The situation when the refrigerator stops cooling, and only a quiet hum or complete silence is heard inside, often indicates a malfunction of the start relay. It is this small element that is responsible for supplying the starting pulse to the motor windings. Many amateur craftsmen are looking for a way to start a compressor from a refrigerator without a video relay to check whether the motor itself is alive before buying new spare parts or calling professionals.
Direct connection of the windings allows you to eliminate the possibility of breakdown compressor and focus on replacing the relay or other components of the system. However, this process requires strict adherence to safety precautions, as you will be working with high voltage and moving machinery under pressure. In this article, we will analyze the theoretical basis, connection diagram and visual aspects of the process, which are usually demonstrated in video instructions.
It is worth understanding that starting the motor directly is a temporary measure for diagnosis or an emergency, but not a permanent solution. A running engine makes a characteristic sound, and its shaft begins to rotate, creating the necessary pressure in the system. If the motor does not start even when directly connected to the network, the problem lies deeper, perhaps in an interturn short circuit or mechanical jamming of the piston group.
The principle of operation of the starting relay and the need to bypass it
The starting relay in the refrigerator performs the function of an automatic switch. At the moment of switching on, it supplies voltage to the starting winding, creating the torque necessary to start the rotor. As soon as the engine picks up speed, the current in the circuit changes, and the relay opens the contacts of the starting winding, leaving only the working winding. Without this device, the engine will only hum, but will not start, since a single-phase asynchronous motor lacks the initial impulse.
When we talk about starting without a standard relay, we actually take on the role of an automatic machine. We need to artificially apply current to the starting winding at the moment of switching on and remove it (or leave it, depending on the type of engine) immediately after start. In video instructions you can often see how craftsmen use a button or a special circuit to simulate this process. This allows you to check operability the compressor without waiting for delivery of a new part.
There are two main types of relays: posistor and inductive. PTCs work by heating an element, which changes its resistance, opening the circuit. Induction uses an electromagnetic coil. When connecting directly, it is important to understand what type you have, since the winding circuit may differ slightly, although the principle of supplying voltage to the starting and operating windings remains the same for most household models.
⚠️ Attention: When working with the electrical circuits of a refrigerator, there is always a risk of electric shock. Make sure you use proper tools, dry hands, and are on an insulating surface. Do not touch the wires while voltage is being applied.
It is important to note that prolonged operation of the compressor without a standard relay can lead to overheating of the starting winding, since it is not designed for direct current. Therefore, diagnostics should be carried out with short switching ons. If you see that the shaft begins to rotate and a steady hum is heard, it means that the electrical part of the engine is working properly.
Necessary tools and safety measures
Before you start manipulating the electrics, you need to prepare the workplace and tools. You don't need a complex professional kit, but a basic DIY kit is a must. The quality of the tools directly affects the safety and ease of work.
To complete the task you will need:
- 🔧 Screwdrivers (Phillips and flathead) for removing the casing and terminals.
- 🔌 Wires with clips (“crocodiles”) for temporary connection.
- 🔋 Power source (regular household socket 220V) with access to the switch.
- 🧤 Dielectric gloves for protection against accidental breakdown.
- 🔨 Hammer (light) for carefully knocking rust off the contacts, if necessary.
Pay special attention to the condition of the wires. The insulation must not be damaged and the contacts must not be oxidized. If you use a homemade push button to start, make sure it can handle the starting current, which can be several times higher than the rated current. Video lessons often show the use of a simple bell or starter button, but it is better to use specialized switching equipment.
Also prepare a multimeter. With its help, you can ring the windings for breaks or short circuits before connecting to the network. This is a critical step that beginners often ignore. Checking the resistance helps avoid a situation where you apply voltage to an already burnt-out motor, which can lead to knocked out plugs or damage to wiring in the house.
☑️ Check before starting
Do not forget that the compressor is fixed to the frame using shock absorbers. If handled carelessly, the copper tubes coming from the motor housing can be damaged. Any deformation or crack in the tubes will lead to freon leakage, which will turn a simple relay repair into an expensive refill of the refrigerator.
Diagnostics of the motor windings before connecting
Before applying voltage, you need to find three contacts on the compressor block. They are usually arranged in a triangle. On many modern models, such as Atlant or Indesit, the contacts are marked with the letters: S (Start), R (Run) and C (Common). However, on old Soviet refrigerators there may be no markings, and then you will have to search for contacts experimentally.
The process of searching for common contacts is as follows:
- 📏 Take a multimeter in resistance measurement mode (Ohm).
- 🔍 Ring all pairs of contacts with each other.
- 📝 Write down the values: the highest resistance will be between the starting and working windings (S-R).
- ⚡ The lowest resistance will be between the working winding and the common wire (R-C).
- 🔄 The average value will indicate the starting winding and the common wire (S-C).
The point that participates in the measurement with the lowest and average resistance is the common wire (C). It is to it and to the working winding (R) that the main voltage is supplied for operation, and to the starting winding (S) - only for starting. An error in identifying the contacts can lead to the engine humming, heating up, but not starting, or the thermal protection will work.
If the multimeter shows infinity (open) or zero (short circuit) between any contacts, starting such a compressor is useless and dangerous. In this case, the engine requires replacement or professional rewinding, which is practically impractical in domestic conditions. Video diagnostics often help to visually assess the condition of the contacts for carbon deposits.
After identifying the contacts, clean them with fine sandpaper if they are oxidized. Good contact is the key to a successful start and the absence of sparking, which can melt the plastic housing of the terminal block.
Connection diagram and step-by-step starting instructions
The most common and safest way to start a motor without a relay is to use a button with normally open contacts. The circuit is simple: one wire from the plug goes to the common contact (C), the second wire bifurcates. One branch goes directly to the working winding (R), and the second - through the button to the starting winding (S). By pressing the button, you simulate the operation of the starting relay.
Sequence of actions:
- Connect one end of the power cord to contact C (common).
- Connect the other end of the cord to contact R (working winding).
- Take an additional wire with a button. Press one end of the wire to contact S (starting), and the other to contact R (parallel to the main wire) or to the free end of the power plug (depending on the phasing, but it’s easier to parallelize it to R).
- Plug the plug into the socket. The engine will hum, but will not start.
- Press the button briefly, applying current to the starting winding. The engine should start.
- As soon as the motor picks up speed (after 1-2 seconds), the button must be released.
It is important not to keep the button pressed for too long. The starting winding is not designed for long-term operation under load. If the motor does not start on the first try, wait a few minutes for the thermal relay inside the compressor to cool down and repeat the procedure. In video instructions, this moment is often shown in close-up, focusing on the timing of pressing.
There is an alternative method using a capacitor, but it requires an accurate calculation of the capacitance corresponding to the engine power. For express diagnostics, the button method is the most universal and understandable for beginners. The main thing is to clearly feel the moment when the rotor breaks loose.
Analysis of the compressor operation and possible problems
After a successful start, it is necessary to evaluate the operation of the unit. A working compressor operates smoothly, without any extraneous knocking, clanging or metallic ringing. The vibration should be uniform. If you hear a loud knock of the pistons, this indicates mechanical wear or breakdown of the valve group.
Pay attention to the heating of the housing. In the first minutes of operation, the motor may heat up, but it should not heat up to temperatures at which it is impossible to hold your hand. Excessive heating may indicate an interturn short circuit of the windings or dry operation (without freon and oil), although short-term diagnostics usually do not lead to critical overheating.
Below is a table of possible symptoms and their causes during direct starting:
| Symptom | Probable cause | Actions |
|---|---|---|
| Humming, no start | No impulse is sent to the starting winding | Check the button and contacts |
| The machine knocks out | Short circuit in the windings | Stop trying, you need to replace the motor |
| Delayed start | Low voltage or worn bearings | Check the voltage in the network |
| Strong vibration | Damage to the internal suspension | Inspect the shock absorbers and fastenings |
If the compressor starts, but stalls after 10-20 seconds (a click is heard), which means that the internal thermal protection relay is activated. This may occur due to overheating or overcurrent. Under diagnostic conditions without a cooling system (condenser and evaporator), the motor may heat up faster, but if the protection is triggered in the first second, this is a bad sign.
⚠️ Attention: If smoke comes out of the compressor during startup or a burning smell appears, immediately turn off the power. It is prohibited to operate such a unit, as this can lead to a fire.
Frequent errors and nuances of the procedure
One of the most common errors is confusion in phasing or an attempt to supply 220V to the starting winding constantly. This is guaranteed to lead to the winding burning out. Also, beginners often forget that the refrigerator compressor is a closed system. If you bite into the copper tubes, gas will come out. You can start the compressor “into air” only for a short check (literally for a few seconds), since oil may begin to be ejected through open tubes, and engine cooling will be disrupted.
Another nuance is the condition of the oil. In older refrigerators, the oil could thicken or mix with moisture. When starting such a compressor without preheating (which is difficult to do without a standard circuit), the motor may jam. Video materials often show how craftsmen lightly tap the body during startup to loosen a jammed piston, but this is a “folk” method that does not always help.
Do not ignore the condition of the wiring in the refrigerator itself. Often it is not the relay that melts, but the block where it is inserted. If you start the motor through the button, but leave the burnt contacts in the connector, the problem will not go away when reassembling. Cleaning or replacing the terminals is a mandatory step.
Is it possible to leave the circuit with the button forever?
Theoretically it is possible, but it is not safe. The button may get stuck and the starting winding will burn out. In addition, the standard relay provides overload protection. Use the button only for diagnostics or as a temporary solution until the technician arrives.
Remember that modern inverter compressors (found in models LG, Samsung with the latest generation No Frost system) cannot be started in this way. They are controlled by an electronic unit and require alternating current of a certain frequency. The described technique is applicable only to classic asynchronous motors.
Final recommendations and conclusions
Starting a compressor without a relay is a useful skill for diagnostics, which allows you to save time waiting for spare parts. If the engine starts and runs smoothly, feel free to change the relay. If the engine is silent or hums, but does not spin even with the correct connection diagram, you will have to look for a new unit or contact a service center for complex repairs.
Always check the integrity of the wire insulation after work. Do not leave temporary twists or alligator clips in accessible places if you plan to reconnect the refrigerator to the network. Safety comes first, and not a single penny saved is worth the risk of life or fire in the apartment.
If you are not confident in your abilities or are afraid to work with high voltage, it is better not to take risks. Calling a specialist will cost more, but will guarantee safety and proper restoration of the functionality of your refrigerator. However, if you decide to act on your own, follow the instructions and pay attention to details.
Is it possible to start a compressor without a relay forever?
Technically, this is possible using a capacitor of a selected capacity, but it is not recommended. The standard relay provides protection and correct switching. Constant operation without it will shorten the life of the engine.
Why does the compressor hum but does not start?
Most often this indicates a malfunction of the starting relay or starting winding. Also, the cause may be jamming of the piston group or insufficient voltage in the network.
Is starting a compressor without freon dangerous?
A short start (for a few seconds) to check shaft rotation is safe. Long-term operation without freon will lead to overheating, since freon is involved in cooling the motor-compressor.
How to identify a burnt-out compressor?
If, when directly connected to the network (bypassing the relay), the motor does not make any sounds, does not hum or twitch, most likely there is a break in the windings. If the machine breaks, there is a short circuit.