Failure of a cooling circuit is always stressful, because we are talking about the safety of products. Often the cause of the breakdown is the motor, and replacing it requires not only technical skills, but also a precise understanding of the electrical circuit. Correct connection of the compressor is a critical step, since an error in the sequence of actions can lead to the final failure of the new part or even a wiring fire.
Before To begin dismantling old equipment, it is necessary to completely de-energize the unit. This is a basic safety rule that cannot be ignored. In this article we will look in detail at how it is done replacing the motor, what tools you will need and what to pay attention to when working with electrical contacts.
It is important to understand that modern refrigerators may have different designs of starting devices. Somewhere a classic combination of starting and thermal relays is used, and somewhere - a single inverter unit. Despite the differences, the basic principles of switching remain similar, however, the nuances must be taken into account.
Diagnostics of the malfunction and preparation of tools
Before you start disassembling, you should make sure that the problem lies in the motor. If the unit hums, but does not generate cold, or characteristic clicks are heard followed by attenuation, there is a high probability of a malfunction of the starting mechanism or motor windings. Diagnostics of the compressor begins with a visual inspection and testing the windings with a multimeter.
To carry out work you will need a standard home craftsman's kit, supplemented with specific devices. You should not try to replace a part by eye, since modern control systems are sensitive to the quality of connections. You will need:
- 🔧 A set of screwdrivers (Phillips and flat) for removing the casings.
- 🔌 Multimeter for checking the winding resistance.
- ✂️ Side cutters or wire cutters for cutting wires.
- 🔥 Soldering iron and solder for reliable connection of contacts.
Pay special attention to the condition of the wiring. If the insulation of the wires going to the compressor is melted or cracked, they must be replaced. Old wiring can cause a short circuit immediately after starting a new engine.
How to check the windings with a multimeter?
Switch the device switches to resistance measurement mode (Ohm). Locate the three contacts on the compressor. Measure the resistance between them. Between the starting and operating windings, the sum should give resistance between the common contact and the third terminal. If the resistance is infinitely large - an open circuit, if close to zero - a short circuit.
Removing the old compressor and preparing the place
The process of removing the old unit requires care, especially if you plan to reuse its housing or protect adjacent elements of the system. First, remove the rear protective panel of the refrigerator. Under it you will see a black barrel - this is motor-compressor.
First, disconnect the electrical contacts. They can be secured with plastic latches or held in place by a tight fit in the terminal block. Be careful not to damage the wires to the relay. After this, you need to bite the copper tubes connecting the compressor to the condenser and evaporator.
⚠️ Attention: When biting off the tubes, residual refrigerant pressure may escape. Although there is little of it in household refrigerators, protect your eyes and ensure the room is ventilated.
When the tubes are disconnected, the compressor is usually supported by four metal studs with rubber shock absorbers. Unscrew the nuts and remove the unit. It is better to immediately clean the installation site from dust and dirt, since carbon deposits and dust they can interfere with the normal vibration decoupling of the new motor.
☑️ Preparation for installation
Connection diagram and color wires
The most critical stage is the electrical connection. Incorrect commutation will result in the engine either not starting or burning out after a few seconds. There are usually markings on the terminal box of a new compressor, but it is better to double-check the diagram. The standard connection diagram includes three main terminals: common, starting and working.
Wires coming from the relay and thermostat are often color-coded, but you cannot rely on color alone, as manufacturers may change standards. Typically, the red wire is responsible for the starting winding, white or black for the working winding, and the yellow-green wire is the ground. But double-checking with a multimeter is required.
The table below shows the contact designations on different types of compressors:
| Designation on the diagram | Winding type | Wire color (standard) | Function |
|---|---|---|---|
| C (Common) | General | Black / White | Network power |
| R (Run) | Working | Red / Brown | Main operation |
| S (Start) | Starting | Blue / Green | Engine start |
| GND | Grounding | Yellow-green | Safety |
If you change a conventional motor to inverter, the circuit will be radically different, since there the control occurs through an electronic module, and not through a classic relay. In this case, you must strictly follow the instructions included with the specific model.
Installing a starting relay and protective thermal contact
The starting relay is a small plastic block that fits onto the side contacts of the compressor. It is he who supplies a short-term impulse to the starting winding to spin the motor shaft. Without a working relay starting the compressor it is impossible.
When installing a new relay, make sure that it sits tightly and until it clicks. Inside it there is a moving contact or posistor, which must be oriented strictly vertically (usually with an upward arrow). If you turn the relay over, gravity will not allow the contact to close, and the motor will only hum.
A protective thermal contact (tablet) is often installed next to the relay. It fits directly onto the compressor housing or is inserted into an open circuit in the power supply. Its task is to break the circuit if the engine temperature exceeds the permissible limit. Do not install a relay without a thermal contactas this will deprive the system of protection against overheating.
⚠️ Attention: Starting relays from different manufacturers (Danfoss, Indesit, Samsung) may have different body geometry. Make sure that you purchase an analogue that is suitable in shape and electrical characteristics.
Soldering contacts and sealing connections
Simply twisting the wires and wrapping them with electrical tape is a gross mistake that will lead to heating and oxidation of the contacts. Soldering must be used for reliable operation. Strip the ends of the wires, tin them with solder and connect them to the relay terminals or adapters.
After soldering, be sure to insulate the connections. Use heat shrink tubing or good quality heat resistant tape. It is important that not a single exposed piece of metal comes into contact with the refrigerator body or the compressor itself, since vibration may damage the insulation over time.
Pay special attention to copper tubes. If you do not have the skills to solder copper pipelines with a torch, it is better to invite a specialist for this stage. Improper soldering of the tubes will lead to a freon leak, and the refrigerator will stop freezing, despite a working motor.
First start-up and performance check
After all the wires are connected and the tubes are sealed, you can proceed to testing. Plug in the refrigerator. In the first seconds, you will hear the characteristic rumble of the engine starting. This is a normal reaction. If after 5-10 seconds a click is heard and the motor stops, there is a problem with the relay or the network voltage.
Check the heating of the compressor. After 15-20 minutes of operation, the motor body should be warm, but not hot. If the temperature is too high, turn off the appliance immediately. Also listen to sounds: metallic knocking or strong vibration indicate mechanical problems or improper fastening.
Make sure that cold begins to be produced. After 30-40 minutes of operation, the inside of the chamber should become noticeably cooler. If the refrigerator works but does not freeze, there may be a freon leak during replacement or a blockage in the system.
Why may a new compressor not start?
There may be several reasons: a faulty start relay, insufficient voltage in the network, an open circuit in the thermostat, or a defect in the new part itself. It is also possible that the overload protection has tripped due to prolonged hand holding during installation.
Is it necessary to vacuum the system when replacing the compressor?
Yes, definitely. When the circuit is opened, air and moisture enter there. Without vacuuming and charging freon with professional equipment, the refrigerator will not work normally.
Is it possible to install a compressor of higher power?
Theoretically, it is possible if the seats and refrigerant match. However, a more powerful motor may not work correctly with the existing evaporator and condenser, which will lead to incomplete evaporation of freon and liquid entering the engine.
How long should the refrigerator sit after replacement?
If the tubes were soldered and refilled with freon, you can turn on the refrigerator immediately after checking for leaks. If you only changed the electrics without opening the circuit, it will take 2-3 hours to stabilize the oil in the crankcase.