Replacement compressor is one of the most difficult and important operations when repairing household appliances. If your refrigerator has stopped freezing, and diagnostics show a motor malfunction, you will be faced with the task of dismantling it and installing a new unit. This process requires not only the availability of specialized tools, but also a deep understanding of the operating principles of the refrigeration circuit.
Errors at the connection stage can lead to repeated equipment failure, refrigerant leakage, or even fire. That is why it is important to strictly follow the technological sequence of actions and not neglect safety precautions. In this article, we will look at all the nuances of how to properly connect a compressor so that the equipment will serve for many years.
It is worth noting right away that this procedure is not a simple replacement of a part like a light bulb or thermostat. This requires system sealing, evacuation and precise refueling freon. Without the appropriate skills and equipment, you should not take on the job, since the risk of making a critical mistake is extremely high.
Preparation of the workplace and the necessary tools
Before you start disassembling the refrigerator, you need to prepare all the tools and consumables. You will need not only a standard set of screwdrivers and pliers, but also specific equipment for working with copper pipes. The main tool will be torch with solder, allowing you to create reliable solder connections.
It is also critically important to have on hand vacuum pump and a pressure gauge station. These devices are necessary to remove air and moisture from the system before charging with refrigerant. An attempt to start the compressor without evacuation will lead to the formation of ice plugs in the capillary tube and rapid failure of the new part.
Be sure to make sure that you have access to fresh air or good ventilation. Working with open flames and possible gas leaks requires caution. Do not forget that some types of freon, when in contact with a flame, can form toxic compounds.
- 🔧 A set of pipe cutters and rolling tools for preparing copper pipes.
- 🔥 Gas burner with a cylinder and refractory solder (silver or copper-phosphorus).
- 📉 Vacuum pump and charging station with scales for precise dosage of refrigerant.
- 🧤 Protective gloves and glasses to protect against solder and oil splashes.
⚠️ Attention: Using aluminum solder instead of copper-phosphorus or silver when Working with copper compressor tubes is unacceptable. Such connections cannot withstand vibration and high pressure, which is guaranteed to lead to depressurization of the circuit in the near future.
Dismantling the old compressor and preparing for installation
The process begins with completely disconnecting the refrigerator from the power supply. Only then can you remove the rear access panel to the motor. The first step is to carefully cut or saw through the copper tubes connecting the compressor to the condenser and evaporator. This should be done at a distance of 10-15 cm from the motor body in order to leave a margin for rolling.
After freeing the unit from the tubes, disconnect the electrical contacts. They are usually secured with terminals that are easily removable, but can be oxidized. Before installing a new one motor-compressor carefully inspect it for transport plugs. Plastic or rubber plugs should always be installed on the fittings of a new part to prevent moisture and dust from getting inside.
These plugs should be removed immediately before soldering. If the new compressor has been lying without plugs even for several hours in conditions of high humidity, it is recommended to dry it in a drying cabinet or warm it with a hairdryer to remove condensation from the windings and the internal cavity.
It is also important to drain the old compressor oil from the dismantled unit and assess its condition. The color and smell of the oil can indicate the cause of the breakdown. If the oil is black and has a burning smell, it means that there was a winding breakdown in the system, and the circuit requires thorough purging with nitrogen.
Technology for soldering copper tubes
The most critical step is connecting the copper tubes to the compressor pipes. First you need to clean the ends of the tubes from oxides and old insulation. An even cut is made with a pipe cutter, after which the edges are processed with a rimmer or a needle file to remove burrs. This will ensure a tight fit of the parts during soldering.
The soldering process requires uniform heating of the joint. The torch flame is directed at the junction of the tube and the nozzle, and not at the solder itself. When the metal heats up to the desired temperature, the solder will begin to melt and flow into the gap under the influence of capillary effect. It is important not to overheat copper tubes, as this can lead to burning or changing the structure of the metal.
When soldering the suction and discharge lines, make sure that the flame does not reach the electrical unit of the compressor. For protection, you can use a wet cloth or a special heat-dissipating screen. All connections must be sealed and visually homogeneous, without cracks or sagging.
☑️ Checklist for proper soldering
⚠️ Attention: Never try to speed up the cooling of a soldered joint with water or a damp rag. A sharp temperature change creates thermal stress, which can cause microcracks in the seam, invisible to the eye, but leading to leakage of freon under pressure.
Electrical connection diagram
The electrical connection diagram of the compressor may vary depending on the type of starting device. In modern refrigerators, most often there are circuits with a start-up protection relay (PPR) or with an electronic control module. Incorrect connection of the wires can lead to instantaneous burnout of the windings or starting capacitor.
Usually, a contact wiring diagram is printed on the relay body or in the technical documentation of the refrigerator. The main terminals are designated as C (common), R (working winding) and S (starting winding). It is important to follow the color coding of the wires, but always double-check them with a multimeter, as manufacturers may change standards.
If your refrigerator has an old-style starting relay, make sure it matches the power of the new motor. A mismatch in the relay characteristics can result in the compressor humming but not starting, or starting with strong vibration and overheating.
| Winding type | Designation on the diagram | Wire color (standard) | Resistance (Ohm) |
|---|---|---|---|
| General | C (Common) |
Green / White | Low (sum of R and S) |
| Working | R (Run) |
Brown / Black | Medium |
| Trigger | S (Start) |
Blue / Red | High |
| Ground | PE |
Yellow-green | 0 (continuity to the body) |
After connecting all contacts, securely fasten the relay block to the compressor terminals. It should fit tightly, without play. Check the integrity of the insulation of the wires going to the thermostat and control module. Any damage to the insulation should be repaired using heat shrink.
What to do if the compressor hums, but does not start?
If after connecting you hear a hum, but the engine does not start, immediately turn off the power. This could mean a jammed mechanism, a faulty start relay, or low mains voltage. Also, the cause may be incorrect phasing of the windings or lack of starting torque due to a faulty capacitor.
Evacuation and refrigerant charging
After all mechanical and electrical connections have been made, the stage of preparing the system for operation begins. There should be no air or moisture left in the circuit. To do this, a vacuum pump is connected to the process pipe (usually the filling pipe on the compressor). The process of pumping out air takes from 20 to 40 minutes, depending on the volume of the system and the power of the pump. The residual pressure should be no more than 50-100 microns. If the pressure stops falling or begins to rise after stopping the pump, then there is a leak in the system that needs to be found and eliminated. vacuum pump.
The process of pumping out air takes from 20 to 40 minutes, depending on the volume of the system and the power of the pump. The residual pressure should be no more than 50-100 microns. If the pressure stops falling or begins to rise after the pump is stopped, then there is a leak in the system that needs to be found and repaired.
Critical important: Filling the refrigerator must be done strictly according to the weight indicated on the nameplate (nameplate), accurate to the nearest gram. Using the eye method or pressure on a pressure gauge without weighing is unacceptable, since the amount of refrigerant depends on the brand of freon and the volume of the chamber.A pressure gauge station is used for refueling. The freon bottle connects to the blue hose, the yellow hose goes to the vacuum pump, and the red hose goes to the vacuum valve (or a two-way valve is used). After evacuation, the valve is closed, the pump is turned off, and the valve on the cylinder opens to fill the system.
- 🧊 R134a is a modern environmentally friendly freon that requires the use of synthetic POE oil.
- ❄️ R600a (isobutane) is an explosive gas, requires special care and the absence of sparks when work.
- 🌪️ R12 is an obsolete freon, prohibited for production, but found in old equipment.
After refueling, it is necessary to solder the filling tube. This is done by clamping the tube with clamping pliers, followed by soldering the tip. This guarantees complete tightness of the system. Then the compressor is turned on to check the operation and distribution of the refrigerant throughout the circuit.
Operation check and diagnostics
Starting the compressor after installation is the moment of truth. During the first minutes of operation, listen carefully to the sounds emanating from the unit. A smooth hum without knocking, clanging or vibration indicates correct installation. You should also monitor the temperature of various parts of the circuit.
After 15-20 minutes of operation, the condenser (grid at the back of the refrigerator) should begin to heat up evenly. The suction tube leading to the compressor should be slightly cooled and covered with dew, but not frost. If the tube becomes covered with a “fur coat,” this is a sign of excess freon or a malfunction of the thermostat.
Be sure to check the compressor current consumption using a current clamp. The value should not exceed the nominal values specified in the device passport. Excess current indicates an overload, a malfunction in the electrical part or problems with the mechanics of the compressor.
⚠️ Attention: If you are working with R600a freon, remember that this is a flammable gas. All soldering work should be carried out only after thoroughly ventilating the room. Sparking relay contacts in the presence of an R600a leak can lead to a volumetric explosion.
Frequent errors and troubleshooting
Even experienced craftsmen sometimes make mistakes that negate all the work. One of the most common problems is moisture getting into the system. This happens if the vacuum was not carried out for long enough or a low-quality pump was used. Moisture freezes in the capillary tube, blocking the circulation of freon.
Another common mistake is overheating of the compressor during soldering. If you heat the pipes for too long, the oil inside may become coked and the winding insulation may be damaged. It is also dangerous if solder gets inside the tube, which creates an obstacle to the flow of refrigerant and increases the discharge pressure.
You should not ignore the condition of the filter drier. Every time the system depressurizes (and replacing a compressor means a complete depressurization), the filter necessarily must be replaced with a new one. The old filter is already saturated with moisture and will not be able to effectively clean the refrigerant, which will lead to corrosion of parts from the inside. needs to be replaced with a new one. The old filter is already saturated with moisture and will not be able to effectively clean the refrigerant, which will lead to corrosion of the parts from the inside.
If after all the procedures the refrigerator does not freeze, check the operation of the thermostat and the air damper (if there is one). Sometimes the problem lies not in the new compressor, but in adjacent systems that could also have suffered during previous operation or were damaged during installation.
Is it possible to replace a compressor without soldering the tubes?
Theoretically, there are couplings for connecting tubes, but their use in domestic refrigerators is highly not recommended. Vibration and temperature changes will quickly destroy the mechanical connection, and freon will come out. Soldering is the only reliable way to ensure tightness for years.
How long should a new compressor run before the first shutdown?
The operating time depends on the food load, room temperature and thermostat settings. The first cycle can last from 40 minutes to 2 hours. If the compressor operates continuously for more than 3-4 hours and does not gain temperature, it means there is a freon leak or the thermostat is faulty.
Does the system need to be flushed with nitrogen when replacing the compressor?
Yes, if the old compressor burns out, combustion products and acidic compounds remain in the system. Purging with nitrogen under pressure is mandatory to clean the circuit. If the compressor simply stops pumping without shorting, careful evacuation may be sufficient, but purging will not hurt.
Why does the new compressor get hotter than the old one?
Modern compressors often have a higher energy efficiency class and operate at higher housing temperatures. If the temperature does not exceed 80-90 degrees and there is an outflow of heat (a fan or natural convection is running), this may be normal. However, check the current consumption.