Start-up relays are used to facilitate starting the refrigerator compressor motor. They also perform the function of protecting the motor from overheating, periodically turning it off. Like other parts and components of the refrigerator, they can fail. The home master can independently determine the malfunction and replace such a part.
Reasons for the failure of the refrigerator relay
Units such as a motor-compressor and an evaporator should not be repaired by yourself. If you understand electrical engineering, you can try to save money and time by contacting a service center and replace the start-up protection relay of your refrigerator by yourself.
A relay is a fairly simple device, and there are few reasons for its failure:
- Jamming of the movable contact group. In this case, the contacts do not close the circuit. Or, conversely, do not open it.
- Failure (burnout) of the heating winding
- Loss of elasticity of a bimetallic plate.
Externally, a device malfunction manifests itself as follows:
- Compressor engine does not start.
- The engine runs for a while, usually no more than 10 minutes, and then stops.
- The engine starts to work, but does not turn off, although the set freezer temperature and the refrigerator has already been reached.
To determine what exactly the relay failed, it is recommended to disconnect the terminals from it and connect them directly to the engine. If it worked, it was a relay.
Another diagnostic method is to connect a known-good device. If the engine started up normally, with periodic shutdowns in 10-20 minutes, then the serviceable device can simply be left in place. The cost of the part for the most common brands is in the range of 500-1000 rubles.
Similar symptoms are observed in the event of a coolant leak, which complicates the diagnosis.
Before you start to remove the device from the refrigerator, it is worth checking a few more points.
- Traces of burning or fusion of wires and connectors are visible. Such a device is subject to unconditional replacement.
- The device is loose. In this case, the movable contact groups may jam. In this case, the motor begins to vibrate. Tighten or replace the fasteners.
- Loose connectors. Contacts should be cleaned and pinched.
If during self-diagnosis and repair it was not possible to achieve success, you should not try to disassemble the components of the refrigerator, especially the motor-compressor. It is better to contact a service center.
Types of start-up relays
Despite the variety of external design, modern refrigerators use two main types of start-up relay:
- Current Triggered upon reaching a certain value of the flowing current. A normally working motor consumes a given current. When the motor overheats, the current consumption increases sharply, the device trips and breaks the circuit, turning off the motor. After the motor cools down, the device resumes its operation.
- Thermal current. They work both upon reaching the current value and upon reaching the set temperature. While the engine consumes normal current, the spiral through which it passes is subject to slight heat and does not affect the bimetal plate. The higher the passing current, the more the coil heats up.It heats the sensitive plate, it changes its shape so much that it leads to the opening of the contacts through which the electric motor is powered.
Appearance of various models
In current-thermal devices, an increase in temperature leads to a change in the shape of the bimetallic plate. It is welded from two plates, the metals of which have a different coefficient of thermal expansion. When heated, the bimetallic plate bends and opens the contact group, turning off the electric motor. After the engine has cooled, the plate returns to its original shape and closes the contact groups, starting the engine again. In addition to the thermal protection circuit, the engine turns on and off as well with a thermostat.
The plate is heated in various ways:
- direct - heating is carried out by a flowing current;
- indirect - a separate spiral heater is used.
The start-up device also performs the function of starting the electric motor. To do this, for a short time, a large starting current is applied to the motor winding, and after the rotor starts moving and starts to rotate, the current decreases to operating values.
Externally, the device looks like a small box mounted on a compressor casing.
The appearance of the induction relay
Devices may have:
- Two contacts - phase 220 volts and Earth. It is applied on synchronous electric motors.
- Three contacts: starting winding, working winding and Earth. Such designs are used on asynchronous electric motors.
The contacts are distinguished by the color of the cables passing to them.
DXR type induction relays are mounted on the refrigerator frame and are designed to control DXM type motor compressors. To increase the speed of operation and shutdown of the engine, a strong permanent magnet is placed next to the plate. When the plate, bending under the influence of heat, enters the magnet attraction zone, it attracts it, accelerating the response. Magnet pull also gives extra time to cool an overheated motor. The cooled plate overcomes the attraction of the magnet and closes the contacts.
Relays of the RTP type are characterized by a lower tripping current and smaller dimensions. It does not require fixing on the frame and is mounted directly on the wires.
You can check the functionality of the start-up relay using an ohmmeter, multimeter or other available measuring device. A working device has zero resistance between the contacts. If the resistance is infinite, the device is malfunctioning and needs to be changed.
The start-up protection device operates in a single electrical circuit with a temperature controller.
Electric circuit
The refrigerator user manual indicates which appliances can be used for each particular model. This allows you to choose the right device to replace if the exact same ones that are out of order are unavailable.
How to remove a relay from a refrigerator
Before starting any repair work, make sure that the refrigerator is unplugged and the plug is unplugged. Failure to observe this precaution could result in severe electric shock.
RTP relays are removed by simply disconnecting the contacts. If the refrigerator is not new, the contacts may oxidize and “stick” in this case, you should pick them up in the connector with a thin flat screwdriver, screw them, and then gradually move the connector until the contact plate comes out completely.
To remove a part from the refrigerator, you must first determine how to install it. The following methods are used:
- on screws;
- on rivets;
- on latches.
The connectors are disconnected first. Next, the relay mounting screws are unscrewed. If the device is fixed with rivets, they should be carefully drilled at low revolutions of the drill or screwdriver. Experts recommend fastening the new device to the screws.
Important! Mark the wires immediately after disconnecting the contacts.This is especially important on older refrigerators, where wires may darken over time or change color.
The latches are pressed with a flat screwdriver until the relay is released. In this case, care must be taken, especially on older refrigerators, since over time the plastic latches become brittle.
How to replace the relay in the refrigerator (replacement procedure in different models)
Nord, Ariston, Indesit, Stinol
Refrigerators of these brands have a similar design. Replacement is best done in the following order:
- disconnect the plug from the outlet;
- unscrew the screw securing the hose to the rear panel;
- unscrew the screws securing the rear panel of the motor;
Dismantling Nord, Ariston, Indesit, Stinol
- remove the panel and push it;
- using pliers or pliers, depress the relay latches;
Latch release
- remove the defective part;
- disconnect the contacts and mark the wires.
Disconnecting Contacts
Next, you need to take a working device and install, following the reverse procedure.
Atlant and Minsk
These popular brands are produced at the same factory and have a similar device.
To remove the relay on Atlant or Minsk brand refrigerators:
- Make sure that the device is disconnected from the mains.
- Carefully remove the wire clip holding the relay.
- Remove contacts
- Mark the wires. This will help not to confuse them during assembly, especially on older refrigerators with darkened or discolored wires.
- Unscrew the screws securing the relays to the motor - compressor housing.
- Remove the device by depressing the wire clip.
Dismantling Atlant, Minsk
A working relay is mounted in this order:
- Install the device on the motor-compressor housing.
- Screw it on while securing the bracket securely.
- Connect the wires in accordance with the marking made during dismantling.
- Replace the wire clip.
Liebherr
Refrigerators of this brand are highly reliable, but, nevertheless, the start-up relay failure also happens. Typical causes of failure:
- overheating of the spiral;
- loss of flexibility of the bimetallic plate;
- jamming of the contact group.
Due to the high cost of components, you can try to diagnose these malfunctions yourself. The relay on Liebherr refrigerators is mounted next to the motor compressor and is accessible directly from the rear wall.
If you remove the plastic cover, you can inspect the details of the device. Contact groups can be cleaned with fine sandpaper. You should also check the serviceability of the return spring.
Removing Liebherr Relays
If the device did not work after stripping the contacts, unscrew the fastening screws located in the corners of the device, disconnect the supply wires and replace the relay. The new relay must be installed in exactly the same position as the old one. Violation of orientation will lead to the fact that the contacts will not go down under the action of gravity.
If you are not confident in your knowledge of electrical engineering, it is better not to risk it and still call a master. The cost of repairs in the service center, as a rule, is still lower than the price of the entire refrigerator.
