The situation when the refrigerator stops cooling and the engine is silent often confronts the owner with a difficult choice: call a technician or try to figure it out on his own. One of the common causes of breakdown is the failure of the starting relay, which is responsible for supplying voltage to the electric motor windings. In some cases, especially when it is necessary to urgently freeze food or check the serviceability of the motor itself, the question arises: is it possible to start the refrigerator compressor without a relay. The answer is yes, but this process requires strict adherence to safety precautions and an understanding of the principles of operation of electrical equipment.
Direct connection using workarounds allows you to temporarily revive the unit or diagnose more serious faults, such as an interturn short circuit or jamming of the piston group. However, you should understand that working without standard protection is a risk. Start relay it doesn’t just start the motor, it protects it from overloads and overheating. Ignoring this element in the long term can lead to the final burnout of the windings, so this method should be considered solely as a temporary measure or diagnostic test.
Before you begin manipulating electricity, you must make sure that there is no voltage in the network. Any work with 220 volt wiring poses a real threat to life. In addition, refrigerant circulates in the system, and careless handling of the tubes can lead to damage. If you are not confident in your abilities or do not have basic skills in working with a multimeter, it is better not to take risks and entrust the repair to professionals. But if the decision has been made, then we will next consider the technical aspects of this process.
⚠️ Attention: Direct connection of a compressor without automatic protection creates a risk of electric shock and fire. Never leave a device plugged in unattended, even for a minute.
The principle of operation of the starting relay and the need to replace it
To understand how to start a refrigerator compressor without a relay, you must first understand why it is needed at all. The starting device is an electromagnetic or thermal switch that briefly supplies voltage to the motor's starting winding. At the moment of switching on, the motor consumes a huge current, and it is the starting winding that creates the necessary magnetic torque to rotate the rotor. As soon as the engine picks up speed, the relay opens the starting winding circuit, and the motor continues to operate on the main one.
If this element is faulty, the starting winding circuit does not close, and the engine only hums, but does not start. Some models use positor, which changes its resistance when heated, opening the circuit. In older models, there are relays with a moving core. The absence of a relay at startup means that you will have to manually simulate its operation: apply voltage to the starting winding only at the moment start, and then turn it off. If this is not done, the starting winding will burn out in a matter of seconds due to overheating.
There are several types of relays, and their design affects the bypass pattern. For example, in devices RT or R-1 contacts open under the influence of gravity when the current drops. Understanding these mechanics helps you manually reproduce the process. However, it is worth noting that modern inverter compressors are controlled by complex electronics, and the “collective farm” starting method is incompatible with them. We are considering classic asynchronous motors that are found in most old refrigerators Atlant, Biryusa or Indesit.
In addition, The thermal relay protects the motor from overcurrent. If the compressor seizes or the current increases due to a voltage surge, the bimetallic strip inside the relay will open the circuit, saving the windings. By starting the engine directly, you deprive yourself of this protection. Therefore, monitoring the temperature of the motor housing and the current becomes your direct responsibility during the testing process.
Necessary tools and precautions
Preparation of the workplace is the key to success and safety. You will need a minimum set of tools that any home craftsman will have. The main thing is not to use damaged wires or tools with damaged insulation. Before starting work, be sure to disconnect the refrigerator from the power supply by removing the plug from the outlet. Even if you plan to apply voltage, you need to do this only at the final stage of testing.
To carry out diagnostics and start-up you will need:
- 🛠️ Multimeter — to check the integrity of the windings and the presence of voltage.
- 🔌 A piece of wire with a plug for connecting to the network.
- 🔧 Screwdrivers (flat and cross) - for removing the casing and terminal box.
- 🧤 Dielectric gloves - for protection against accidental electric shock.
- 🔦 Flashlight —for illuminating hard-to-reach places in the engine compartment.
Pay special attention to the condition of the wires. The insulation must be intact, without cracks or melting. If you are using a homemade wiring diagram, all connections must be securely twisted and, preferably, soldered or insulated with heat shrink. The “twisted” contact can spark, which is extremely undesirable near refrigerant (which theoretically can be flammable in certain concentrations, although freon is usually inert) and plastic.
It is also important to ensure good ventilation in the room. The compressor gets hot when running, and if you run long tests, the temperature in the engine compartment can rise significantly. Do not cover the refrigerator with rags or block air access to the condenser during experiments.
⚠️ Attention: Freon used in refrigerators can form toxic compounds when in contact with an open flame. It is strictly forbidden to smoke or use open fire near a running compressor.
Diagnostics of the compressor before starting
Before trying to start the engine directly, you need to make sure that the problem is in the relay, and that the compressor itself is working. An attempt to start a jammed motor or a motor with an interturn short circuit can lead to knocked out plugs or fire of the wiring. The first step should always be a visual inspection and "continuity" of the windings.
Remove the back cover of the refrigerator and get to the compressor. Disconnect the wires from the start relay. The motor terminal block usually has three terminals arranged in a triangle. Two of them are the ends of the working and starting windings, and the third is common. The resistance between them is measured with a multimeter in ohmmeter mode. Normal resistance values vary depending on the power of the motor, but are typically 10 to 30 ohms for the run winding and 30 to 50 ohms for the start winding.
Check the resistance between each terminal and the compressor housing (metal part). The device should show infinity. If the multimeter shows at least some resistance or beeps, it means that something has happened breakdown to the housing. Such a compressor cannot be used - it is mortally dangerous. Also check the integrity of the windings themselves: if the resistance is infinitely high, it means that the winding is broken and the motor is inoperative.
☑️ Diagnostics before starting
If everything the parameters are normal, you can proceed to determining the conclusions. On some models they are marked with letters: S (Start) - starting, R (Run) - working, C (Common) - general. If there are no markings, you will have to calculate them empirically: the resistance between the working and common windings is always less than between the starting and common windings.
Diagram of direct connection of windings
The most common way to start a refrigerator compressor without a relay is to manually apply voltage to the starting winding. For this, a temporary chain is assembled. You will need a wire with a plug that will be connected to the common and working windings permanently, and a separate piece of wire for short-circuiting the starting winding.
The algorithm of actions is as follows:
- One end of the network wire is connected to the common terminal (
C). - The other end network wire is connected to the working terminal (
R). - The third wire (jumper) is connected at one end to the starting terminal (
S), and do not connect the other end anywhere yet. - Plug the plug into the socket. The motor will hum, but will not start.
- With the free end of the jumper, touch the terminal to which the zero is applied (usually this is the same terminal where the second end of the network wire is connected, or directly to the working winding, depending on the 220V circuit).
At the moment of touching, the engine should start. As soon as you hear the motor running confidently, the jumper must be immediately removed. The starting winding should no longer be removed. is needed, it has fulfilled its function. Then the compressor will work on the working winding. It is important not to overexpose the jumper: 1-2 seconds is enough. If you hold it longer, the starting winding will start to heat up and may burn out.
Why can’t you hold the jumper for a long time?
The starting winding is wound with a thinner wire and has a higher resistance. It is not intended for long-term operation under load. When connected for a long time, the current in it causes rapid heating, destruction of the varnish insulation and a short circuit of the turns. This will lead to irreversible damage to the compressor.
There is also a circuit using a button. Instead of holding the wire with your hand (which is dangerous and inconvenient), you can use a button without locking (for example, from a doorbell). windings. Pressed - the motor started, released - the starting winding circuit was broken. This is a safer and more professional approach to diagnostics.
Using a capacitor to start
A softer and more effective way to start, especially for powerful or old compressors, is to use a starting capacitor. the necessary phase shift for the torque to occur. The capacitor is connected in parallel to the starting winding.
The capacitance of the capacitor is selected experimentally or according to tables, usually it is from 4 to 10 μF for household refrigerators. The capacitor voltage should be at least 400-450 Volts. The connection diagram is similar to the previous one, but between the starting terminal and the wire. going to the network, the capacitor is turned on. This avoids sudden surges of current and reduces the load on the contacts.
Advantages of using a capacitor:
- 💡 Smoother engine start, less vibration.
- ⚡ Reduced starting current, which saves wiring.
- 🔄 Possibility of starting "tired" motors that do not start directly.
However, even with a capacitor, the starting winding circuit must be opened after starting, unless you use a special circuit with a thermal relay. Otherwise, the capacitor may swell or burst from overheating, and the winding will burn out. For continuous operation without a standard relay, this circuit may swell. cannot be used, only for testing or a temporary solution.
Table of typical resistances windings
For correct diagnosis, it is important to know the approximate resistance values. They depend on the engine power and manufacturer. Below is a reference table for the most common compressor models.
| Compressor model | Operating winding resistance (Ohm) | Starting winding resistance (Ohm) | Total resistance (Ohm) |
|---|---|---|---|
| Atlant 10LK | 25.0 | 40.0 | 65.0 |
| Danfoss NL11F | 22.5 | 35.0 | 57.5 |
| Secop SC12CL | 18.0 | 32.0 | 50.0 |
| LG MA110YC | 14.5 | 28.0 | 42.5 |
Remember that the values may differ slightly depending on the engine temperature. A “cold” engine has less resistance than a “hot” one. the measurements are radically different from the tabular ones (for example, half as much), this is a sure sign of an interturn short circuit. Such a motor will not last long and will get very hot.
⚠️ Attention: Technical characteristics of compressors may vary depending on the year of manufacture and the specific modification. Always check the technical documentation (datasheet) for the specific engine model, if available.
Frequent errors and possible consequences
When trying to repair things on their own, beginners often make mistakes that can cost equipment. One of the most common is confusion in the voltage. 220V to the starting winding instead of the working one (or vice versa, depending on the circuit) will lead to instantaneous combustion of the winding. Always double-check the connection diagram three times before turning it on.
Another mistake is ignoring heating. When starting the motor without a relay, you must constantly monitor the temperature of the housing with your hand. If after 5-10 minutes of operation the housing cannot be held by hand, then there is an overload or a problem with the cooling system of the compressor itself. (for example, the capillary is clogged or the fan, if any, is faulty). Long-term operation in this mode will lead to thermal destruction of the insulation.
It is also dangerous to leave such a “temporary” circuit on a permanent basis. The absence of thermal protection means that if there is a voltage surge in the network or the piston is jammed, the motor will burn out instead of simply turning off. In addition, sparking at the point of manual contact can cause it. fire.
If after starting the compressor works, but does not cool, the problem may not be in the electrics, but in the mechanics or refrigerant. Possible:
- 🧊 Freon leak — the motor is running, but there is no cold.
- 🔨 Clogged capillary tube — the sound of pouring water or hissing is heard.
- ❄️ Thermostat malfunction —the compressor does not receive a command to turn on from the control board.
Is it possible to drive with a directly sealed compressor until the arrival of a specialist?
Theoretically, it is possible if you constantly monitor the process. But in practice, this is a “time bomb.” It is better to wait for a specialist or replace the relay, the cost of which is not comparable with the risk of losing the entire refrigerator.
FAQ: Frequently asked questions
How long can you keep the compressor on without relay?
Only for the time necessary for diagnostics (5-15 minutes). Long-term operation without thermal protection is prohibited, as this can lead to a fire or permanent breakdown of the motor if overloaded.
Why does the compressor hum, but does not start even with a jumper?
Most likely, the piston group is jammed due to oil production or mechanical damage. A strong breakdown of the winding insulation is also possible. In rare cases, "swinging" with current helps, but most often the unit needs to be replaced.
Is it possible to use a regular automotive relay for replacement?
No. refrigerators reach tens of amperes, and a regular car relay will instantly burn out or stick. You need specialized starting relays designed for inductive loads and high currents.
Is it dangerous to touch the compressor housing during operation?
Yes, if the insulation is broken or there is a breakdown in the housing, you can get an electric shock. In addition, the housing gets very hot. (up to 70-90 degrees), which can cause a burn. Carry out all manipulations only with the power off.
Where can you find the winding resistance markings?
Usually it is not written explicitly in Ohms. You need to look at the compressor model on the nameplate and search for technical documentation (datasheet) on the Internet using the query “model + resistance” or use reference books. tables of masters.