mechanical ability to create pressure. For this, a special device is used - a compressor tester, which is a pressure gauge with a set of fittings. It is connected to the discharge fitting instead of the condenser grille.
With a working mechanical part, the compressor should create a pressure of 3-4 atmospheres (or the corresponding value in bar/psi) in a few seconds. If the pressure gauge needle barely creeps or stands still, it means there has been a loss of compression. This may be caused by broken valves, wear of the piston group, or, in the worst case, a break in the connecting rod inside the sealed casing.
| Type of malfunction | Pressure gauge readings | Sound background | Probability repair |
|---|---|---|---|
| Normal | 3.5 - 4.5 atm | Uniform humming | Not required |
| Clogged capillary | Sharp jump to 6+ atm | Strained hum | Cleaning the system |
| Valve wear | Less than 2 atm | Quiet operation | Replacing the compressor |
| Broken connecting rod | 0 atm | Knocking, lack of pressure | Replacing the compressor |
It is also important to check the current consumption using current clamps. If the motor consumes a current significantly higher than the rated current (indicated on the nameplate), but does not start or runs overheated, this is a sure sign of mechanical jamming or a strong inter-turn short circuit. In this case, further work will lead to burning of the wiring in the apartment.
Frequent errors during self-diagnosis
Many home craftsmen, trying to save on calling a specialist, make critical mistakes that turn a simple repair into a complete replacement of the unit. One of the most common mistakes is an attempt to start the compressor directly, bypassing the thermal relay and start protection device. This can lead to instant burning of the starting winding, since it is not designed for long-term operation.
Another mistake is ignoring the state of the capacitor (if it is in the circuit) or incorrectly assessing the insulation resistance. Some users believe that if the motor is humming, it means it is alive. However, a humming noise may mean that the rotor is stuck in its extreme position, and an attempt to forcibly spin the shaft indiscriminately can damage the bearings.
⚠️ Attention: Never cut through the refrigeration circuit pipes if there is still pressure in the system. The refrigerant is under pressure and sudden release of oil or gas may cause damage to eyes or skin. First, you need to carefully file the tube and vent the gas in a well-ventilated area.
Also, do not rely only on visual inspection of the wires. Microcracks in the insulation inside the windings are not visible to the eye, but lead to breakdowns under load. That is why a comprehensive check, including both visual and instrumental control, is mandatory.
Replacement or repair: economic feasibility
After we managed to check the refrigerator compressor and identify it inoperability, the question arises about further actions. Repair of hermetic compressors in domestic conditions is impossible due to the need for specialized equipment for welding and vacuuming. The only option is to replace the unit with a new or refurbished one.
The cost of a new compressor, including replacement work, refilling with freon and replacing the filter-drier, often amounts to 50-70% of the price of a new refrigerator. Therefore, if your unit is more than 10 years old, it makes sense to consider purchasing new equipment that will be more energy efficient and quieter.
However, if the refrigerator is premium or just new, replacing the motor is completely justified. It is important to choose an analogue with identical characteristics: power, refrigerant (R134a, R600a) and overall dimensions. Using an unsuitable motor will lead to unstable operation and rapid failure of the entire system.
When making a decision, also take into account the condition of the thermal insulation and door seals. If they are worn out, even a new compressor will work with overload, trying to compensate for heat inflows, which will again lead to breakdown.
FAQ: Frequently Asked Questions
Is it possible to restore a jammed compressor?
There is a method of “wedging” by applying increased voltage or mechanical impact, but its effectiveness is extremely low (less than 10%). In most cases, this is only a temporary measure that finally kills the engine. It is more reliable and safer to replace.
Why does the new compressor get hotter than the old one?
Modern motors often operate at higher temperatures due to the use of new refrigerants (for example, R600a) and increased energy efficiency. If the case temperature does not exceed 80-90 degrees and there is an on-off cycle, this may be the norm.
How long should the compressor operate normally?
The operating time depends on the chamber load, ambient temperature and thermostat settings. Typically the operating cycle ranges from 10 to 30 minutes, followed by a pause. Constant operation without shutting down indicates a freon leak or a malfunction of the thermostat.
Is it dangerous to change the compressor yourself?
Yes, it is dangerous. In addition to the risk of electric shock, there is the danger of working with flammable gases (isobutane) and high pressure. Improper soldering may result in fire or explosion. It is recommended to entrust this work to certified specialists.