A sudden stop of the compressor or a characteristic click, after which the refrigerator is silent, often indicate a problem in the engine starting system. Start relay - this is a small but critical unit that is responsible for supplying the starting impulse to the motor winding. If this element fails, the compressor hums, but does not start, or does not show signs of life at all, which leads to spoilage of products.
Independent replacement of this part is quite within the capabilities of a home craftsman with a minimum set of tools. In this article we will analyze in detail how to properly remove the starting relaycarry out its initial diagnosis and replace it with a new one without damaging other components of the unit. The correct approach to dismantling will avoid damage to tubes and electrical contacts.
Principle of operation and symptoms of malfunction
To understand the importance of the procedure, you need to know how the unit functions. Start relay connects the starting winding of the engine only at the moment start, and then turns it off when the engine reaches the required speed. In modern models, posistor devices are most often found, while in older units induction mechanisms with a coil and a moving core were used.
The breakdown can be determined by external signs. If you hear the motor trying to start, making a humming sound or clicking sound, and then after a few seconds there is a second click and silence - this is a sure sign that start relay is not doing its job. Also, a malfunction may be indicated by overheating of the compressor while the engine is running.
⚠️ Attention: If after clicking the compressor continues to hum for more than 10-15 seconds, immediately disconnect the refrigerator from the power supply. Prolonged operation in the “start” mode can lead to burnout of the motor windings.
Sometimes the cause is not the part itself, but oxidation of the contacts or mechanical jamming of the moving parts inside the housing. Before buying a new spare part, you should visually inspect the removed element for melting, cracks or a burning smell.
Preparation for work and safety measures
Any repair work with electrical appliances requires strict adherence to electrical safety rules. The first and most important step is to completely disconnect the refrigerator from the power supply. It is not enough just to turn off the button, you need to pull it plug from the socketto eliminate the risk of electric shock or short circuit.
To carry out the work you will need a minimum set of tools. A flat-head and Phillips-head screwdriver, as well as pliers, are usually sufficient. If you plan to check the continuity of the circuit, a multimeter will come in handy. Also prepare a clean rag to wipe the contacts from dust and possible moisture.
☑️ Preparation for repair
Ensure sufficient lighting of the working area. The compressor and relay are located at the bottom rear of the refrigerator, where dust and pet hair often get in. Carefully move the unit away from the wall to have free access to the motor from all sides.
Removing the compressor protective casing
The start relay is hidden under a protective plastic or metal casing that covers the back of the compressor. This casing protects electrical contacts from dust, moisture and mechanical damage. Depending on the model of the refrigerator, fastening can be done with latches or screws.
If the casing is secured with screws, carefully unscrew them, being careful not to drop the fasteners inside the unit. For models with plastic latches, lightly press the latches and remove the cover upwards or to the side. Be careful, as the plastic becomes brittle over time.
After removing the cover, you will have a view of the compressor, condenser and the starting unit itself. At this stage, it is important not to jerk the wires sharply and not to apply excessive force to the tubes coming from the motor. Copper tubes cooling systems are very thin-walled and are easily damaged.
The process of removing the start relay
The relay block itself is usually placed directly on the output contacts of the compressor and fixed in a metal frame or plastic holder. To remove it, you first need to disconnect the wires going to the contact group. They can be secured with terminals or simply pressed tightly onto the contacts.
Carefully remove the connector with the wires. If the terminals are oxidized and are tight, you can slightly rock them from side to side, but do not pull on the wire itself, so as not to break the wires. After turning off the power, you can begin to remove the relay housing itself from the motor contacts.
Take the relay by the housing and with a slight rocking movement, remove it from the three pins of the compressor. Remember or write down the orientation relay: it has a strictly defined “top-bottom” position, which is indicated by an arrow on the body. Installing the relay upside down will result in the impossibility of starting or breaking the new part.
Sometimes the relay is additionally secured in a metal bracket. In this case, you first need to unclench or unscrew the bracket, freeing the plastic case. Proceed carefully so as not to damage the contacts on the compressor itself.
Diagnostics and performance testing
After you have managed to remove the starting relay, it must be checked. A visual inspection often provides 50% of the information: the presence of carbon deposits, melted plastic or a burning smell indicates that the part requires replacement. If there are no external defects, you will need a multimeter.
To check a posistor relay (the most common type), you need to ring the contacts. In a cold state, the resistance should be within normal limits (usually several tens of ohms). If the device shows a break or infinity, the element is faulty.
For induction relays (with a coil and a moving core), the test consists of assessing the mechanical part. Turn the relay over: if a knocking sound is heard when shaking, this means that the movable core is loose or broken, which is a sign of a malfunction.
| Relay type | Test method | Normal result | Symptom breakdown |
|---|---|---|---|
| Posistor | Continuity test with a multimeter | There is resistance | Open circuit or short circuit |
| Induction | Visual + on hearing | The core does not loosen | Knock inside, jamming |
| Any | Visual inspection | The whole body, no burning | Fusing, cracks |
Installation of a new part and assembly
If diagnostics confirm a malfunction, a replacement is made. Install the new relay exactly in the same position in which the old one was removed. Focus on the marking UP or the arrow pointing up. Incorrect orientation will disrupt the mechanical or electrical operation of the unit.
Push the relay contacts onto the compressor pins until they stop. Make sure the connection is tight and the relay is not loose. If the design includes a fixing bracket, return it to its place and secure it. Then connect the connector with wires to the appropriate terminals.
Replace the compressor protective casing and secure it with screws or latches. Make sure the wires are not pinched or touching hot parts of the motor or pipes. After assembly, you can plug in the refrigerator and listen to the start-up character.
⚠️ Attention: If, after replacing the relay, the compressor hums but does not start, or immediately knocks out the machine in the panel, immediately turn off the power. Perhaps the problem is deeper (compressor jamming) or an installation error was made.
Common mistakes when replacing a relay
One of the most common mistakes is neglecting to clean the contacts. When installing a new part, it is recommended to clean the mating contacts on the compressor with fine sandpaper if they are oxidized. A dirty contact will lead to heating and rapid failure of even a new relay.
Another mistake is the use of force during installation. The plastic of older refrigerators is brittle and the contacts can be brittle. Excessive force can break the mounting ears or damage the terminals, which will create contact problems in the future.
Also, technicians often forget to check the condition of the wires going to the relay. Melted insulation or blackened wires indicate overheating, the cause of which must be eliminated. In this case, simply replacing the relay will not be enough - you need to restore the wiring.
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the motor without a starting device by giving a pulse manually, but this is dangerous and not recommended. Long-term operation without a relay will lead to the burnout of the compressor starting winding in a matter of minutes.
FAQ: Frequently Asked Questions
Is it possible to repair an old relay, or is it only necessary to replace it?
In most cases, repair is impractical. PTC elements cannot be restored, and in induction elements it is difficult to re-adjust the mechanics and contacts. The cost of a new part is low, so replacement is the only reliable solution.
Why does a new relay burn out immediately after installation?
This may indicate a malfunction of the compressor itself (turn-to-turn short circuit) or problems with the wiring. Also, the reason may be installing the relay in the wrong orientation or using a part with unsuitable characteristics for your motor model.
Where can I find the markings for selecting an analogue?
The marking is applied to the side face of the relay body. Look for the manufacturer's code (for example, Danfoss, RLT) or catalog number. You can also select according to the compressor model indicated on the sticker on the motor itself.
Is it dangerous to change the relay yourself?
If you follow electrical safety rules (disconnect from the network), the procedure is safe. The main risk is associated with the possibility of damaging the cooling system tubes due to careless movements in the limited space of the compressor niche.