Repair of household appliances often begins with diagnosing the most important component - the compressor. Refrigerator motor is the heart of the entire cooling system, and its incorrect operation or incorrect connection leads to damage to products. Many owners of household appliances are faced with the need to replace or reconnect the motor after cleaning the contacts or replacing the start-up relay. It is important to understand that the electrical circuit, although simple, requires strict adherence to safety precautions.
Before taking up tools, you need to understand the risks associated with electric current and refrigerant. Hermetic compressor is under high pressure, and the electrical circuit operates from a 220 network volts Installation errors can lead not only to equipment failure, but also to injury. In this article, we will analyze the process in detail, explain the purpose of each wire and help avoid common mistakes made by beginners.
Modern models may differ in the design of the starting equipment, but the basic principle of operation of the electric motor remains unchanged. Asynchronous motor requires correct phasing of the windings to create rotating magnetic field. If the contacts are mixed up, the rotor will not be able to start, and a humming noise will indicate a short circuit or blockage. A competent approach to the task will save time and money, allowing you to restore the operation of the unit without calling a technician.
Diagnostics and preparation for work
The first stage is always a visual inspection and checking the integrity of the windings with a multimeter. Electrical resistance between the contacts should be within certain limits, usually from 10 to 30 Ohms for the working winding and a little higher for the starting winding. If the device shows infinity or zero, this indicates a break or an interturn short circuit, which makes further connection pointless. It is also necessary to make sure that there is no breakdown on the housing, otherwise the use of the equipment will become life-threatening.
During the preparation process, the contact groups should be cleaned of oxides and carbon deposits. Often the cause of failure is not the motor itself, but burnt contacts in starting relay or the thermal relay. Carefully remove the plastic casing protecting the electrical part and inspect the wires for melted insulation. If the insulation has become hard and cracked, it must be replaced, since the heating during compressor operation is significant.
⚠️ Attention: Before starting any work, be sure to disconnect the refrigerator from the power supply and wait until the capacitors are discharged, if they are present in the control circuit.
For high-quality diagnostics, you will need a set of tools, including a multimeter, pliers, screwdrivers and, possibly, new connecting terminals. Do not neglect checking the voltage in the network, as unstable parameters can cause a second breakdown immediately after repair. Starting current the engine at the time of starting is significantly higher than the operating voltage, which creates an additional load on the wiring.
Identification of winding contacts
On The motor terminal block usually has three or four terminals, the purpose of which must be clearly identified. Standard markings may be letters or color codes, but in older models these marks are often erased. Working winding (Running) has less resistance than Starting, which is a key feature for distinguishing them. The third contact is always Common, to which one of the phase wires is connected.
The dialing process takes a few minutes, but requires care. Apply the multimeter probes to the pairs of contacts and record the resulting resistance values. The largest value will be between the starting and operating windings, and the sum of the resistances of the other two pairs should be equal to this value. This is a basic law of physics that allows you to accurately determine common wire even without a diagram.
In some refrigerator models, especially imported ones, the color marking of the wires may differ from domestic standards. For example, a red wire often indicates a working winding, and a blue or black wire often indicates a starting winding, but you cannot rely on color alone. Always double-check the data with a multimeter, since the previous repairman may have already made changes to the wiring. Accurate determination of the common contact is critically important, since applying voltage to it and the starting winding without a working one will lead to the motor burning out.
- 🔌 Common contact (C): the connection point of both windings, the phase wire of the network is connected to it.
- ⚙️ Working winding (R): has less resistance, provides the main rotation of the rotor.
- 🚀 Start winding (S): has greater resistance, creates the initial impulse for start.
- ⚡ Grounding: a separate screw or contact on the case for connecting the grounding conductor.
Starting relay connection diagram
The starting relay is an automatic switch that supplies voltage to the starting winding only in moment of engine start. As soon as the rotor picks up speed, the current in the circuit drops and the relay opens the contacts, turning off the starting winding. The connection diagram depends on the type of relay: it can be inductive (old style) or posistor (modern). In induction relay a current coil is used, which at start draws in the core and closes the contacts.
Posistor relays work on the principle of changing the resistance of a ceramic element when heated. In a cold state, the resistance of the posistor is low, and current flows freely through the starting winding. When heated by passing current, the resistance increases sharply, actually breaking the circuit. Such a system is more reliable and does not require precise orientation in space, unlike induction analogues, which are position sensitive.
When connecting, it is important to observe the orientation of the relay on the motor block. The body of the product often has an "UP" arrow or lettering indicating the up position. If the relay is installed incorrectly, the contacts may not open after start, which will lead to an overload and tripping of the thermal relay or burnout of the windings. Thermal relay also plays an important role by opening the circuit when the compressor overheats.
Operating principle posistor
A posistor is a semiconductor element whose resistance depends on temperature. When the refrigerator is turned on, the posistor is cold and has low resistance, passing current to the starting winding. Literally after 1-3 seconds it heats up to the Curie point, its resistance increases abruptly to several megaohms, and the current through the starting winding practically stops. It cools down for about 2-3 minutes, so after turning off the refrigerator, restarting is possible only after this period of time.
| Relay type | Principle of operation | Sensitivity to position | Cycle life |
|---|---|---|---|
| Induction | Electromagnetic retraction | High (vertical only) | Medium |
| Posistor | Temperature change resistance | Low (any orientation) | High |
| Electronic | Key (transistor) control | Absent | Very high |
Wire connection process
Direct connection of wires requires the use of high-quality materials that can withstand vibration and heat. Twists in this case are categorically not recommended, as they oxidize and heat up over time. It is best to use crimp terminals or special connectors that ensure tight contact. Copper wire must be stripped to a length sufficient to fully enter the terminal, but no more.
When assembling an electrical circuit, make sure that the wires do not touch the metal parts of the housing compressor or refrigeration pipes. The vibration of a running unit can grind the insulation, which will lead to a short circuit to the housing. To fix the harness, use plastic clamps, but do not tighten them too much so as not to damage the insulation. Insulating materials must be heat-resistant, withstanding temperatures up to 100 degrees Celsius.
After physically connecting all contacts, check the circuit again. Make sure that the phase wire goes to the common contact through the thermal relay, and the neutral wire goes directly to the motor (or through a relay, depending on the circuit). An error in connecting phase and zero in household single-phase networks may not affect the operation of the motor, but violates the electrical safety rules and the logic of the operation of protective devices.
☑️ Check before turning on
First launch and testing
The moment of truth comes when you turn it on for the first time after repair. Connect the refrigerator to the network through a working socket with grounding. In the first seconds, you will hear the characteristic hum of the engine starting. Starting current this may cause a short-term drop in voltage in the network, which is normal. If the compressor hums but does not start within 3-5 seconds, immediately turn off the power - this is a sign of a jammed or faulty starter.
Successful startup is characterized by a smooth, quiet hum and gradual cooling of the condenser (grid at the back of the refrigerator). After 10-15 minutes of operation, check the temperature of the motor housing: it should be warm, but not hot. If there is strong heating in the winding area or a burning smell appears, operation should be stopped. Thermal relay In such a situation, it may not have time to operate if it is faulty.
Also pay attention to the cyclic operation. The engine should run for a certain time, then turn off and rest. If your refrigerator runs non-stop, it may indicate a freon leak or a malfunctioning thermostat rather than an electrical problem. In this case, the connection is correct, but diagnostics of the refrigeration circuit is required.
⚠️ Attention: If the circuit breaker in the panel is knocked out during startup, this indicates a short circuit in the circuit or a breakdown of the windings to the housing. Restart without eliminating the cause