The situation when the refrigerator suddenly stops freezing, and only a hum or complete silence is heard from the engine compartment, often confuses the owner. In most cases, the cause is the failure of the starting relay, which is responsible for supplying voltage to the starting winding of the engine. Starting the compressor without a relay It is necessary to carry out accurate diagnostics in order to understand whether the motor itself has burned out or the problem lies solely in the control circuit.
Direct connection of the windings to electrical network allows you to eliminate the malfunction of auxiliary elements and check the functionality asynchronous motor. However, it should be remembered that such an operation carries certain risks associated with high voltage and mechanical features of the piston group. In this article, we will analyze in detail the connection diagram, the necessary tools and precautions.
Before you begin manipulating electricity, you must clearly understand that you are dealing with a device operating under a voltage of 220 Volts. Carelessness can lead not only to the breakdown of an expensive unit, but also to injury. Safety should be the number one priority during the entire testing process.
The principle of operation of the trigger mechanism and the need to eliminate it
Standard A single-phase compressor used in domestic refrigerators is equipped with two windings: working (main) and starting. In order for the motor rotor to start rotating, it needs a phase-shifting pulse, which is precisely what the starting relay provides. In normal operation, the relay supplies current to the starting winding only at the moment of start, after which it turns it off.
When we talk about starting without a relay, we actually take on the function of this circuit breaker. This is required in situations where the relay has burned out, the contacts have stuck, or the circuit has broken, and the condition of the motor itself needs to be checked urgently. Direct connection allows you to apply voltage to both windings at once or artificially simulate the operation of the starting device.
⚠️ Attention: Long-term operation of the compressor with the starting winding connected (without turning off the relay) will lead to engine overheating and combustion. The test run should last no more than 3-5 seconds.
There are several types of relays: posistor and induction. The posistor ones work by heating the element, which changes the resistance, while the induction ones use an electromagnetic field to open the contacts. Understanding the type of device you have will help you correctly identify the contacts on the block.
What is the danger of starting without a relay?
If you leave the starting winding energized for too long, the current in it will increase to critical values. This will cause a thermal breakdown of the insulation and an interturn short circuit, after which the compressor will only have to be thrown away.
Necessary tools and safety measures
To carry out high-quality diagnostics, you will need a minimum set of tools that most home craftsmen can find. The main requirement is the insulation of all conductive parts to prevent accidental electric shock. Multimeter will become your main assistant for checking the integrity of the windings before applying voltage.
You will need the following items: screwdrivers for removing the casing, pliers with insulated handles, electrical tape and wires with alligator clips. It is also highly advisable to have on hand a working starting relay or a button for briefly closing the circuit if you plan to start the circuit more than once.
- 🔧 A set of screwdrivers for dismantling the compressor protective casing.
- ⚡ A multimeter to check the resistance of the windings and the absence of breakdown on the housing.
- 🔌 Wires with clamps for safe connection to contacts.
- 🧤 Dielectric gloves to protect hands when working under voltage.
Before starting any work, be sure to disconnect the refrigerator from the power supply. Even if you plan to immediately apply voltage for the test, initial diagnostics and preparation of contacts should be carried out on a completely de-energized device. Grounding The compressor housing is also an important safety factor.
Diagnostics of the compressor before direct connection
Before applying 220 Volts to the contacts, you need to make sure that the windings are intact and do not have a short circuit to the housing. To do this, use a multimeter in resistance measurement mode. First, check the resistance between the working and starting contacts, then between the working and common, and finally between the starting and common.
Normal resistance values usually vary between 10-30 Ohms for the starting winding and 15-50 Ohms for the working winding, depending on the power of the model. refrigeration unit. If the device shows infinity (break) or zero (short circuit), then there is no point in starting such a motor - it is faulty.
| Measurement type | Normal reading | Symptom malfunction |
|---|---|---|
| Working winding | 15 - 50 Ohm | Infinity or 0 Ohm |
| Starting winding | 10 - 30 Ohm | Infinity or 0 Ohm |
| Body breakdown | Infinity (∞) | Any resistance value |
Pay special attention to checking for insulation breakdown. One multimeter probe is applied to the cleaned area on the compressor housing (where there is no paint), and the second one to the contacts in turn. If the arrow of the device deviates or numbers appear on the screen, it means that the engine is hitting the housing, and its operation is fatal.
☑️ Check before starting
Winding connection diagram and contact identification
On the block The compressor usually has three main contacts, not counting ground. They may not be signed, so it is important to correctly determine which one is the general one, which one is the working one, and which one is the launcher one. In most modern models location diagram the following: at the bottom there is one contact (common), at the top there are two (working and starting).
To start the motor, you need to apply a phase to the working contact, and zero to the common one. However, to start, you need to briefly connect the starting contact with the working contact or apply voltage to it. Often, craftsmen use a bell button or simply carefully close the wires with insulated tool handles for a split second.
⚠️ Attention: Mixing up the working and starting contacts can lead to the humming of the motor without rotation of the rotor. If the compressor hums but does not start after 2 seconds, immediately turn off the power.
Sometimes the color coding of the wires helps in identification, but you cannot rely on it completely, since previous technicians may have made changes. The working winding always has greater resistance than the starting winding. By measuring the resistance between the three contacts, you will find the pair with the lowest resistance - these are the starting and operating windings, and the third remaining contact will be common.
The test run process and analysis of the results
After the contacts have been identified and the wires are prepared, you can begin the test. Connect one wire from the plug to the common contact, and run the second wire through the button or gap to the working contact. We do not touch the starting contact yet if we use the short-term circuit method.
Plug the plug into the outlet. If the motor hums but does not spin, briefly touch the starting contact with the wire. The engine should start and gain speed. If the startup is successful, the compressor will operate smoothly, without any extraneous knocks or vibrations. At this moment, it is important to monitor the temperature of the case.
When analyzing the work, pay attention to the following factors:
- 🔊 The sound of operation should be uniform, without metallic clanging.
- 🌡️ The case should not heat up above 50-60 degrees in a short time time.
- 💨 Air flow should be felt from the tubes (at suction and discharge).
If after starting the compressor works, but does not create enough pressure or consumes too much current, this may indicate mechanical wear of the piston group or loss of compression. In this case, replacing the relay will not solve the problem; the entire unit will need to be replaced.
Frequent errors and reasons for unsuccessful starting
Even with the correct connection diagram, beginners often make mistakes that lead to false conclusions about a compressor malfunction. One of the most common is insufficient holding time of the starting contact or, conversely, too long.
They also often forget about the capacitor, if it is provided for in the design of your model. Some circuits starting-protective device include a capacitor that helps to shift the phase. The absence of this element in the circuit can make starting impossible even with a working motor.
Consider typical failure scenarios:
- ❌ Humming without startup: Stucking of the piston group or lack of a starting impulse.
- ❌ Knocking out plugs: Short circuit in the windings or breakdown to the housing.
- ❌ Instant heating: Interturn short circuit requiring immediate shutdown.
⚠️ Attention: If the compressor does not start on the third try, further experiments may be useless and dangerous. Most likely, the motor has a mechanical defect or a hidden short circuit.
Do not ignore the condition of the wiring. Oxidized contacts or frayed wires can create additional resistance, which will not allow you to develop the required power to start. Always clean the contacts to a metallic shine before checking.
Why does the compressor start but immediately turn off?
This may be a sign of a faulty thermal protection relay. It is triggered by excess current or temperature, opening the circuit. Check the current consumption with an ammeter.
Final recommendations and further actions
If you managed to successfully start the compressor without a relay and it works stably, this is great news. This means that the expensive motor is working properly, and you only need to purchase a new starting relay, which costs much less. The selection of relays is carried out strictly according to the compressor model.
However, if you do not have sufficient skills in electrical engineering, it is better not to take risks. An incorrect connection can completely kill a still-living motor or lead to a fire. In such cases, it is wiser to contact a professional technician who will carry out diagnostics on a special stand.
Remember that temporary operation of a refrigerator with a “button” instead of a relay is impossible. The relay is needed to automatically turn off the starting winding. An engine left running will overheat and burn out in a matter of minutes. Therefore, after diagnostics, immediately install a new component.
Is it possible to leave the circuit with a button instead of a relay forever?
Absolutely not. The button is needed only for a short-term impulse. If you forget to turn it off or leave it on for too long, the starting winding will burn out. Automatic relays are vital here for long-term operation.
What current consumption is considered normal for a household compressor?
For most home refrigerators, the operating current is from 0.5 to 1.5 Amperes. At the moment of start-up, the current may briefly jump to 3-5 Amperes. Exceeding these values indicates problems with the mechanics or windings.
What to do if the contacts on the block are melted?
Fusing indicates poor contact and overheating. It is necessary to clean the contacts with a file or replace the block. If the melting has reached the compressor housing, the entire unit will need to be replaced, since the seal may have been broken.
Does the brand of the refrigerator affect the startup circuit?
The operating principle of asynchronous motors is the same for all brands (Indesit, LG, Samsung, Atlant). Only the location of the contacts on the block and the type of relay used (posistor or induction) may differ, but the logic for connecting the windings remains unchanged.