The situation when the refrigerator suddenly stops cooling, and water begins to flow inside or food spoils, is familiar to many. At such moments, it is critically important to understand what exactly has failed: itself compressor or auxiliary elements, such as a start relay or thermostat. Often, craftsmen or experienced home craftsmen resort to the method of directly starting the engine to prevent damage to the very “heart” of the refrigeration system.
Starting the compressor, bypassing the standard automatic equipment, allows you to quickly diagnose the health of the motor. If, with a direct connection to the network, the engine starts confidently and runs smoothly, then the problem lies in the control circuit. However, this method requires strict adherence to safety precautions, since you are working with high voltage and bare wires.
In this article we will look in detail at how to safely carry out diagnostics, what tools will be required and what to pay special attention to when checking. start-protective relay. Remember that any work on electrical equipment should be carried out only when the power is turned off, and the test run itself should be short-term and under constant supervision.
Fault diagnosis before direct start
Before grabbing wires and screwdrivers, you need to make sure that the problem really lies without starting the compressor. Often, users mistakenly believe that the motor has broken down, although in fact it could have burned out thermostat or the wiring has broken. Primary visual inspection and listening to the operation of the unit can provide up to 50% of information about the nature of the breakdown.
If, when you turn on the refrigerator into the network, you hear a quiet click, followed by a hum that lasts a few seconds, and then another click and silence - this is a classic symptom of a faulty starter or jamming piston group. In this case, direct starting will help to understand whether the motor is capable of rotating at all.
⚠️ Attention: If the compressor makes a loud metallic knock or a burning smell when trying to start, immediately stop any manipulations. This may indicate an interturn short circuit or mechanical destruction of the nodes.
To carry out an accurate diagnosis, you will need a minimum set of tools. You should not try to twist the wires without insulation, as this can lead to a short circuit and electric shock.
- 🛠️ A set of screwdrivers for removing the back cover and dismantling the compressor casing.
- ⚡ A multimeter or tester for checking the integrity of the windings.
- 🔌 Wires with crocodile clips for safe connection.
- 🧤 Dielectric gloves to protect hands.
It is also important to check the condition of the power cord and socket. Sometimes a banal lack of contact in a plug or oxidation of contacts in a connector simulates the breakdown of a complex unit. Make sure that the voltage in the network is stable and corresponds 220-230 V.
The design of the starting relay and the principle of its operation
To understand how to start a refrigerator without a relay, you need to at least superficially understand why it is needed. Starting relay is an automatic switch that supplies current to the starting winding of the engine only at the moment of start. As soon as the rotor reaches the required speed, the relay opens the starting winding circuit, and the engine continues to operate only on the working winding.
In modern refrigerators, posistor-type or induction relays are most often found. Posistor models work due to the property of the material to heat up and lose conductivity, opening the circuit. Induction rely on the magnetic field created by the current in the working winding, which draws in the core and closes the contacts of the starting circuit.
In parallel with the starting function, in many models the relay is combined with thermal protective relay. It opens the compressor power circuit if the current consumption exceeds the norm or if the motor housing heats up above a critical temperature. This prevents the windings from burning out when the pistons jam.
Why do relays burn out?
A frequent cause of relay failure is voltage surges in the network or natural wear of the contacts. Also, the relay can burn out if the compressor is overloaded due to contamination of the condenser at the back of the refrigerator.
During direct start, we artificially simulate the operation of a working starting relay, applying voltage to the right contacts at the right time. Understanding the winding diagram is key here.
Compressor winding connection diagram
Domestic refrigerator compressors, as a rule, have three terminals on the terminal block. These pins correspond to the ends of the windings: starting, working and general contact. Incorrect identification of these contacts can lead to instant combustion of the engine or electric shock.
The location of the contacts on the block is usually standardized, but it is better to double-check them with a multimeter. If you look at the block from below (with the contacts facing you), the triangle of contacts often has the following configuration: the upper corner is the common wire, the lower left is the working winding, the lower right is the starting winding.
| Contact | Designation | Resistance (Ohm) | Purpose |
|---|---|---|---|
| Common | C / General | Minimum (amount) | Power (Phase/Zero) |
| Run | R / Working | Average value | Main work |
| Start | S / Start | Maximum value | Engine start |
| Case | Ground | Infinity | Grounding |
To check the resistance, remove the relay and connect the multimeter probes to the pairs of contacts. Between the working and starting windings, the resistance should be the sum of the resistances of each winding relative to the common wire. Between any contact and the copper tube of the compressor (housing), the resistance should be infinite.
If the multimeter shows zero between the contact and the housing, it means that something has happened. breakdown to the housing. It is strictly forbidden to operate such a compressor, as it is deadly. Direct starting in this case does not make sense.
Instructions: how to start the compressor directly
The most critical stage is direct connection. To do this you will need a piece of wire with a plug. One end of the wire (phase) will be connected to the common contact, and the second end (zero) to the contact of the working winding. The starting winding must be briefly short-circuited with the working winding or voltage must be applied to it only at the moment of start.
There is a simplified starting method using a button or a short-term connection of wires. Be extremely careful: when connecting the contacts, it may slip electric arc. Carry out all manipulations in dielectric gloves and dry shoes.
☑️ Safe start of the compressor
The action algorithm is as follows: connect one wire from the plug to the common contact, and split the second wire. Connect one end of the second wire permanently to the working winding, and touch the starting contact with the free end of the same wire. As soon as the engine starts (after 1-2 seconds), the starting contact must be released.
If the engine starts and picks up speed, release the starting circuit. The motor should continue to run smoothly, without humming or vibration. If, after releasing the start button, the motor stops or hums, then the problem is in the mechanical part or windings.
It is important not to keep the starting winding energized for more than 3-5 seconds. This can lead to overheating and burning of the starting winding, since it is not designed for long-term operation. Thermal relay in this case it will not work, since we excluded it from the circuit.
Analysis of results and troubleshooting
After a successful or unsuccessful start, it is necessary to analyze the behavior of the compressor. The nature of the engine’s operation will tell you more about its technical condition than any external signs. If the startup was successful, but the refrigerator still does not cool, the problem may be a leak refrigerant or a clogged capillary tube.
If the motor hums, but does not start even with a starting impulse, the piston group may be jammed. In some cases, the “pinging” method helps (applying increased voltage), but it is not recommended to do this at home due to the risk of completely killing the compressor.
Pay attention to the temperature of the case. If the compressor starts, but after a minute of operation the housing becomes hot, and the current consumption is higher than the rated one, this is a sign of an interturn short circuit in the windings or problems with the lubrication system.
⚠️ Attention: The normal current consumption of a household compressor is 0.5 - 1.2 Amperes. If the ammeter shows 3-5 A or higher, the engine is faulty and requires replacement.
It is also worth checking the condition of the oil. If, when connecting a pressure gauge or opening the system, it turns out that the oil is black and has a burning smell, the compressor was overheating. In this case, even a successful start without a relay does not guarantee a long life for the unit.
For more accurate diagnostics, you can use the table of typical faults:
- 🔊 Humming and clicking - the starting relay is faulty or jammed.
- 🔥 Heating of the housing during operation - interturn short circuit or lack of freon.
- 💨 Quiet operation without cold - freon leakage or blockage.
- ⚡ Knocking out plugs - breakdown on the body or short circuit.
Safety measures and common errors
Operation There is always a risk with 220V electrical appliances. The most common mistake is neglecting to insulate hands and tools. Accidentally touching a bare wire with one hand and the grounded body of the refrigerator with the other can lead to electrical injury.
Another common mistake is long-term operation of the compressor without a relay and without a cooling system. When starting directly in a workshop, the compressor is often not connected to the piping system. In this mode, it can only work for a few minutes, otherwise overheating of the cylinder head is inevitable.
Do not forget that there may remain residual pressurein the system. Before any work with the pipes (if you decide to check the pressure), make sure that the refrigerant is released in accordance with environmental standards, although this is not required for a simple electrical test.
If you are not confident in your abilities or do not have experience working with electrical circuits, it is better not to take risks. Repairing a refrigerator can be dangerous, and incorrect diagnosis will lead to unnecessary expenses for purchasing a new compressor.
Is it possible to leave the refrigerator working without a relay all the time?
Absolutely not. Without a start relay, the compressor will not be able to restart on its own after being stopped by the thermostat. In addition, the lack of thermal protection will lead to the windings burning out at the first overload or power surge.
What to do if the compressor starts, but the machine immediately knocks out?
This is a sign of a short circuit in the windings or a breakdown on the housing. It is also possible that the start winding is not turning off and is creating too much current. The compressor needs to be replaced.
How to determine whether the compressor or just the relay has burned out?
You need to test the windings with a multimeter. If the resistance between the contacts and the body is infinite, and there are specific values between the contacts (not zero or infinity), then the windings are intact. This means the problem is in the relay or wiring.
Is it dangerous to touch the compressor during operation?
Yes, it is dangerous. Firstly, you can get an electric shock if the insulation is broken. Secondly, the temperature of the discharge tube and cylinder head can reach 90-100°C, which will lead to burns.
Is it necessary to change the oil in the compressor when replacing the relay?
No, when replacing only the electrical part (relay), there is no need to change the oil or open the system. The oil is changed only when replacing the compressor itself or major repairs to the system.