An unexpected breakdown of the refrigerator is always stressful, because food supplies and the comfort of the whole family are at risk. Most often, owners of household appliances are faced with a situation where the motor-compressor stops starting, hums, but does not pump freon, or works without stopping. In such cases, the first thing you want to do is call a technician, but self-diagnosis and even repairs can save a significant amount of money and time.
Before taking active steps, you need to understand that compressor is the heart of the refrigeration unit, a complex electromechanical device. Its serviceability depends on many factors: the state of the electrical network, the integrity of the windings, the operation of the start relay and thermostat. Many problems that seem fatal, in fact, turn out to be solvable by replacing inexpensive parts.
In this article we will analyze in detail the algorithm of actions in case of failure of the injection unit. You will learn how to distinguish simple overheating from an interturn short circuit, what tools are needed for the work, and in which cases do-it-yourself repair is really justified. It is important to observe safety precautions, since work is carried out with high voltage and refrigerants.
Primary diagnostics and signs of malfunction
Any repair begins with a competent diagnosis. If your refrigerator has stopped cooling, do not rush to disassemble the back wall. First, analyze the external signs. Often the behavior of the unit itself and accompanying sounds indicate the nature of the breakdown. For example, if the motor hums for a few seconds, and then there is a click and silence, this is a classic symptom of a starting problem.
Pay attention to the temperature of the case. If the compressor hot or even hot to the touch, but the refrigerator does not freeze, this may indicate a thermal breakdown or jamming of the piston group. Normally, a running engine should be warm, but not scalding. It is also worth checking if there is a burning smell or melted insulation in the area of the electrical compartment.
⚠️ Attention: Before any manipulations with electrical components, be sure to unplug the refrigerator! Waiting 10-15 minutes after turning off will allow the capacitors to discharge, which will reduce the risk of electric shock.
There is a simple test that allows you to preliminary assess the condition of the system. Turn on the refrigerator and listen. If you hear a characteristic gurgling or fluid flow, but the cold does not come, the problem may not be in the motor, but in a freon leak or a clogged capillary tube. However, if there is deathly silence or only a quiet hum is heard without starting, the focus shifts to the electrical part.
A multimeter is often required to accurately determine the malfunction. With its help, you can “ring” the motor windings for breaks or short circuits. The normal resistance of the working winding is usually 10-30 Ohms, and the starting winding is 20-50 Ohms, although the exact values depend on the model of the compressor. What symptom do you observe in your refrigerator? data-i="61">Works without stopping compressor.
Necessary tools and workplace preparation
High-quality repairs are impossible without suitable tools. Even for basic diagnostics, you'll need more than just a screwdriver. Preparation of the workplace also plays a critical role: provide good lighting and easy access to the back of the refrigerator.
A basic kit for a home handyman should include:
- 🔧 Multimeter (tester) - required for measuring resistance and checking voltage.
- 🪛 Set of screwdrivers (phillips and flat) - for removing casings and terminals.
- 🔨 Hammer and pliers - may be needed to carefully remove jammed parts.
- 🧤 Dielectric gloves - to protect hands when working with electricity.
If you are planning a deeper repair involving replacing the motor itself, specialized equipment will be required. In particular, a torch for soldering copper tubes, a pipe cutter, a rolling machine and, of course, a new compressor along with a filter-drier. Without skills in working with gas and soldering, it is not recommended to undertake replacement of the unit, as this requires evacuation of the system and refilling with freon.
Organize the space so that all tools are at hand. Cover the floor with cardboard or old cloth to avoid losing small screws and damaging the flooring. If you're working in a kitchen, make sure there are no flammable items nearby, especially if you plan to use a blowtorch.
Checking the starting and thermal relay
One of the most common causes of compressor failure is a malfunction of the starting relay. This small block is responsible for providing an impulse to the starting winding of the motor, helping it overcome resting inertia. If the relay is burned out or stuck, the engine will hum, but will not start until the thermal protection is activated.
To check the relay, it must be removed. It is usually mounted on the side of the compressor and covered with a plastic casing. Carefully disconnect the wires and remove the device. A visual inspection can immediately give the answer: if carbon deposits, melted plastic are visible inside, or a burning smell is heard, the part requires replacement. Mechanical relays can be shaken near the ear - if a knock is heard, it means the core is broken.
An electrical test with a multimeter allows you to verify the integrity of the contacts. The resistance between the contacts must be normal or zero (in the closed state). A thermal relay, which is often built into the same housing, opens the circuit when it overheats. If it does not “ring,” it means that the circuit is broken and no current is supplied to the motor.
⚠️ Attention: When installing a new relay, make sure that it is oriented strictly according to the marks (usually the arrow points up or down). Incorrect installation will lead to immediate failure of the new part.
The cost of the starting relay is low, so they are often replaced preventively if motor diagnostics do not reveal problems. This is one of the simplest elements that can be replaced independently without special soldering skills.
☑️ Checking the relay
Diagnostics of the compressor windings
If the relay is working properly, the next step is to check the engine itself. Inside the sealed casing there are three terminals: two for windings (starting and working) and one common. Understanding their location and condition is critical for further conclusions.
Using a multimeter in resistance (Ohm) measurement mode, you need to ring the leads in pairs. You will receive three values:
| Contact pairs | Normal resistance | Possible malfunction |
|---|---|---|
| Working - Common | 10 - 30 Ohm | Open or short circuit |
| Starting - General | 20 - 50 Ohm | Open or short circuit |
| Working - Starting | Sum of two above | Short circuit |
If the device shows infinity (open) or zero (short circuit) where there should be resistance, most likely the engine has burned out. It is also important to check the breakdown on the housing. One multimeter probe is pressed against any terminal, and the other is pressed against a cleaned area on the metal body of the compressor. The device should show infinity. If there is any resistance, it means that the insulation is broken, and the operation of such a refrigerator is life-threatening.
In some cases, the windings may be intact, but the engine does not start due to the wedge. This is a mechanical failure in which the pistons or shaft seizes. Attempts to “wedge” the motor by applying increased voltage often give a temporary effect and can finally finish off the unit.
Wedging method (only for experienced ones!)
There is a method of applying 220V voltage directly to the working winding through a powerful capacitor. This creates a torque that can break the jammed shaft. However, the risk of winding breakdown or electric shock is extremely high.
Replacing the compressor: step-by-step instructions
If diagnostics show that the motor is faulty, the only option is to replace it. This is a complex process that requires soldering and refrigerant skills. You will need a new compressor, identical in power and type of refrigerant (R134a, R600a, etc.), as well as a filter drier.
The replacement process is as follows:
- Drain the old freon (at home this is done by carefully cutting the pipes, but it is better to do this in a ventilated room).
- Cut the copper tubes connecting the compressor to the system and solder them with a torch.
- Dismantle the old unit by unscrewing the mounting bolts and removing the rubber shock absorbers.
- Install a new compressor, secure it and solder the tubes, after inserting a new filter-drier.
- Vacuum the system with a special pump for 15-20 minutes to remove moisture and air.
- Fill the system with freon strictly according to the weight indicated on the refrigerator label.
The most difficult stage is soldering and refilling. Copper tubes are soldered with silver solder or a special flux for copper. It is important not to overheat the tubes so that burns do not form. After soldering, the system must be absolutely sealed.
The final stage is a leak test and a test run. If everything is done correctly, the refrigerator will begin to gain temperature. However, if you are not confident in your abilities, it is better to entrust the soldering and refueling stage to a professional who has a license to work with freons.
Typical mistakes in self-repair
Trying to save on repairs, beginners often make mistakes that lead to even more expensive breakdowns. One of the most common is ignoring the replacement of the filter drier. This element collects moisture and oil breakdown products. If you leave the old filter when replacing the compressor, the new moisture will quickly damage the expensive motor.
Another mistake is the use of unsuitable analogues. Compressors for refrigerators using R600a (isobutane) and R134a (freon) often have different designs of oil separators and type of oil. Installing a motor designed for one type of refrigerant in a system with another will lead to rapid wear and tear.
Also, do not neglect cleanliness when soldering. The ingress of dust or oxides into the copper tubes can cause blockage of the capillary system, which will manifest itself in the absence of cold, even with a working compressor. Always blow the pipes with nitrogen or dry air before soldering.
⚠️ Attention: Never turn on the compressor if its pipes are open! Moisture and dust from the air will instantly enter the system, which will lead to the formation of acid deposits inside and failure of the unit in a short time.
Remember that a modern refrigerator is a complex device where the electrical and mechanical parts are closely connected. Rash actions can upset the balance of the entire system. If after replacing the relay the situation has not changed, and you do not have soldering skills, it is more rational to contact a service center.
Why is the new compressor humming?
If after replacing the motor a strong hum appears, check whether the tubes are touching the refrigerator body or each other. The vibration is transmitted to the metal and amplifies the sound. Also, the reason may be improper installation of shock absorbers.
Frequently asked questions (FAQ)
Is it possible to repair a burnt-out compressor by rewinding the windings?
Theoretically, this is possible, but in practice it is almost impossible to implement in domestic conditions. The compressor is hermetically sealed, and to access the windings you need to carefully open the case, rewind the coils, put everything back together and ensure perfect tightness. The cost of such work and the risks exceed the price of a new unit.
Why does the compressor not turn off?
Continuous operation of the motor may indicate a freon leak, wear on the door seal, a malfunction of the thermostat, or too low a room temperature. This may also be a sign that the compressor has lost power and cannot gain the required pressure.
What is the service life of a refrigerator compressor?
The average service life of modern compressors is 10-15 years. However, with intensive use, frequent power surges or poor ventilation of the rear wall of the refrigerator, this period can be reduced to 5-7 years.
Is it dangerous to change the compressor yourself?
Yes, it is dangerous. Risks include electric shock, blowtorch burns, and fire hazards if flammable refrigerant (isobutane) is used. In addition, incorrect refilling with freon can lead to a compressor explosion.