The relay in the refrigerator is a key element responsible for turning the compressor on and off depending on the temperature in the chamber. If the device fails or needs to be replaced, it is important to connect correctly to avoid breakdowns or emergency situations. In this article we will look in detail at how to connect a relay in different types of refrigerators, what tools will be needed and what to pay attention to when working.
A faulty relay can lead to constant operation of the compressor, overheating, increased energy consumption, or, conversely, to a lack of cooling. However, not all breakdowns require calling a specialist - many operations can be performed independently if you follow the instructions and observe safety precautions. Below you will find step-by-step recommendations, connection diagrams and answers to frequently asked questions.
Types of relays in refrigerators and their purpose
Before you start connecting, you need to determine what type of relay is installed in your refrigerator. The installation diagram and configuration features depend on this. Main types:
- 🔧 Thermal control relay (thermostat) - responsible for maintaining the set temperature. Usually located inside the chamber or on the rear panel.
- ⚡ Start-protective relay —ensures the start of the compressor and protects it from overloads. Installed next to the compressor.
- 🔄 Time relay (in No Frost systems) - controls the operation of the fan and heater for defrosting.
In most household refrigerators (Atlant, Indesit, Samsung, LG) a combination of a thermostatic and start-up relay is used. For example, in models Atlant MXM-1708 or Indesit DF 4180 the thermostat is located in the upper part of the chamber, and the start relay is on the compressor. In systems No Frost (for example, Samsung RB-30 J3200), a time relay is additionally installed to control the defrosting cycle.
If you are not sure of the type of relay, pay attention to its appearance and markings. The start-up relay is usually a small plastic box with terminals connected to the compressor, and the thermostat has a capillary tube and a temperature scale.
Tools and materials for connection
To connect the relay yourself, you will need a minimum set of tools. Some of them are in every home, others can be purchased at an electronics store:
- 🔧 Phillips and flathead screwdrivers (for dismantling the panel and fasteners).
- 🔌 Multimeter (for checking the circuit and voltage).
- 🔨 Pliers or wire cutters (for working with wires).
- 🔗 Insulating tape or heat shrink tube (to insulate connections).
- 📏 Set of wrenches (if dismantling of the compressor is required).
Also prepare a relay connection diagram for your refrigerator model. It can be found in the operating instructions or on the compressor nameplate. If the documentation is lost, look for a diagram on the Internet based on the refrigerator model or compressor type (for example, Embraco EGX 90HLC or Secop (Danfoss) NL 6LX).
⚠️ Attention: Before starting work, be sure to disconnect the refrigerator from the network and discharge the compressor capacitor by shorting its terminals with a screwdriver with an insulated handle. This will prevent electric shock current.
If you replace the relay with a new one, make sure that its parameters (voltage, current, mounting type) correspond to the original. For example, for compressors Embraco start-up protection relays of the series PTC or POSare often used, and for Secop — relay 3TS.
Connection diagram of the start-up protection relay
The start-up protection relay is connected directly to the compressor and ensures its startup and protection from overloads. The typical connection diagram includes three main contacts:
- Common (C) —connects to the mains phase.
- Start (Start, S) —connected to the starting winding of the compressor.
- Working (Run, R) —connected to the working winding.
Below is a table with pinouts for popular types of relays and compressors:
| Relay type | Compressor | Terminal designation | Wire color (standard) |
|---|---|---|---|
| PTC (Embraco) | Embraco EGX, EMB | C (Common), S (Start), R (Run) | Black (C), White (S), Red (R) |
| POS (Secop) | Secop (Danfoss) NL, NF | L (Line), S (Start), M (Main) | Brown (L), Yellow (S), Blue (M) |
| 3TS (universal) | Any | 1 (Common), 2 (Start), 3 (Run) | Depends on the model |
Before connecting, take a photo of the original circuit or mark the wires so as not to mix them up when reassembling. If the relay is connected through a terminal block, use a screwdriver to tighten the contacts - a weak contact can lead to heating and melting of the plastic housing of the relay.
Disconnect the refrigerator from the network|Take a photo of the original circuit|Mark the wires|Check the integrity of the new relay with a multimeter-->
Connecting the thermostatic relay (thermostat)
The thermostat is responsible for maintaining the set temperature in the refrigeration chamber. Its connection is somewhat more complicated, as it requires working with it. capillary tube and setting the temperature mode. Main steps:
- Removing the old relay. Usually the thermostat is mounted on screws or latches inside the chamber. Carefully remove the plastic panel, disconnect the wires and remove the capillary tube from the mount.
- Installing a new one relay. Connect the wires according to the diagram (usually on the thermostat body there are terminal markings:
3— common,4— to the compressor,6—to the lighting lamp). - Fastening the capillary tube. The tube should fit tightly to the evaporator, but not be pinched. Use original fasteners or electrical tape.
- Setting the temperature. After connecting, set the thermostat control to the middle position and check the operation of the refrigerator.
In refrigerators with electronic control (for example, LG GA-B489 YDQZ or Samsung RT-40), instead of a mechanical thermostat, a temperature sensor and an electronic board are used. In this case, replacing the relay requires soldering work or programming the module, which is best left to a specialist.
⚠️ Attention: If after replacing the thermostat the refrigerator does not turn on or runs without stopping, check the integrity of the capillary tube. Damage to the tube (kink, rupture) will lead to incorrect operation of the device.
To check the functionality of the thermostat, use a multimeter in dial mode. When rotating the regulator from the minimum to maximum position, the contacts must be turned on. close and open. If this does not happen, the relay is faulty.
How to check the thermostat without dismantling?
If the refrigerator does not turn on, try shorting the wires going to the terminals 3 and 4 thermostat (common and compressor). If the compressor starts working, the problem is in the thermal relay. Do not leave the wires closed for a long time - this can lead to overheating!
Features of connecting relays in No Frost refrigerators
In systems No Frost in addition to standard relays are used time relay (defrost timer) and fan relay. These devices control the defrost cycle and the operation of the air flow. Connecting such relays has its own nuances:
- ⏱️ The time relay usually connected to the heating element. (heating element) and the fan. Its replacement requires strict adherence to the sequence of wires, since incorrect connection can damage the heating element.
- 🌀 Fan relay is often integrated into the control board (Samsung RL-34) it is replaced along with the module.
Example of a time relay connection diagram in the system No Frost:
Defrost timer:
- Terminal 1 → Power 220V
- Terminal 2 → Heater (heater)
- Terminal 3 → Fan
- Terminal 4 → Compressor (via thermostat)
If your refrigerator has an electronic control module (for example, in models LG Inverter Linear), replacing the relay may require flashing the board. In this case, it is recommended to contact a service center.
Checking the operation of the relay after connecting
After connecting the relay, you need to check the correct operation of the refrigerator. Follow this algorithm:
- Connect the refrigerator to the network and set the average temperature on the thermostat.
- Listen to the compressor: it should turn on in 5-10 minutes. If the compressor does not start, check the connection of the start relay.
- Measure the temperature in the chamber after 2-3 hours. It should correspond to the specified value (usually +4...+5°C in the refrigerator compartment).
- Make sure that the compressor is turned off periodically (the work/rest cycle should be approximately 1:1).
If the refrigerator runs continuously or does not cool, the following problems are possible:
- 🔌 Incorrect connection wires to the relay.
- 🌡️ Malfunction of the thermostat or temperature sensor.
- ❄️ Refrigerant leak (refill required).
- 🔋 Compressor malfunction (needs diagnostics).
For diagnostics, use a multimeter:
- Check the voltage at the compressor terminals (should be ~220V when turned on).
- Ring the compressor windings (the resistance of the working winding is usually 10–30 Ohms, the starting winding is 20–50 Ohms).
- Make sure that the relay contacts close when the set temperature is reached.
Frequent errors when connecting a relay
Even experienced craftsmen sometimes make mistakes when replacing a relay. Here are the most common of them and ways to avoid them:
- 🔀 Mixed-up wires. For example, connecting the starting winding instead of the working winding will lead to the compressor not starting or operating with overheating. Always label the wires before disconnecting!
- 🔌 Weak contact. Poorly tightened terminals can cause sparking and melting of the relay housing. Use pliers to securely fix.
- 🌡️ Incorrect installation of the capillary tube. If the thermostat tube touches the chamber walls or is pinched, the temperature reading will be incorrect.
- ⚡ Ignoring multimeter testing. Always test a new relay before installation to eliminate manufacturing defects.
Another typical mistake is using a relay with inappropriate parameters. For example, if a relay is installed in a refrigerator with a compressor, the starting current may be insufficient and the compressor will not start. Always check the markings on the relay and compressor housing. Embraco EGX 90HLC install relay for Secop NL 6LX, the starting current may be insufficient and the compressor will not start. Always check the markings on the relay and compressor housings.
Critical: in refrigerators with inverter compressors (for example, LG Inverter Linear or Hitachi R-VG430PUC6) you cannot use standard start-up relays. Electronic control modules are used here, and replacement requires special equipment.
FAQ: Answers to frequently asked questions
Is it possible to connect a relay without a soldering iron?
Yes, in most cases the relay is connected via terminal blocks or screw terminals. A soldering iron may only be needed when repairing the control board in refrigerators with an electronic thermostat.
How to determine that the relay has burned out and not the compressor?
If you hear a click when you turn on the refrigerator, but the compressor does not start, most likely the problem is in the start relay. If the compressor hums but does not rotate, or the protection is triggered after a few seconds, the compressor itself is faulty. For an accurate diagnosis, check the resistance of the windings with a multimeter.
What to do if, after replacing the relay, the refrigerator freezes too much?
This may be caused by incorrect settings of the thermostat or damage to the capillary tube. Check the position of the temperature regulator and the integrity of the tube. If the problem persists, the thermostat itself may be faulty.
Can I use a relay from another refrigerator?
Only if their technical parameters (voltage, current, compressor type) are completely the same. For example, a relay from Atlant may be suitable for Indesitif both refrigerators are equipped with compressors Embraco of the same series. Always check the markings!
Do you need to discharge the capacitor before work?
Yes, this is a must! The compressor capacitor can retain its charge even after the refrigerator is unplugged. To discharge it, short the terminals with an insulated screwdriver. Do not touch the condenser with your bare hands!