Independent replacement or installation of a compressor in a household refrigerator is a complex technical process that requires not only plumbing skills, but also specialized equipment. Motor-compressor is the heart of the refrigeration unit, creating the necessary pressure for refrigerant circulation. If you decide to make the repair yourself, it is important to realize that simply “twisting” the wires will not help here: the system is sealed and under pressure.
Before you begin dismantling the old unit, you must carefully prepare the workplace and tools. Mistakes during the preparation phase can lead to new equipment failure or, worse, injury. In this article we will analyze in detail the connection stages, features of working with refrigerants and the nuances of the electrical circuit.
It should be noted right away that without a vacuum pump and a pressure gauge station it is almost impossible to perform high-quality work. filling with freon . Although theoretically it is possible to connect the electrics without them, a full start of the cooling system without removing air and moisture from the circuit is doomed to failure. An attempt to start a compressor in a non-vacuumed system is guaranteed to lead to failure of the motor within a few weeks.
Diagnostics and selection of a new one compressor
The first step is always to accurately identify the fault. A humming sound or lack of cold does not always mean the death of the motor; Sometimes the problem lies in the start relay or thermostat. However, if a mechanical failure or broken windings is diagnosed, replacement will be required. When choosing a new part, pay attention to the power, type of refrigerant and overall dimensions.
Modern refrigerators can be equipped with both conventional piston units and quieter ones inverter models. The latter require a special approach to connection, since they are controlled by an electronic unit and not a simple relay. Replacing an inverter often requires resoldering the control board or using a universal starting pair, which complicates the task.
- 🔍 Check the markings on the nameplate of the old motor: it should match the new one in terms of refrigerant type (R134a, R600a) and performance.
- ⚡ Make sure that the supply voltage (220V or 115V) matches your electrical network.
- 📏 Measure the distance between the mounting legs so that the new unit fits into the standard places without altering the frame.
It is important to consider that compressors from different manufacturers may have different arrangements of tubes and electrical contacts. This may require extending the copper lines or using adapters. Sealed unit must be installed strictly vertically, as required by the factory instructions, otherwise the oil will not return to the crankcase, which will quickly kill the mechanism.
⚠️ Attention: Never turn on a new compressor if it The fittings release air under pressure or, conversely, air is sucked in. There should be a factory plug inside that creates excess nitrogen pressure. If there is no plug, the unit is defective.
Necessary tools and system preparation
For high-quality work, screwdrivers and pliers alone will not be enough. You will need specialized equipment to work with refrigeration circuits. Without it, it is impossible to create a vacuum and control the pressure in the system. Gauge station This is the master’s main device, which allows you to see what is happening inside the tubes.
Also a torch for soldering copper pipes. The use of tin or soft solders in this case is unacceptable, since they will not withstand pressure and vibration. Copper is soldered with hard solder with a melting point above 600 degrees Celsius. When working with an open flame, be extremely careful not to melt the plastic elements of the housing or wiring.
☑️ Tools for replacing the compressor
In addition to the equipment, prepare consumables. You will need a new filter drier, since the old one, when the circuit is opened, instantly becomes saturated with moisture and stops working. You also need an appropriate type of freon in a cylinder with the ability to refill by weight or pressure. Don't forget about rags and eye protection.
| Tool | Purpose | Criticality |
|---|---|---|
| Pipe cutter | Smooth cut of copper pipe without chips | High |
| Vacuumator | Removing air and moisture from the circuit | Critical |
| Gas burner | Brass soldering | High |
| Electronic scales | Accurate refrigerant dosage | Medium |
Removing the old unit
The process of removing the old compressor begins with a complete disconnecting the refrigerator from the power supply. This is a basic safety rule that cannot be ignored. After this, you need to gain access to the engine compartment, usually located in the lower rear part of the body. Remove the protective cover and visually assess the condition of the wiring and pipes.
The next step is to release the residual refrigerant pressure. Even if the refrigerator is not running, gas may remain in the system. Pierce the process tube or carefully unsolder one of the fittings. This should be done in a well-ventilated area, since some types of freons in high concentrations can be harmful, and upon contact with fire, they release toxins.
Then you need to disconnect the electrical wires. Before doing this, take a photo of the connection diagram or sketch it so that when installing new equipment you do not get confused about the colors. Typically, three wires are suitable for the compressor: phase, neutral and ground, as well as wires from the start relay. Start relay and thermal protector are removed from the old motor if they are not integrated into the body of the new one.
⚠️ Attention: When When sawing or biting off copper tubing, be careful not to allow metal shavings to get into the system. Even the smallest particle of copper can clog the capillary tube, and the refrigerator will stop cooling.
After turning off all communications, unscrew the mounting bolts or nuts holding the compressor to the frame. Sometimes they can be sticky, so use a penetrating lubricant. Carefully remove the unit, trying not to damage the condenser (black coil at the back), which is often located in close proximity.
What to do with the condenser?
If the condenser (radiator) is damaged or has severe creases, it also needs to be replaced or re-rolled. The operation of a refrigerator with a damaged heat exchanger will be ineffective, and the compressor will quickly overheat due to high discharge pressure.
Installing and soldering a new compressor
Installing a new motor is done in the reverse order of dismantling. Secure the unit on rubber shock absorbers or metal feet. It is important that the compressor does not touch the metal parts of the refrigerator body so as not to transmit vibration. Now is the time to replace the filter drier, which is installed at the outlet of the condenser in front of the capillary tube.
Soldering copper connections requires skill. Pipes must be clean and free of grease. Use flux to solder copper, but apply only a minimal amount to avoid residue getting into the system. Heat the joint evenly by introducing solder into the gap between the pipe and the compressor fitting. The solder should flow inside due to the capillary effect, and not just spread on top.
Pay special attention to the process tube, through which vacuuming and filling will subsequently be carried out. Install a Schrader valve at its end in advance or prepare a place for connecting a pressure gauge hose. After cooling, all soldered joints must be checked for leaks by applying a test pressure of nitrogen (about 10-15 atmospheres) to the system.
- 🔥 Heat the tube evenly in a circle, avoiding local overheating at one point.
- 💧 Make sure that oxides do not form inside the pipe; If necessary, purge with nitrogen during soldering.
- 🛡️ Use a damp rag to protect the plastic parts of the refrigerator from the heat of the burner.
After soldering and pressure testing, if there are no leaks, you can proceed to the most important stage - vacuuming. Connect the vacuum pump to the service port and turn it on. The process of removing air and water vapor should last at least 30 minutes, and for systems with isobutane (R600a) - even longer, since this gas is fire hazardous and requires ideal cleanliness of the circuit.
Electrical connection and diagram
The electrical part of the connection often raises the most questions for novice craftsmen. A standard asynchronous refrigeration compressor motor has three terminals: Common, Start, and Run. A starting relay is connected to them, which briefly supplies voltage to the starting winding to accelerate the rotor.
The connection diagram is usually shown on a sticker next to the terminal box or on the relay itself. If the markings are erased, you can determine the contacts using a multimeter. The resistance between the working and common contacts is always less than between the starting and common contacts. Between the starting and working resistance will be the sum of the two previous ones.
Typical winding resistance circuit:R (Working) - C (Common): 15-25 Ohm
S (Starting) - C (Common): 30-50 Ohm
R(Run) - S(Start): Sum of values
It is important to correctly orient the start relay. It usually has an arrow indicating the direction "UP" or "TOP". If you install the relay upside down, the contacts will not close at the right time, and the compressor will hum, but will not start, which will lead to burnout of the windings. Also check the condition of the thermal protection relay: it must fit tightly on the compressor housing to correctly read the temperature.
For inverter compressors, the circuit is more complicated: there is no classic starting relay, and the rotation speed is controlled by an electronics unit. When replacing such a motor with a regular one (if the design allows) or when repairing the wiring, it is necessary to strictly follow the color marking of the wires, since mixing up the signal lines can burn the control board.
Refrigerant charging and testing
After evacuation, close the valve on the pump so that air does not go back into the system, and only then turn off the pump. Now you can start refueling. The amount of refrigerant is indicated on the refrigerator nameplate in grams. For accuracy, it is better to use electronic scales, placing the cylinder on them, and control the weight of the gas lost.
If there are no scales, you can use pressure as a guide, but this is a less accurate method, depending on the ambient temperature. For R134a freon, the working suction pressure is usually 0.05-0.08 MPa, for R600a it is lower, about 0.03-0.05 MPa. Refill with the compressor running, supplying gas in small portions through the service port.
Control the temperature of the evaporator (inside the freezer) and condenser (at the back). The evaporator should be evenly covered with frost, and the condenser should be heated along its entire length. If only the upper part of the radiator heats up, there may be an air lock in the system or low freon. If the entire radiator is cold, there is too much freon or the capillary is clogged.
⚠️ Attention: An excess amount of freon is just as dangerous as its deficiency. Overloading the system with liquid refrigerant can lead to water hammer and destruction of the compressor valves. Refill strictly according to the norm.
After refueling and checking operation for 15-20 minutes, the service tube is clamped with a special clamp and sealed. This is the final stage of creating a sealed circuit. Be sure to check the soldering area with a soap solution for bubbles.
Is it possible to replace an R134a compressor with an R600a?
Theoretically it is possible, but this requires a complete flushing of the system, an oil change (R600a uses synthetic POE, R134a often uses mineral or alkylbenzene) and recalculation of the length of the capillary tube. Without in-depth knowledge of refrigeration technology, such a replacement is not recommended due to the fire hazard of isobutane.
Why is the compressor hot to the touch?
The normal operating temperature of the compressor housing can reach 70-90 degrees Celsius. However, if it is too hot to touch, this may indicate a malfunction of the blower fan (if any), contamination of the condenser, excess freon, or an interturn short circuit in the windings.
Is it necessary to change the oil in a new compressor?
No, new compressors are supplied already filled with the required amount of oil. It is strictly forbidden to drain it or add it “by eye”. Violation of the oil level will lead either to scuffing of the piston group or to water hammer.
How long should the refrigerator operate after replacement?
The first start should last at least 2-3 hours without loading food. During this time, the system will return to operating mode, and you will be able to evaluate the quality of cooling and the absence of leaks. It is recommended to fully load food only after reaching a stable temperature in the chambers.