A sudden stop of the compressor or a characteristic clicking sound when trying to start the refrigerator often indicates a malfunction of the start-up relay. It is this small but critical element that is responsible for supplying voltage to the motor windings and protecting it from overloads. Owners of household appliances are often faced with the need for a visual inspection or complete replacement of this component, which requires careful dismantling of the protective casing.
The procedure for removing the cover does not require complex professional equipment, but it requires adherence to strict safety measures and an understanding of the unit's structure. Incorrect actions can lead to damaged contacts, loss of system seals, or even electric shock. Before starting work, you need to clearly understand where the relay is located and how it is attached to the compressor housing.
In this article we will analyze in detail the algorithm of actions, the necessary tools and typical mistakes made during self-repair. You'll learn how to identify your relay type, properly disconnect the wires, and safely remove the part for further diagnosis. Following the sequence of operations will avoid additional breakdowns and save time.
Fault diagnosis and signs of relay failure
Before disassembling the equipment, you should make sure that the problem lies in the starting device. Start relay is an electromechanical switch that supplies current to the starting device compressor winding only at the moment of startup. If this mechanism fails, the compressor either hums but does not start, or makes periodic clicks at intervals of several seconds.
One of the obvious signs of a malfunction is the strong heating of the compressor housing when the motor is not running. This happens because the engine is trying to start, consuming a huge starting current, but due to the lack of switching in the relay, it does not go into operating mode. In such a situation, the thermal protection is triggered, opening the circuit, after which the cycle is repeated again after some time.
It is also worth paying attention to the appearance of the part, if it is possible to visually inspect it without completely dismantling it. Carbon deposits on the contacts, melted plastic, or the presence of a characteristic burning smell inside the relay housing indicate that the element requires replacement. Sometimes the problem can be identified by simply shaking the removed relay: if a knock is heard inside, it means the mechanical part or core is damaged.
Necessary tools and safety measures
Working with electrical appliances, especially those under high voltage, requires strict adherence to electrical safety rules. The first and most important step is to completely disconnect the refrigerator from the electrical network. It is not enough to simply turn it off with a button; you need to remove the plug from the socket to eliminate the risk of accidental voltage supply during the repair process.
To carry out the work, you will need a minimum set of tools, which is usually in the arsenal of a home craftsman. The main tool will be a flathead and Phillips screwdriver, which are necessary to remove fasteners and the compressor cover. You may also need pliers with insulated handles for working with wires and contacts.
- 🛠️ Screwdrivers (flat and Phillips) for dismantling the casing and terminals.
- 🔦 Flashlight for illuminating the working area in the compressor niche.
- 📸 Smartphone or a camera for photographing the wiring diagram.
- 🧤 Dielectric gloves for additional hand protection.
It is important to ensure good lighting of the work area, since the space behind the back wall of the refrigerator is often dark. If you work in a garage or workshop, use a portable lamp. If you do not have experience working with electricity, it is better to enlist the help of a more experienced assistant.
Access to the compressor and removal of the protective casing
The start relay is always located directly on the compressor housing, which is usually located at the lower rear of the refrigeration unit. To get to it, you need to move the refrigerator away from the wall, providing free access from all sides. Be careful not to damage the floor or pinch the copper tubes going to the condenser.
On most modern models, the compressor is covered with a metal or plastic casing, which protects the mechanism from dust and accidental damage. It can be secured with latches or screws. If you see screws around the perimeter of the lid, carefully unscrew them, being careful not to drop them into hard-to-reach places behind the refrigerator.
In models with latches, you need to find the latches and carefully press them out with a flat-head screwdriver. Do not use excessive force as the plastic becomes brittle over time and may crack. After removing the fasteners, the casing is removed by moving downwards or to the side, providing access to the motor and attachments.
⚠️ Attention: Before removing the casing, make sure that the condenser (black grille at the back) has cooled down if the refrigerator has been running before. Touching hot elements can cause burns, and a sharp temperature change during cleaning can damage the tubes.
After removing the protective cover, you will see a view of the compressor, to the back or side of which a small plastic box is attached. This is the start relay housing. It can be black, white or gray, depending on the manufacturer and year of manufacture of the equipment.
The process of dismantling the relay cover and disconnecting the wires
Itself trigger mechanism is enclosed in a plastic case, which is attached directly to the compressor terminals or fixed with a clamp. To remove the cover, you first need to disconnect the wires going to the contact group. It is extremely important not to act at random here.
Use a previously prepared smartphone to take several high-quality photographs of connecting the wires from different angles. This will help you properly restore the connection after repairing or replacing a part. Remember or write down which wire of which color is connected to which contact.
☑️ Procedure for disconnecting the relay
The wire terminals are usually removed by hand or using pliers if they are very tight. Do not pull on the wires themselves; hold onto the plastic tip of the terminal so as not to break the wire. After disconnecting all the wires, you can begin to remove the relay body itself.
The relay body often consists of two halves connected by plastic latches. To remove the top cover (or separate the halves), you need to carefully pry the joint with a flat-head screwdriver. Move around the perimeter, gradually unsnapping the latches. Inside you will see an inductor, contacts and, possibly, a posistor (in models with a posistor start).
If the relay is mounted on three pins of the compressor, you just need to pull it down, swinging it slightly from side to side. It is removed along with the cover. Disassembly of the plastic box itself is required only to replace the insides or detailed cleaning of the contacts, which in modern conditions is often impractical.
Types of relays and their design features
Understanding the type of your relay will help you correctly interpret what you see inside the case. There are two main types of starting devices used in household appliances: induction (electromagnetic) and posistor. They have fundamental differences in design and principle of operation.
Induction relays operate using an electromagnetic coil, which, when a starting current passes, draws in the core, closing the contacts of the starting winding. When the engine picks up speed, the current drops and the core, under the influence of gravity or a spring, falls, opening the circuit. These relays are position sensitive - they only operate in a certain orientation, which is usually indicated by an "UP" arrow on the housing.
Posistor relays (PTC) have no moving mechanical parts. They are based on a ceramic element (posistor), which, when heated by current, sharply increases its resistance, actually breaking the starting winding circuit. They are considered more reliable and less noisy, but they also fail, often losing their properties or cracking.
| Characteristics | Induction relay | Posistor relay (PTC) |
|---|---|---|
| Operation principle | Electromagnetic with a moving core | Thermal (resistance change) |
| Presence of moving parts | Yes (core, contacts) | No |
| Position sensitivity | High (strictly vertical) | Low (works in any position) |
| Characteristic sound | Loud click when starting/stopping | Silence or quiet crackling |
Is it possible to replace an induction relay with a posistor one?
Theoretically, this is possible, but it requires changing the electrical connection diagram and selecting the posistor resistance for a specific motor. A simple one-to-one replacement without redoing the wiring is most often impossible and can lead to combustion of the compressor.
Diagnostics of internal components and replacement
After you have succeeded remove the relay cover and remove the insides, you can carry out detailed diagnostics. In induction relays, the contacts often burn out or the core gets stuck. If carbon deposits are visible on the contacts, you can try to clean it with fine sandpaper or a file, but this is a temporary measure.
Checking the posistor is carried out with a multimeter in resistance measurement mode. In a cold state, its resistance should be in the range of 10-50 Ohms (the value depends on the model). If the device shows infinity or zero, the element is faulty and requires replacement. Also, the posistor should not have cracks or chips.
In most cases, repairing individual relay components is not economically feasible. The cost of a new starter protective device is usually low, and the reliability of the refurbished unit may be questionable. Therefore, experts recommend completely replacing the assembly.
- 🔍 Visually inspect the contacts for oxidation and carbon deposits.
- ⚡ Test the circuit with a multimeter to check the conductivity.
- 🔄 Compare the markings of the old and new relays before installation.
- 🧹 Clean the inside of the housing from dust and combustion products.
When installing a new relay, make sure that it sits tightly on the compressor terminals. Poor contact can cause arcing and further failure. If you change the type of relay (for example, from induction to universal), carefully study the connection diagram supplied with the new device.
⚠️ Attention: Never leave the relay disassembled when the refrigerator is plugged in. Exposed live contacts pose a lethal hazard. All assembly work must be completed before power is applied.
Assembling and checking the functionality of the system
The final stage is assembly of the unit. Reinstall the relay by sliding it onto the three pins of the compressor. Make sure it is seated all the way and locked. If the relay is inductive, check whether it is strictly vertical, according to the “UP” indicator.
Connect the wires to the contacts, focusing on the photographs taken earlier. The terminals must be put on with force and held tightly. If the terminal is loose, you can gently tighten it with pliers, but do not overdo it so as not to break the plastic. Check the reliability of all connections by lightly tugging the wires.
Now you can replace the compressor protective casing and secure it. Make sure that the wires are not caught under the screws or touching hot parts of the compressor or pipes. After installing the casing, turn on the refrigerator.
The first start after repair should take place without any extraneous sounds, except for the standard hum of the motor. Listen: if the clicking stops and the compressor runs smoothly, and after a while cold appears in the freezer, it means the repair was successful. During the first hour of operation, periodically check the temperature of the relay housing - it should not heat up above 50-60 degrees.
What to do if, after replacing the relay, the refrigerator does not start again?
If replacing the relay did not help, the problem may lie deeper. Perhaps the compressor itself is faulty (an interturn short circuit or wedge), the thermostat has failed, or the problem is in the control module (electronic board). It is also worth checking the integrity of the motor windings with a multimeter.
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the engine by applying voltage directly to the starting winding, but doing this is strictly not recommended without special skills. This can lead to burnout of the windings or a fire, since the thermal protection will not work. In addition, such a start will not ensure normal operation of the refrigerator.
How to choose an analogue if the original relay is not on sale?
When selecting an analogue, three parameters are important: engine power (indicated on the compressor nameplate), the type of relay (induction or posistor) and the location of the contacts. Universal relays often come complete with a set of adapters, which allows them to be used for various compressor models.
Why does the relay burn out repeatedly?
Frequent relay burnouts usually indicate problems with the compressor. If the engine is difficult to start due to wear or problems with freon, the starting currents increase and the relay cannot withstand the load. In this case, replacing the relay will only have a short-term effect.