Failure compressor is one of the most serious and expensive breakdowns that the owner of household appliances may encounter. Usually it is accompanied by a complete absence of cold in the chambers, although the light inside continues to burn, and the engine either remains silent or makes strange clicks and immediately stalls. Many users immediately call a technician, believing that repairs are impossible without professional equipment and a specialized vacuum station.
However, if you have the skills to work with the tool, understand the principles of operation refrigeration circuit and, most importantly, access to refueling equipment, theoretically you can perform the replacement yourself. It is important to immediately understand that simply “unscrewing and screwing in” the part will not work here: the system is sealed and requires working with copper pipes, solder and refrigerant. This article describes in detail the technical side of the process so that you can assess your strengths and risks before starting work.
It is worth noting that modern refrigerators, especially models with the system No Frost, have a more complex design than old two-chamber units with a drip system. It is critically important to maintain cleanliness of the circuit and dosage accuracy Freon. An error at any stage can lead to the final failure of the unit or even a dangerous situation, so carefully study each step before picking up the burner.
Fault diagnosis and checking the compressor
Before buying a new part and disassembling the unit, you need to make sure that the problem lies precisely in the motor-compressor, and not in the start relay or thermostat. It often happens that the engine itself is working fine, but cannot start due to a burnt-out starting device. Primary diagnosis begins with a visual inspection and listening to the sounds made by the refrigerator when it tries to turn on.
For an accurate check, you will need a multimeter. You need to ring the motor windings through the contact group. The normal resistance of the working winding is usually 10-30 Ohms, and the starting winding is slightly less. If the device shows an open circuit (infinity) or a short circuit (close to zero), then electric motor it is faulty and requires replacement. It is also worth checking whether there is a breakdown in the housing.
- 🔍 Visual inspection: check the integrity of the wires, the absence of traces of burning or melting on the terminal box.
- 🔌 Checking the relay: temporarily replace the starting relay with a known good one of a similar type model to exclude its malfunction.
- 📏 Resistance measurement: use a multimeter to check the integrity of the windings and the absence of a short circuit to the case.
If you find that the compressor is humming, but does not start, and at the same time it is strong heats up, this may indicate a piston group wedge or an interturn short circuit. In such cases, it is almost impossible to revive the part. Sometimes the so-called “wedging” method by applying increased voltage helps, but doing this at home is extremely dangerous and is not recommended.
⚠️ Attention: If the compressor makes a loud metallic clang or impact when you try to start, immediately turn off the power. Further attempts to turn on may lead to the destruction of internal mechanical components and depressurization of the housing.
Necessary tools and preparation of the workplace
Replacing a compressor is not just mechanical work, but a full-fledged repair of refrigeration equipment. To perform the task efficiently, you will need specific tools, which are usually available from professionals, but can be purchased or rented by a private individual. Without vacuum pump a filling station with scales, work is impossible, since the system must be absolutely dry and filled with the exact amount of refrigerant.
The second critical tool is a gas burner. For soldering copper pipes, it is best to use an oxygen-propane torch, as it produces a higher flame temperature than conventional camping gas canisters. You will also need wire cutters, pliers, a pipe cutter and, of course, a new compressor, completely identical in power and type of refrigerant to your old unit.
Pay special attention to preparing the workplace. You will need a well-ventilated area, since soldering and possible release of freon residues may make the air unbreathable. In addition, an open flame combined with gas leakage (if any remains in the system) creates a fire risk.
- 🔥 Gas torch: necessary to heat copper connections to the melting point of the solder.
- 🛢️ Solder and flux: use refractory solder (containing silver) for copper and appropriate flux for high-quality soldering.
- ⚖️ Electronic scales: required for accurate dosage of refrigerant when filling the system.
Do not forget to prepare a container with water to check the tightness of the soldering and a pressure gauge manifold for pressure control. If you do not have experience working with open fire and copper pipes, it is better to practice on pipe scraps to understand the principle of forming a high-quality seam.
⚠️ Attention: Never use acid-containing fluxes for soldering refrigeration lines. They cause corrosion of copper from the inside, which in a short time will lead to the formation of microcracks and re-leakage of freon.
Dismantling the old compressor and preparing the system
The first stage of work is to completely disconnect the refrigerator from the power supply. The unit must then be moved away from the wall to provide access to the rear. Remove the protective plastic or metal panel covering the engine compartment. Before dismantling, it is necessary to bleed the remaining refrigerant from the system. This is done by carefully filing or cutting through the most protruding part of the capillary tube or filter-drier.
After the gas has escaped (the process may take several minutes), you can begin to unsolder the tubes. Heat the connections between the suction and discharge pipes with a torch. Once the solder melts, the tubes will separate easily. Be careful: copper heats up quickly and can cause burns. Also at this moment, old compressor oil may flow out of the tubes, so substitute a container.
Remove the terminal block from the compressor contacts and unscrew the mounting bolts or nuts holding the engine to the frame. In some models, the compressor is installed on spring shock absorbers, in others - on hard rubber feet. After disconnecting all communications, carefully remove the old unit.
At this stage, it is important to inspect the rest of the system. Check the condition of the condenser (grill at the back) for severe corrosion or damage. If the radiator is clogged with dust, it should be cleaned, as this affects the efficiency of heat transfer. It is also recommended to replace the filter drier, since the old one could be saturated with moisture and lose its properties.
Installation of a new unit and soldering of connections
Installation of a new compressor begins with its fastening to the frame of the refrigerator. Use the same fasteners and bushings that were on the old engine. If the rubber shock absorbers have lost their elasticity or are cracked, they must be replaced to reduce vibration and noise during operation.
The next step is preparing the tubes. A new compressor usually comes with plugs on the pipes. Remove the plugs immediately before soldering to prevent moisture and dust from getting into the tubes. Align the copper pipes of the refrigeration circuit with the compressor pipes. The gap should be minimal, but without interference, so as not to create mechanical stress.
The soldering process requires skill. Heat the joint evenly with a torch, moving the flame in a circle. When the copper reaches the desired temperature, touch the joint with a solder rod. The molten solder should flow into the gap on its own due to capillary action. Do not pour solder from above onto a cold tube - it will simply roll off into a ball and will not provide a seal.
☑️ Soldering quality control
After soldering all connections (suction, discharge tube and filter-drier), it is necessary to allow the system to cool naturally. Do not cool the seams with water or a damp cloth, this can lead to the appearance of microcracks at the soldering site due to a sharp temperature change.
Evacuating and charging with refrigerant
This is the most critical stage on which the durability of the repair depends. After assembling the circuit, air and moisture remain in the system, which are strictly unacceptable. Moisture freezes in the capillary tube, forming an ice plug, and the air increases the pressure in the system and worsens heat transfer. To remove air, a vacuum pump is used, connected through the service fitting.
Connect the pump to the service port (usually it is located on the discharge tube or is specially welded into the circuit). Turn on the pump and leave the system to pump out for at least 30-40 minutes. The pressure gauge should show a deep vacuum (about -1 bar or lower). This will allow all moisture to boil away from the oil and the inner walls of the tubes.
| Refrigerant type | Suction pressure (bar) | Discharge pressure (bar) | Features |
|---|---|---|---|
| R134a | 0.05 - 0.08 | 8.5 - 10.5 | Requires synthetic oil, sensitive to moisture |
| R600a (Isobutane) | 0.04 - 0.08 | 5.0 - 7.0 | Explosive, requires low dose, low pressure |
| R12 (Obsolete) | 0.08 - 0.12 | 9.0 - 11.0 | Used in older models, prohibited from production |
After evacuation, close the valve on the manifold and turn off the pump. If the pressure gauge needle begins to creep up, it means that there is a leak in the system, and the soldering needs to be redone. If the vacuum holds, you can start refueling. Refilling is carried out strictly according to the weight indicated on the refrigerator nameplate (usually on the inner wall of the chamber or at the back). Use electronic scales to control the amount of gas being charged.
Why can’t you fill it “by eye”?
An insufficient amount of freon will cause the compressor to work without stopping, trying to gain temperature, which will cause it to overheat. Excess freon will lead to an increase in pressure in the condenser, liquid freon can enter the compressor, causing water hammer, and the refrigerator will freeze slightly or not freeze at all.
Starting and testing a repaired refrigerator
After refueling the system, you need to start the compressor and check its operation. Plug in the refrigerator. The engine should start the first time, without buzzing or clicking. In the first minutes of operation, listen carefully to the unit: there should be no extraneous knocking.
Check the heating of the condenser grid. After 10-15 minutes of operation, the top of the grate should be warm to hot and the bottom should be at room temperature. This indicates proper refrigerant circulation. Also check the operation of the evaporator inside the chambers: it should be evenly covered with frost (in models with an open evaporator) or getting colder.
- ❄️ Temperature mode: after 2-3 hours of operation, the temperature in the main chamber should drop to +4...+5°C, and in the freezer - to -18°C.
- 🔇 Noise level: make sure that the vibration of the compressor is not transmitted to the refrigerator body and floor.
- 💧 No moisture: check the soldering points with a soap solution for bubbles indicating a leak.
If the refrigerator successfully reached the temperature and turned off according to the thermostat signal, the repair can be considered complete. Let the unit idle for several hours, monitoring the on and off cycles.
⚠️ Attention: If you are using R600a (isobutane) refrigerant, remember that it is a flammable gas. All soldering work should be carried out only after the gas has completely evaporated from the room. A spark from a relay or static electricity can lead to ignition.
Common mistakes when replacing yourself
Independent repair of complex equipment is often accompanied by errors that can negate all efforts. One of the most common is neglecting to replace the filter drier. The old filter contains an adsorbent that becomes saturated with moisture over time. If you leave it, moisture will enter the system, causing corrosion and ice blockage.
The second mistake is overheating of the compressor during soldering. If you heat the pipes of a new engine for too long, the heat will be transferred inside, and the oil in the crankcase may coke or burn, and the insulation of the windings may be damaged. Always use a damp cloth or heat sink gel to insulate the compressor housing from the heat of the burner.
The third mistake is incomplete vacuuming. Many beginners believe that 10 minutes of pump operation is enough. This is wrong. Moisture is the main enemy of the refrigerator. It reacts with oil, forming an acid that corrodes the motor windings from the inside. The minimum pumping time for household refrigerators should be 40-60 minutes.
FAQ: Frequently asked questions
Is it possible to replace the compressor with a more powerful one or from a different model?
Theoretically it is possible, but it is highly not recommended. The compressor is selected to match the volume of the evaporator and condenser. A more powerful engine will create excess pressure, which will lead to ruptured tubes or rapid wear. A less powerful one will not be able to provide the required temperature and will work constantly, burning out in a month. It is better to look for an exact analogue by marking.
How much does it cost to replace a compressor at a service center compared to self-repair?
The cost consists of the price of the part (about 60-70% of the price of the work) and the cost of the technician’s services. Self-repair saves money on work, but requires the purchase of expensive equipment (pump, station, tools) if they are not available. For a one-time repair, purchasing equipment may not be practical.
What to do if, after replacement, the refrigerator freezes but does not turn off?
Most likely, the freon dosage is incorrect (underfilling or overfilling) or the capillary tube is clogged. It is also possible that the thermostat is not sensing the correct temperature due to the sensor being misaligned. It is necessary to check the pressure in the system with a pressure gauge and adjust the amount of refrigerant.
Is it necessary to use nitrogen when purging the system?
Under ideal conditions, the system is purged with nitrogen under pressure before soldering to displace oxygen and prevent oxidation of copper from the inside. At home, without a nitrogen cylinder, this stage is often skipped, which reduces the repair life, but with high-quality soldering and vacuuming, the refrigerator can work for years.