Sooner or later, every owner of household appliances is faced with a situation when the refrigerator stops cooling, and the temperature inside rises. Often the cause of a breakdown is a failure motor-compressor, which is the heart of the entire cooling system. Many amateur craftsmen, trying to save on the services of a service center, wonder about replacing this unit on their own, searching the Internet for videos with a step-by-step process.
However, it is worth understanding that replacing a compressor is not just a mechanical replacement of a part, as is the case with a door handle or shelf. This is a complex technical process that requires special knowledge, tools and safety precautions. In this article, we will analyze in detail how to properly connect the compressor to the refrigerator, what to pay attention to when watching video instructions, and what nuances need to be taken into account to successfully complete the repair.
Before taking active steps, it is necessary to conduct a thorough diagnosis. The absence of cold does not always mean the death of the engine; sometimes the problem lies in start relay or a freon leak. If you are convinced that the compressor is humming but does not start, or is completely silent even though the electronics are working, then replacement is inevitable. It is also important to remember that to seal the system, you will need special equipment, which not every home craftsman has.
Fault diagnosis and tool preparation
The first stage of any repair is to accurately determine the cause of the breakdown. If you plan to replace the compressor, make sure that this is the problem. Users often confuse a motor breakdown with a malfunction thermostat or the starting device. Check if voltage is supplied to the motor windings. If the current flows, but the shaft stands still, and the unit itself gets very hot, most likely, an interturn short circuit or jamming of the piston group has occurred.
To carry out the work, you will need a specific set of tools, without which connecting a new unit is impossible. A regular set of screwdrivers and pliers will not be enough here. You will need a pipe rollingkit to create airtight connections for copper lines. A gas cutter or special scissors for cutting copper tubes is also required, since cutting them with a regular hacksaw is impossible due to chips getting inside the system.
A critical element is the presence of a vacuum pump and a pressure gauge station. Without pumping out air and moisture from the system, charging with refrigerant is impossible, and the remaining air inside will lead to rapid failure of the new compressor. In addition, you will need a torch for brazing, since soft tin solder will not withstand the pressure and vibrations in the cooling system.
⚠️ Attention: Before starting any work on disassembling the refrigerator, be sure to disconnect the device from the electrical network. Working with high voltage and flammable gases requires maximum caution and compliance with fire safety rules.
Prepare the workplace: it should be well ventilated, since during soldering and the possible release of residual freon, the air in the room can become dangerous to breathe. Make sure you have a fire extinguisher and personal protective equipment such as gloves and goggles in advance. Do not forget that refrigerant in certain concentrations can be harmful to health.
Removing the old compressor and preparing the system
The dismantling process begins with removing the protective casing located in the lower rear part of the refrigerator. Under it you will see the compressor itself, the capacitor and the start relay. The first step is to photograph the wiring diagram so that when installing a new unit you do not mix up the contacts. This is especially important for models with electronic control, where an incorrect connection can burn the control module.
The next step is to release the residual refrigerant pressure. Do not bite off the tubes immediately if there is pressure in the system - this may lead to oil splashing. Carefully file the filling tube (fitting) and let the gas escape. After this, you can cut through the suction and discharge tubes, moving a few centimeters away from the compressor housing to leave room for subsequent rolling.
When dismantling the old unit, pay attention to the condition of the oil that has leaked from the system. If it is dark, has a burning smell, or contains metal shavings, this indicates serious damage. In this case, simply replacing the compressor may not help, since combustion products and contamination could spread throughout the entire circuit. It will be necessary flushing the system nitrogen and replacing the filter-drier, otherwise the new motor will not last long.
- 🔧 Disconnect the wires from the compressor terminals, having previously noted their location.
- 🔧 Remove starting relay and protective casing from the terminal box.
- 🔧 Cut through the copper tubes holding the compressor to the refrigerator frame.
- 🔧 Unscrew the mounting bolts or nuts that secure the motor to the chassis.
After physically removing the old compressor, it is necessary to prepare a place for installing a new one. Check the vibration isolators (rubber feet) on which the engine stands. If they are dry or cracked, they must be replaced, otherwise the new compressor will operate with strong noise and vibration. Also inspect the condenser for mechanical damage and corrosion.
Selecting and installing a new compressor
Selecting a new compressor is a crucial moment. You need to focus not only on overall dimensions, but also on technical characteristics: power, type of refrigerant (R134a, R600a, R12) and performance. Often on the body of an old motor there is a nameplate with markings that can be used to select an analogue. It is important to consider that compressors for different types of freon may have different oil designs and are not interchangeable without a deep rework of the system.
Installation of a new unit is carried out in the reverse order. Secure the motor to the frame using standard fasteners. Do not overtighten the bolts to avoid damaging the threads or housing. Before soldering the tubes, make sure that the distances to the walls of the refrigerator and other components are maintained, otherwise vibration during operation will lead to friction and eventual depressurization.
Pay special attention to installation filter drier. This element must be changed whenever the circuit is opened, as it absorbs moisture from the air. Install the filter into the gap of the capillary tube or condenser, observing the flow direction indicated by the arrow on the housing. Do not heat the filter with an open flame when soldering, use a damp cloth for cooling so as not to damage the zeolite inside.
Now you can begin connecting the copper tubes. Use the rolling method to create a secure connection. The end of the tube is flared into a cone, a nut is put on, and the connection is tightened. The quality of rolling directly affects the tightness of the system. If you use the soldering method, monitor the temperature: the copper should melt the solder, but not burn itself.
Connection diagram for the electrical part and relays
The electrical diagram for connecting the compressor is relatively simple, but requires care. The terminal block usually has three contacts: two for the starting winding and one for the working winding, as well as grounding. It is connected to the compressor start-protection relay, which supplies an impulse to the starting winding to start the engine and turns it off after gaining speed.
In modern refrigerators, posistor-type relays are often used. They have no moving parts and switch windings by changing resistance when heated. When replacing a compressor, it is strongly recommended to change the relay to a new one that matches the engine model. An old relay may have impaired characteristics, which will lead to an unstable start.
The color coding of the wires may differ from one manufacturer to another, so always check the electrical diagram posted inside the refrigerator or in the technical documentation. An incorrect connection may cause the compressor to hum but not start, or the winding will burn out.
⚠️ Attention: Make sure the ground wire is securely connected to the compressor body. This is critically important for operational safety, since breakdown of the insulation on the housing can lead to electric shock when touching the refrigerator.
To check the correct assembly, you can conduct a short test run. However, this should be done only after the system has been evacuated and checked for leaks. Plug in the refrigerator and listen to the engine start. It should work smoothly, without strong jerks or extraneous sounds. If you hear a buzzing sound, but there is no startup, immediately turn off the power and check the relay.
| Relay type | Principle of operation | Symptoms of malfunction | Replaceability |
|---|---|---|---|
| Start protection (RT) | Electromagnetic with thermal release | Clicks, no start, overheating | Requires current selection |
| Posistor (PZR) | Heating of the crystal and change in resistance | The compressor hums, but does not start | Universal analogues |
| Inverter | Frequency motor control | Electronics error, unstable operation | Only original or complete set |
Evacuation and refrigerant charging
The most difficult stage for a home master is creating a vacuum and charging the system. After soldering all connections, it is necessary to connect the pressure gauge station to the service connection. Turn on the vacuum pump and watch the pressure gauge needle. It should go negative, showing deep depression. This process removes air from the system and, more importantly, moisture, which, if frozen, can block the capillary tube.
Evacuation should last at least 15-20 minutes. After turning off the pump, close the valve and leave the system for a while, observing the arrow. If the arrow starts to creep up, it means there is a leaks somewhere (a microcrack in the solder or bad rolling). In this case, you cannot refill the refrigerant; you need to look for and eliminate the leak.
Refilling is carried out strictly according to the weight indicated on the refrigerator nameplate. The use of a weighing container or graduated cylinder is mandatory. An excess of freon is just as dangerous as its deficiency: it can lead to water hammer in the compressor or ineffective operation of the system. For different types of refrigerants (R134a, R600a), different hoses and oils are used; they cannot be mixed.
☑️ Check before starting
After filling, solder the service fitting. This must be done carefully so as not to damage the tube and release gas. Cool the soldering area immediately with a damp cloth. The system is now sealed and ready for the first start. Turn on the refrigerator and let it work for several hours, monitoring the temperature in the chambers.
Typical connection errors and their consequences
One of the most common mistakes is neglecting to replace the filter-drier. Novice craftsmen often believe that if the system has not been closed for long, then the moisture will not have time to do any harm. However, even a small amount of moisture leads to the formation of an ice plug in the capillary, and the refrigerator stops freezing after a few days of operation.
Another mistake is overheating of the compressor during soldering. If you heat the tubes connecting to the motor housing for a long time, you can damage the internal insulation of the windings or melt the plastic elements of the valve group. Always use heat-dissipating clips or a damp cloth so that heat is not transferred to the unit itself unit.
Incorrect selection of the compressor for performance is also common. Installing a more powerful motor “by eye” will lead to the evaporator freezing unevenly, and the chamber will be too cold or, conversely, warm due to an imbalance in the system. The capillary tube is selected for a specific performance, and its replacement is a complex calculation process.
⚠️ Attention: When working with R600a (isobutane) refrigerant, take special care. This is flammable gas! Any spark when soldering in a confined space with a leak of this gas can lead to an explosion. Carry out work only in a ventilated area away from open fire.
Do not forget about the quality of soldering. Using too much solder may clog the tube from the inside. The solder should flow into the gap due to capillary effect, and not fill the entire volume of the pipe. Control the amount of supplied material.
What to do if after replacement the compressor hums loudly?
A loud hum can be caused by several reasons: incorrect installation (tubes touching the body or cabinet walls), a defect in the new compressor itself (defect), or lack of proper shock absorption. Check whether the tubes are vibrating against other parts. If the shock absorbers are intact and the settings are correct, you may have received a defective unit.
Tightness check and first start
Before final sealing and start-up, it is necessary to conduct a final tightness check of all connections. The easiest way is to use a soap solution. Apply it to all soldered and rolled joints. The appearance of bubbles will indicate the location of the leak. Even a microscopic leak will eventually lead to loss of freon and breakdown.
The first start-up should be supervised. Turn on the refrigerator and immediately check the current consumed by the compressor using a current clamp. It must correspond to the nominal value specified in the documentation. Exceeding the current indicates an overload, possibly due to problems with the capacitor or the motor itself.
Evaluate the operation of the system in dynamics. The condenser (grid at the back) should heat up evenly, starting from where it exits the compressor. The evaporator inside the chamber should begin to cool. If one part of the condenser is hot and the other cold, or gurgling is heard, there may be an air lock in the system or a problem with the capillary.
Let the refrigerator run idle for several hours. During this time, it should reach the set temperature and turn off (if the thermostat is not broken). If the operating cycle is normal and the temperature in the chambers is normal, the repair can be considered successful. Install the back cover and return the refrigerator to the place of use.
Is it possible to replace the compressor without soldering and a vacuum sealer?
Theoretically, there are systems with quick-release connections (Clack-Valve), but they are not standard for household refrigerators. Without evacuation, the system will inevitably remain with moisture and air, which will lead to corrosion from the inside and blockage of the capillary. Therefore, a full repair without special equipment is impossible.
Why does a new compressor get hotter than the old one?
Modern compressors often operate at higher housing temperatures to increase energy efficiency. Heating can also be caused by improper filling (excess freon) or poor ventilation in the installation niche. If the temperature does not exceed 80-90 degrees and the refrigerator freezes, this may be normal.
How long should the compressor operate after replacement?
The first cycle of operation after refueling can be long (up to 2-3 hours), since the system needs time to gain temperature and distribute the oil. If the refrigerator does not turn off for more than 5-6 hours or works without a break for days, it means that there is a problem with the thermostat, a freon leak or a seal is broken.
Is it necessary to flush the system if the old compressor has burned out?
Yes, if the winding has burned out, combustion products and acid remain in the system. Without flushing with nitrogen and special solvents, the new compressor will quickly fail. If the compressor simply stops pumping without burning, flushing may not be necessary, but replacing the filter is required.