Sudden stop refrigeration unit is always a stress that jeopardizes the safety of food and requires an immediate solution. Often the cause of the breakdown is compressor, which stops starting, hums without effect, or is completely silent when voltage is applied. In such situations, many equipment owners think about calling a technician, but the cost of work, including travel and spare parts, can be a significant part of the price of a new device.
Independent replacement of the motor is possible, but requires not only technical skill, but also special equipment for working with refrigerant. Refrigerator is a sealed system under pressure and violation of repair technology will lead to rapid failure of a new expensive part. Before you begin dismantling, you need to soberly assess your strength, the availability of tools and understanding of the physical processes occurring inside the circuit.
In this article we will analyze in detail the entire process, from diagnostics to the final launch of the system, paying special attention to safety precautions. You will learn what nuances are hidden by soldering copper tubes and why evacuation of the circuit is a mandatory step, and not just a recommendation. Remember that the quality of your work directly affects the service life of the equipment after repair.
⚠️ Attention: All work on replacing the compressor should be carried out only with the refrigerator completely disconnected from the power supply. Residual voltage in the starting relays or capacitors can lead to electric shock.
Fault diagnosis and selection of a new compressor
Before disassembling the unit, you need to make sure that the problem lies in the motor, and not in the starting relay, thermostat or wiring. If compressor it hums, but does not start, or it instantly heats up and turns off, these are sure signs of its malfunction. However, sometimes the culprit is the start-up protection relay, which costs much less and is much easier to change.
For accurate diagnosis, you should ring the motor windings with a multimeter. Normal resistance between the contacts indicates the integrity of the windings, while an open or short circuit indicates the need for replacement. It is also important to check whether the housing is shorted to the windings, which is a critical defect.
When choosing a new spare part, be guided by the markings of the old device. Power, type of refrigerant (for example, R134a or R600a) and type of oil must strictly correspond to the original or its proven analogues. Installing a motor that is not suitable for power will lead to ineffective operation of the system or repeated breakdown.
- 🔍 Check the integrity of the windings with a multimeter: the resistance should be within normal limits.
- ⚡ Make sure there is no breakdown to the housing by measuring the resistance between the contacts and the copper tube.
- 🏷️ Check the markings of the old and new compressor: the type of refrigerant and power must match.
- 🔊 Assess the condition of the starting relay: sometimes replacing it solves the problem without buying a new motor.
Necessary tools and worker training places
High-quality repairs are impossible without the appropriate equipment. To replace compressor you will need not only a standard set of plumbing tools, but also specific equipment for working with refrigeration circuits. The main tool will be a gas torch with solder or a special soldering iron for copper pipes, since the connection must be absolutely tight.
The second critical element is a vacuum pump and a pressure gauge station (manifold). Without them, it is impossible to create a vacuum in the system and fill freon under the correct pressure. The use of cans for refilling car air conditioners in domestic refrigerators is unacceptable, since they do not allow you to control the exact amount of refrigerant and the presence of air in the system.
Prepare the workplace: it should be well lit and ventilated. You'll need a stable table to tilt the refrigerator on, and access to power for your soldering equipment. Also stock up on rags for wiping oil and alcohol for degreasing soldering areas.
☑️ List of tools
Dismantling the old compressor and preparing the system
The process begins with access to to the motor. In most models refrigerator the compressor is located in the lower rear part and is covered with a metal or plastic casing. Remove the casing, disconnect the start relay and the safety thermostat. Be careful, as plastic elements become brittle over time.
The next step is removing the old refrigerant. If there is gas left in the system, it must be vented in a well-ventilated area or outdoors, as it can be flammable (in the case of isobutane) or harmful to breathe. After bleeding the gas, you need to use wire cutters or file the suction and discharge tubes of the compressor.
Now you can start unsoldering. Heat the joints of the tubes with the compressor with a torch to the melting temperature of the solder. Once the solder has melted, carefully remove the tubes. It is important not to overheat the adjacent elements and the compressor itself, so as not to damage the varnish coating of the windings inside if you plan to revive it, although with a complete replacement this is no longer relevant.
⚠️ Attention: When desoldering, use a damp rag or heat-removing gel so that the flame does not damage the varnish coating of the windings or plastic elements near the place soldering.
After dismantling the old motor, it is necessary to purge the system with nitrogen. This will remove flux combustion products, oxides and possible moisture that could get inside when opening the circuit. If you skip this step, capillary tube it may clog and the refrigerator will stop freezing again after a short time.
Why is nitrogen needed?
Blowing with nitrogen under pressure allows you to displace residual moisture and flux combustion products from the system. If moisture is left inside, it will freeze in the capillary tube, creating an ice plug, or react with the oil, forming acid, which will destroy the compressor from the inside.
Installing a new motor and soldering connections
Install the new one compressor into the original location using the standard mounting bolts and shock absorbing bushings. Vibration during motor operation is high, and reliable fixation is necessary to prevent noise and destruction of the tubes. Connect the electrical part: starting relay and thermal protection, making sure that the contacts are connected correctly according to the diagram on the relay body.
Now we move on to soldering. Clean the ends of the copper condenser and evaporator tubes, as well as the fittings of the new compressor. Insert the tubes into the fittings with a small gap (about 1-2 mm until it stops). Heat the joint with a torch evenly in a circle, then insert the solder rod. The solder should flow into the gap itself under the action of capillary effect.
It is critically important not to overheat the soldering area: the copper should not melt, only the solder melts. Excess solder can get inside the tube and clog capillarywhich will be fatal to the system. After soldering, allow the connections to cool naturally without blowing on them or cooling them with water.
| System element | Connection type | Soldering temperature | Important nuance |
|---|---|---|---|
| Compressor (fittings) | Copper-Steel/Copper | ~700-800°C | Do not heat for a long time, so as not to burn the rubber bands inside |
| Condenser | Copper-Copper/Steel | ~700°C | Monitor the flow of solder so as not to clog the tube |
| Filter drier | Copper-Copper | ~700°C | Soldering quickly, the filter should not overheat |
| Capillary tube | Copper-Copper | ~650°C | The thinnest element, requires caution |
Vacuum and refrigerant charging
After installing all the elements and replacing the filter-drier (this is mandatory for any opening of the circuit!) it is necessary to remove air and moisture from the system. To do this, a pressure gauge station and a vacuum pump are connected to the service fitting (which you should have installed on the process tube of the compressor or use a standard one).
Turn on the pump and watch the vacuum gauge arrow. The system must be evacuated to a high vacuum (usually around -1 bar or 29-30 inHg). The operating time of the pump depends on the volume of the system, but is usually at least 15-20 minutes. This is necessary to evaporate moisture, which at atmospheric pressure does not boil at room temperature.
After evacuation, close the valve on the manifold and turn off the pump. Leave the system under vacuum for 10-15 minutes. If the pressure gauge needle remains in place, then the system is sealed. If the pressure increases, there is a microcrack or poor-quality soldering somewhere, and the process must be repeated.
Refilling freon is carried out with the compressor running. Open the valve on the refrigerant cylinder and introduce gas into the system. The suction pressure must be appropriate for the type of refrigerant and the ambient temperature. For R134a this is usually about 0.6-0.8 bar, for R600a - about 0.4-0.5 bar (at rest and in operation the values are different).
⚠️ Attention: The exact amount of refrigerant is determined according to the refrigerator passport (in grams) or according to the current consumption of the compressor. A lack of freon will lead to poor cooling, and an excess will lead to increased energy consumption and load on the motor.
Checking the tightness and the first start
After refueling and disconnecting the filling station (the tube is sealed), it is necessary to check the system for leaks. The easiest way is to use a soap solution. Apply it to all solder joints and watch for bubbles to appear. Even a microscopic bubble indicates a leak that needs to be fixed.
Plug in the refrigerator. In the first minutes of operation compressor it may work louder than usual until the pressure in the system stabilizes. Check the current consumption with an ammeter: it should correspond to the rating indicated on the motor tag. Excess current indicates problems in the system or the motor itself.
Evaluate the operation of the refrigeration chamber. After 30-40 minutes of operation, the evaporator in the freezer should be evenly covered with frost (“crying” or getting cold, depending on the NoFrost system). The condenser (grid at the back) should heat evenly from top to bottom.
- 🧼 Generously lubricate all seams with soapy water to look for gas leaks.
- 🌡️ Control the temperature: the freezer should freeze the water in 1-2 hours.
- 🔊 Listen to the sounds: extraneous clanging or humming indicates vibration of the tubes.
- 📉 Follow the cycle: the refrigerator should turn off when the set temperature is reached.
What to do if the refrigerator does not freeze after replacement?
If after replacing the compressor and refilling with freon, the cold does not appear, there may be several reasons: blockage of the capillary tube (often due to moisture or dirt), leakage of freon through a poor-quality seam, or a malfunction of the new compressor itself (rarely, but defects do occur). Also check the operation of the thermostat and the start relay.
Is it possible to use a compressor from another refrigerator?
Yes, you can if the main parameters match: power, type of refrigerant, type of oil and overall dimensions for installation. However, it is better to look for a complete analogue by marking, since different models may have different performance, which will upset the balance of the system.
How much does it cost to replace a compressor with your own hands?
The cost consists of the price of the compressor itself (from 3,000 to 8,000 rubles depending on the model), the cost of a filter drier, solder, freon and rental equipment (if you don’t have your own). As a result, the savings compared to the service can be 50-60%, but the risks are taken by the self-taught master.
Is it necessary to change the oil in a new compressor?
No, new compressors are supplied already filled with the required amount of oil. There is no need to add or change the oil in them, unless you are engaged in a specific overhaul of old engines, which is impractical to do at home.