The situation when the refrigerator ceases to make the usual hum, and the food begins to rapidly deteriorate, always takes you by surprise. Often the cause of a breakdown is the failure of the starting relay, which is responsible for starting the compressor engine. In emergency cases, when there is no original spare part on hand or urgent engine diagnostics are required, the question arises: is it possible to start the unit bypassing the standard circuit?
Direct connection of the compressor is emergency measureallowing you to temporarily restore the cold or check the serviceability of the engine itself. However, this method requires extreme caution, since working with high voltage electrical current and complex mechanical components carries risks. In this article, we will analyze the technical nuances, connection diagrams and critical safety points that must be taken into account when forcibly starting the motor.
Before taking any actions, it is important to understand that the standard operation scheme of the refrigerator is disrupted. Start-protective relay not only starts the motor, but also protects it from overheating and overloads. Ignoring this element can lead to the final failure of the equipment if time intervals and temperature control of the windings are not observed.
Modern models of refrigerators, especially inverter type, may have a completely different control architecture, where direct starting is impossible without a special controller. Therefore, the first step should always be to accurately identify the type of your compressor and assess the feasibility of intervention.
The principle of operation and the role of the starting relay
To understand what exactly we are excluding from the circuit, it is necessary to briefly consider the design of the single-phase asynchronous motor used in most household refrigerators. Such a motor has two windings: the main (working) and auxiliary (starting) windings. In normal mode, current flows to both windings, creating a rotating magnetic field necessary to start the rotor.
Starting relay performs the function of a circuit breaker. At the moment of switching on, it supplies voltage to the starting winding. As soon as the engine reaches the required speed, the current in the circuit drops or the magnetic field changes, and the relay opens the contacts, turning off the starting winding. Then the engine runs only on the main winding.
If the relay is faulty (the contacts are burnt, the mechanism is jammed), the starting winding circuit does not close, and the motor only hums, trying to move, or clicks, but does not start. It is at this moment that the need arises to simulate the operation of the relay manually.
⚠️ Attention: Operation without a relay deprives the engine of automatic protection. If you keep the starting winding on for too long, it will burn out in a matter of seconds due to overheating, since it is not designed for long-term operation.
There are two main types of relays that you can find: induction (current-driven) and posistor (thermal). The principles of their operation differ, but the goal is the same - a short-term impulse to start. When starting manually, we take over the function of this switch.
Tool preparation and fault diagnosis
Before starting any work, safety must be ensured. First of all, the refrigerator should disconnect powerby removing the plug from the socket. No manipulations with wires should be carried out under voltage. You will need a minimum set of tools: pliers, side cutters, insulating tape and, preferably, a multimeter to check the integrity of the windings.
Access to the compressor is usually located in the lower rear part of the unit. Having removed the protective casing, you will see a black metal cylinder - the compressor itself, to which a plastic box fits. This is the start relay along with a thermal fuse. Carefully remove the box, disconnecting the wires.
- 🔍 Visual inspection: Check the relay for traces of burning, melted plastic or the characteristic smell of burnt wiring.
- 🔊 Hearing test: Shake the relay near your ear. If a ringing or knocking sound is heard inside, it means that the internal contact group or posistor is damaged.
- ⚡ Checking with a multimeter: Ring the relay contacts. In a normal state, the resistance should be zero or close to it (for normally closed ones) or infinite, depending on the type.
It is also important to check the compressor itself for an interturn short circuit or open circuit. To do this, measure the resistance between the contacts on the motor block. Typically, the resistance between the common point and the working winding is about 10-20 Ohms, and between the common and starting windings - 30-40 Ohms. The total resistance between the starting and operating ones should be equal to the sum of these values.
If the measurements show infinity (break) or zero (short circuit) on the windings of the motor itself, then starting it without a relay is already useless - the motor is faulty. If the resistance is normal and the relay is “dead,” you can proceed to the direct start procedure.
Direct connection diagram of the compressor
The process of starting the engine without a standard relay consists of manually applying voltage to the starting winding at the moment the power is turned on. To do this, use a piece of wire with a plug or a button without locking. It is important to correctly determine the purpose of the contacts on the compressor block.
Usually the contacts are arranged in a triangle. The top contact is Common, the bottom left is the working winding (Run), the bottom right is the starting winding (Start). The exact markings can often be found on the relay body or in the technical documentation of the model Atlant, Indesit or Beko.
The algorithm of actions is as follows: power (220V) is connected to the common contact and the contact of the working winding. This creates a closed circuit, but the motor will not start because there is no starting pulse. At this moment, you need to briefly close the contact of the working winding with the contact of the starting winding.
| Contact on the block | Purpose | Wire color (standard) | Action when starting |
|---|---|---|---|
| Upper | Common (C) | Black / White | Connect phase |
| Left lower | Working (R) | Brown / Red | Connect zero |
| Bottom right | Start (S) | Blue / Green | Short circuit with R |
| Case | Grounding | Yellow-green | Do not touch during test |
As soon as you touch the starting contact, the motor should make a characteristic sound and start. After starting (literally after 1-2 seconds), the contact of the starting winding must be immediately broken. The engine will continue to operate on the working winding.
☑️ Checklist before starting
There is a method of using a regular button with normally open contacts. One wire from the network goes constantly to the working winding, and the second, going to the starting winding, is closed through a button. Press the button and the motor starts, release it and it works. This is a safer option than shorting with bare wires.
Organization of temporary operation and protection
Operation of the refrigerator in such an “emergency” mode is only possible for a short time. The main problem with not having a relay is the lack of thermal protection. If the pressure in the system increases (for example, due to a clogged capillary tube or a dirty capacitor), the current in the windings will increase and the motor will burn out, since the thermal release remains in the removed relay.
For more or less safe operation, it is necessary to organize external control. You can use a thermal relay from an old iron or washing machine by connecting it to the power circuit. It will break the circuit when the compressor housing is critically heated.
It is also important to consider the cyclical nature of work. Without standard automation, the refrigerator may not turn off on time, which will lead to food overfreezing or the evaporator freezing. You will have to manually monitor the temperature in the chambers and periodically disconnect the unit from the network.
⚠️ Attention: Never leave the compressor running without protection unattended for a long time, especially at night or when you leave home. The risk of a wiring fire or motor failure is extremely high.
Another nuance is the capacitor. In some circuits (especially old or powerful ones) there is a capacitor in parallel with the starting winding. When launching directly, it also needs to be taken into account. If it was in your circuit, it should be connected in parallel to the contacts that you close to start.
What will happen if you do not turn off the starting winding?
If you leave the starting winding energized for more than 2-3 seconds after the start, it will begin to overheat. The winding wire has a smaller cross-section and is not intended for continuous operation. The result is melting of the varnish, short circuit of the turns and expensive repairs or replacement of the compressor.
Typical errors and precautions
The most common mistake is incorrect identification of contacts. If you mix up the working and starting windings, the engine may start in the opposite direction (which is often fatal for a piston compressor) or simply hum and heat up without developing power.
The second mistake is using wires that are too thin for the “temporary”. The compressor starting current is 3-5 times higher than the rated current. A thin wire can melt in your hands at the moment of short circuit, which will lead to burns.
- 🚫 Ignoring phasing: Although for a single-phase motor phase and zero seem to be unimportant, in some circuits with capacitors this plays a role.
- 🚫 Long start: An attempt to hold the start button for more than 3 seconds, if the engine does not start. This is a sure sign of a malfunction of the mechanical part (jamming) or electrical.
- 🚫 Operation without grounding: When making a homemade connection, they often forget about the grounding circuit, which makes the refrigerator case potentially dangerous if the insulation breaks down.
It is also worth remembering about the refrigerant. If there is a freon leak in the system, the compressor will run idle, not cooling, but consuming current. In such conditions thermal protection is critically important, otherwise the motor will burn out very quickly.
Is it worth operating the refrigerator in this mode?
Starting the engine without a start relay is solely a diagnostic or temporary measure. You can’t count on long and reliable operation of the equipment in this condition. Lack of correct phasing of the starting winding (in terms of current or time) reduces the life of the engine.
Modern compressors, especially linear and inverter ones, cannot be started in this way at all. They require complex electronics that generate a sine wave of a specific frequency. Direct supply of 220V 50Hz to the windings of the inverter motor will lead to its instant failure.
If you successfully started the motor and the refrigerator began to freeze, this only means that the compressor is alive. But for full operation it is necessary to purchase and install a new starting relay. It is inexpensive and is sold in spare parts stores for household appliances.
The selection of an analogue is carried out according to the marking of the old relay or according to the engine power (indicated on the nameplate, for example, 1/5 HP, 1/4 HP). Universal relays often come complete with adapters, which simplifies installation on motors from different manufacturers.
Frequently asked questions (FAQ)
Is it possible to permanently leave the refrigerator operating without a relay if it freezes?
No, it is not possible. Without a relay, the starting winding will either not turn off (unless you open it), causing it to burn out, or the engine will start jerkily. In addition, you lose thermal protection, and if the pressure surges, the compressor will burn out without the possibility of recovery.
Why does the motor hum, but does not start even when the contacts are closed?
This may indicate several problems: jamming of the compressor piston group (mechanical failure), a break in the starting winding, or insufficient voltage in the network. It is also possible that you are closing the wrong contacts or holding them for too short a time.
Does the compressor burn out if you mix up the working and starting windings?
If you turn it on for a short time, most likely not, but the engine will not work correctly, heat up and hum. During prolonged operation in this mode, the starting winding, switched on as a working winding, will overheat and burn out, since it is not designed for direct current.
Where can I find the markings for selecting a new relay?
The markings are usually applied to the body of the old relay (for example, R600, PTM-11L). It is also important to look at the compressor power indicated on the sticker on the blackest cylinder (for example, 136 W or 1/4 HP). These parameters must match.
Is this dangerous for humans?
Yes, it is dangerous. You work with 220V mains voltage on open equipment, often in humid or cramped conditions. Careless movement may result in electric shock. Carry out all work only with the appliance unplugged, supplying power only during the test.