Replacement or checking compressor is one of the most difficult procedures in repairing household appliances, requiring not only technical skills, but also strict adherence to electrical safety rules. Unlike other components, this unit is under high pressure and connected to the electrical network, which creates a double danger for an inexperienced technician. That is why the question of how to correctly connect the wires to the compressor from the refrigerator requires a detailed explanation and a step-by-step approach.
The main difficulty lies in identifying the contacts, since the color marking of the wires may vary depending on the manufacturer and year of manufacture of the unit. Incorrect connection of the start relay terminals and the motor windings often leads to a short circuit, burning of a new part, or even fire of the wiring inside the housing. In this article we will analyze the electrical circuit, methods for determining windings and a safe installation algorithm.
⚠️ Attention: All work on connecting the electrical part of the compressor should only be carried out with the refrigerator completely disconnected from the network. The presence of live capacitors can lead to a strong electric shock even after removing the plug from the socket.Design of the electrical part of the compressor
To understand the connection process, you need to clearly understand how the inside of the sealed casing works. It is an asynchronous motor with a squirrel-cage rotor, which has two main working windings: starting and working. These windings come out through three contacts on the compressor housing, which are usually hidden under a protective plastic cap. electric motor inside a sealed casing. It is an asynchronous motor with a squirrel-cage rotor, which has two main working windings: starting and working. These windings exit through three contacts on the compressor housing, which are usually hidden under a protective plastic cap.
A starting relay is connected to these three contacts, which briefly supplies voltage to the starting winding to create torque, and then turns it off. If you mix up the contacts, the engine will hum, but will not start, or will begin to rotate in the opposite direction (depending on the design), which will quickly disable it.
- 🔌 Working winding —has a larger wire cross-section and lower resistance, works constantly during the cooling cycle.
- 🚀 Starting winding —has a smaller cross-section, turns on only at the moment the motor starts.
- ⚡ Common wire —the connection point of the windings where the main network voltage is supplied.
It is important to understand that modern equipment is often equipped with inverter compressors, the connection diagram of which is radically different different from classic models. In such cases, instead of a simple relay, an electronic control unit is used, and direct connection to a 220V network for testing is impossible without special equipment.
What is the difference between inverter compressors when connected?
Inverter models are controlled by complex electronics, which smoothly changes the shaft speed. An attempt to connect them directly to the network, like a regular motor, will instantly burn out the windings or block the system.
Necessary tools and safety measures
Before you begin manipulating the wires, you need to prepare a workbench and tools. You will need not only a standard set of screwdrivers, but also specialized diagnostic tools. The main tool will be multimeter, without which identifying contacts “by eye” is almost impossible and extremely risky.
Insulating materials should also be prepared. The use of ordinary PVC insulating tape near the heating elements of the compressor group is not recommended; it is better to use heat-shrinkable tubes or specialized mica insulation that can withstand high temperatures.
☑️ Preparation for connecting wires
Done: 0 / 5Pay special attention to the condition of the wires themselves. If the insulation at the ends of the cables is cracked or melted, they must be stripped again or extended with new pieces. Poor contact at the junction of the terminal and the wire will lead to local overheating and oxidation.
Tool Purpose Requirements Multimeter Resistance measurement windings Error no more than 2% Pliers Fixation of terminals Dielectric handles Insulation Contact protection Heat resistance up to 105°C Marker Color marking Indelible Contact identification and color marking
The most important stage is determining which wire to connect where. On the case of many modern compressors, such as Embraco or Secop, the contacts already have letter markings under a plastic cover. However, in older models or when replacing a relay with a universal one, you have to rely on resistance measurements.
The standard marking of the terminals on the compressor cover is as follows: the letter
C(Common) indicates the common wire,R(Run) - the working winding, andS(Start) - launcher. In some European models you can find the designationsM(Main) instead of R. The color scheme of relay wires also has its own standards, but you cannot rely only on color, since the previous master could have already made changes.The dialing process begins with a search for a common point. The resistance between the common wire and the working winding is always less than between the common and the starting winding. The resistance between the starting and working windings will be equal to the sum of the two previous values. This is a key physical law that allows you to accurately identify the terminals.
⚠️ Attention: Never apply voltage to the compressor unless you are sure of the integrity of the winding insulation relative to the housing. A breakdown on the housing can lead to an electric shock when touching the metal parts of the refrigerator.Wiring diagram for connecting the wires to the starting relay
After the terminals on the compressor have been identified, it is necessary to correctly connect them to the terminals of the starting relay. The relay has corresponding sockets, which are often also marked with symbols or colors. An error here is unacceptable: if you apply voltage to the starting winding as a working winding, it will burn out in a matter of seconds due to the thin wire.
The connection is made in the following sequence: first, a wire from the network is put on the common contact (through a thermostat), then to the working winding, and lastly, to the starting winding. It is important to ensure that the terminals are tightly seated so that when the vibration of a running motor does not weaken the contact.
- 🔵 Blue or black wire —most often goes to the common point (Common).
- 🟤 Brown or red wire —usually connected to the working winding (Run).
- 🟡 Yellow or white wire —as a rule, leads to the starting winding (Start).
It is worth noting that in some circuits there is a fourth wire that goes to a capacitor or additional protection. Its connection depends on the specific model of the refrigerator, for example Indesit or Atlant may have their own wiring features inside the harness.
📊 What type of compressor are you encountering?Single-phase with relayInverterLinearI don’t know, I need helpChecking the correct connection
Before final assembly and connecting the refrigerator to the network, it is necessary to carry out a control check of the assembled circuit. Visually check that no wires are touching the metal housing of the compressor or the copper pipes of the refrigeration circuit. The gap should be at least 5-10 mm.
Use a multimeter in resistance mode to recheck the circuit from the refrigerator plug to the contacts on the compressor. Make sure that there is no short circuit between any two contacts when the relay is in the off state (although it is difficult to check this on an assembled relay without power supply).
A short-term test run is best done using a wattmeter or current clamp. This will allow you to see the starting current. If the current exceeds the rated current by 5-7 times and does not drop after 2-3 seconds, immediately turn off the power - the compressor does not start, but hums, which indicates an error in connecting the starting winding.
Typical errors and ways to eliminate them
One of the most common mistakes is ignoring the state of the starting relay itself. Even if the wires are connected according to the diagram, a faulty relay with burnt contacts will not allow the compressor to start. Always check the relay for integrity and ease of movement of the moving elements.
Another error is poor twisting or crimping of the terminals. Over time, the place of bad contact begins to heat up, the plastic of the relay melts, and a short circuit occurs. Use a quality tool for crimping the terminals, not just pliers.
If after connecting the compressor works, but the refrigerator does not freeze, the problem may not be in the electrical part, but in the mechanical part or a freon leak. However, if a characteristic hum and clicking is heard, it means that the electrical circuit is assembled correctly, but the engine cannot overcome the pressure in the system.
Is it possible to connect a compressor directly without a relay?
Theoretically, you can start the motor by manually applying voltage to the starting winding, but doing this is categorically not recommended for continuous operation. Without a relay, the starting winding will burn out in a few seconds, since it is not intended for long-term passage of current.
What to do if the colors of the wires do not match the diagram?
The color of the wires in the harnesses of different manufacturers may differ. The only reliable way is to test the windings with a multimeter and determine their resistance, and not focus on the color of the insulation.
Why does the compressor hum, but does not start after replacing the wires?
Most likely, the starting and operating windings are mixed up, or the starting relay is faulty. Also, the cause may be jamming of the mechanical part of the compressor due to lack of oil or freon pressure.
What resistance should be between the windings?
The resistance of the working winding is usually 10-20 Ohms, the starting winding is 30-50 Ohms. The exact values depend on the motor power. The sum of the resistances of the two windings should be equal to the resistance between the extreme contacts.
In conclusion, proper connection of wires to the compressor is the key to the durability of the repair. Take your time, use measuring instruments and carefully check each connection before applying voltage. Following these simple rules will allow you to successfully restore the functionality of the refrigerator and avoid repeated breakdowns.