Sudden stop of the compressor or its convulsive attempts to start with a characteristic click often indicate a failure of the trigger mechanism. It is this small element that is responsible for supplying voltage to the motor windings at the moment of start. Owners of refrigerators Nord, Nord Frost and Nord T face this problem regularly, since the life of the contact group is limited by switching on and off cycles.
Replacing the relay yourself is a real opportunity to save on calling a technician if you have basic skills in working with power tools. However, it is important to understand that safety comes first, since we work with high voltage. Before proceeding with dismantling, it is necessary to clearly understand the design of the unit and the principle of its operation so as not to damage other components of the system.
In this instruction we will analyze in detail the process of diagnosing, selecting and installing a new start relay on the compressor of a Nord brand refrigerator. You will learn how to distinguish a burnt part from a malfunction of the motor itself, what tools you will need and how to avoid common mistakes during assembly. Carefully following the algorithm of actions will help return the equipment to cold as soon as possible.
Fault diagnosis and signs of breakdown
The first sign that start relay has failed is a characteristic sound. The refrigerator hums but does not start, or there is a loud click followed by silence. In some cases, the compressor may jerk, trying to start, but immediately turn off due to thermal protection. This indicates that the circuit is not closing properly.
Visual inspection can also provide important clues. If traces of burning, melted plastic or soot are visible on the relay body, then replacement is inevitable. Often inside the case you can see a destroyed coil or burnt contacts, which makes further operation of the part impossible. Sometimes the problem lies not in the relay itself, but in the oxidation of the contacts on the compressor terminals.
> ⚠️ Attention: If after replacing the relay the refrigerator does not start again or the machine in the panel knocks out, immediately stop trying to turn it on. This may indicate an interturn short circuit in the compressor windings or a breakdown to the housing, which requires professional diagnostics.
For accurate diagnostics, you can use a multimeter. By ringing the contacts, you can determine the presence of a break or short circuit in the coil. The resistance of a working coil is usually several tens of ohms, while a break will show infinity. It is also worth checking the thermal relay, which is often built into the same housing as the starting one, for conductivity in a cold state.
Selection of a suitable relay for the Nord model
Nord refrigerators are equipped with compressors from various manufacturers, including themselves Nord, as well as units from Danfoss (now Secop), Atlant or Lg. Therefore, there is no universal solution, and relays must be selected strictly according to markings or parameters. There is always a code on the body of an old part, for example PTM-11C, CSR-35 or RKT with a digital index.
If the marking is erased or unreadable, you need to focus on the engine power and type of refrigerant. Relays for R134a and R600a may be structurally different, although the operating principle is similar. It is also important to consider the location of the contacts: they can be located at the bottom, on the side, or have a specific block shape, which should perfectly match the compressor connectors.
The table below will help you navigate the main types of relays found in equipment of this brand:
| Relay type | Marking | Compatibility | Features |
|---|---|---|---|
| Posistor | PTM, PTC | Compressors up to 250 W | Works silently, no moving contacts |
| Induction | RKT, RTP | Powerful motors | Has a movable core and contacts |
| Combined | With thermal | Most Nord models | Overheat protection built into the case |
| Universal | Series 117 | Replacing analogues | Requires careful switching of wires |
When purchasing a new part, pay attention to the build quality. Cheap Chinese analogues may not have cut-off current calibration, which will lead to rapid failure of the new compressor. It is better to purchase original spare parts or certified analogues from well-known brands, such as Danfoss or Indesit.
Necessary tools and workplace preparation
To carry out the work, you will need a minimum set of tools that can be found in every home. The main tool will be screwdriver (usually a cross and a flat one) for removing the back panel and clamps. You will also need pliers or pliers for working with wires and clamps, and in some cases, side cutters.
Be sure to prepare a multimeter to test the circuit before assembly. It will be a good idea to have electrical tape or heat shrink on hand if you need to restore the insulation of the wires. The workplace should be well lit, since the space behind the refrigerator and around the compressor is often dark and dusty.
☑️ Ready for repair
Before starting any manipulations, the refrigerator must be completely defrosted and dried. Moisture inside the chambers or on the floor can cause a short circuit. You should also move the unit away from the wall, providing free access to the rear wall from all sides.
Step-by-step instructions for replacing the relay
The replacement process begins by completely disconnecting the device from the power supply. Unplug the plug from the socket - this critically important is for your safety. Remove the rear metal panel that covers the compressor compartment. It is usually attached to four screws around the perimeter that need to be unscrewed.
When you get to the compressor, you will see a black cylindrical or pear-shaped element with wires going to it. This is the starting relay along with a thermal protector. Carefully remove the retaining clip or bracket, if present. Then, by gently rocking from side to side, remove the relay from the three pins of the compressor. Do not use excessive force to avoid breaking the plastic connectors or contacts.
Wire connection diagram
Typically, a relay has three main contacts: S (Start), R (Run) and C (Common). The wires from the thermal relay go to pin R, and power is supplied to C. Mixing up pins S and R will result in a hum, but starting will be impossible, or the winding will burn out.
Install the new part, making sure it fits tightly onto the pins. The orientation should be exactly the same as the old relay (usually the "UP" marking points toward the top). Put on the retaining clip and connect the wires to the terminals, following the color code or diagram if you disconnected them. Assemble the protective panel and turn on the refrigerator.
> ⚠️ Attention: If you are installing a universal relay, carefully study the diagram on its body. Incorrect connection of phase and zero to the contacts of the starting and operating windings can lead to instantaneous combustion of the new part.
Typical mistakes and how to avoid them
One of the most common mistakes is ignoring the condition of the compressor itself. Installing a new relay on a jammed motor will not work and will only lead to repeated failure of the spare part. Before replacing, always check the resistance of the windings: the sum of the resistances of the starting and operating windings should be equal to the resistance between the extreme contacts.
Another common mistake is incorrect orientation of the relay. Some models only work in a certain position relative to the horizon, since a movable core or ball may be used inside. If you place the relay upside down, gravity will not allow the contacts to close or open at the right time.
Also, do not neglect cleaning the contacts. Oxidation on the compressor pins can simulate a relay failure. Clean them with fine sandpaper or a file before installing the new part. This will ensure reliable contact and extend the service life of the equipment.
Checking operation after installation
After assembly, turn on the refrigerator and listen. Startup should be smooth, without loud clicks or buzzing. The compressor should pick up speed within 1-3 seconds. If you hear only a hum and after a few seconds you hear a shutdown click, then the problem is not solved. In this case, it is necessary to re-check the connection diagram and the integrity of the wires.
It is important to monitor the temperature of the condenser (black grille at the back) in the first minutes of operation. If it begins to heat up evenly, it means that the refrigerant is circulating and the compressor is working under load. If the grille remains cold and the motor is humming, there may be a problem in the electrical circuit or a problem in the mechanics of the motor.
During the first hour of operation, periodically check the temperature of the relay housing. It should not heat up to the point where it is impossible to touch it with your hand. Excessive heating indicates poor contact or a mismatch between the parameters of the engine power part.
Frequently asked questions (FAQ)
Is it possible to start a Nord refrigerator without a relay?
Theoretically, you can start the motor by applying voltage directly to the working winding, and closing the start winding through the button only at the moment of start. However, this dangerous requires the skills of an electrician. Without a relay, the compressor will not be able to operate in automatic mode and will quickly burn out. Operation without a relay is impossible.
Why did the new relay burn out after a week?
There may be several reasons: power surges in the network, jamming of the compressor piston group, incorrect installation (wrong orientation) or a defective part. Also, frequent switching on/off (for example, due to a faulty thermostat) reduces the service life of the contacts.
Where can you find the relay markings if they are erased?
If the markings are not readable, you will have to select an analogue based on the compressor power (indicated on the nameplate of the motor itself, for example, 1/5 HP or 1/4 HP) and type of refrigerant. It is best to take the old relay with you to the store or photograph its shape and contact arrangement for comparison.
What is the difference between the relay for R134a and R600a?
The main difference is often the current characteristics and design. R600a (isobutane) requires a more explosion-proof design and often lower inrush current. Relays for different freons may have different markings and are not always interchangeable without recalculating the parameters.