The situation when the refrigerator suddenly stops cooling, and the cause of the breakdown is the failure of the start-up relay, often takes the owner by surprise. At such moments, a natural question arises: is it possible to launch motor-compressor directly, bypassing the failed node? Such a need may arise to diagnose the performance of the engine itself or as a temporary measure until purchasing a new part.
However, it is worth immediately noting that standard the operating diagram of a household refrigerator requires the presence of a starting device. It provides acceleration of the rotor and protection of the windings from overheating. Direct connection electric motor to a 220 volt network is possible, but requires strict adherence to the sequence of actions and an understanding of the electrical processes occurring inside the sealed unit.
Before proceeding with any manipulations with electrical wiring, it is necessary to completely de-energize the unit. Unplug the power cord from the outlet. Any work inside the electrical part of the refrigeration cabinet is carried out only when there is no voltage in the network, in order to eliminate the risk of electric shock or short circuit.
The principle of operation of the starting relay and motor windings
To understand how to bypass the relay, you need to understand its function. A refrigerator compressor is an asynchronous motor with two main windings: working (main) and starting. In normal mode, starting relay applies voltage to the starting winding only at the moment of start, helping the rotor to spin up.
As soon as the engine reaches the required speed, the relay opens the starting winding circuit, and the motor continues to operate only on the working winding. If the starting winding is not turned off in time, it will burn out due to overheating, since it is not designed for long-term operation. That is why temporary connection requires manual control or the use of circuits.
Some older models used relays with a current coil, in modern ones posistor devices are more common. Posistor is a thermistor that heats up from the passing current and increases its resistance, opening the circuit. Understanding this principle is important for correct diagnosis.
⚠️ Attention: Long-term operation of the compressor with the starting winding turned on (without opening the circuit) will lead to thermal breakdown of the insulation and an interturn short circuit. The engine will fail irrevocably.
Necessary tools and safety measures
To carry out the starting procedure, you will need a minimum set of tools, which are found in most home craftsmen. It is important to prepare a workplace with good lighting in order to clearly see the color marking of the wires and the condition of the contacts.
The main tool is multimeter (tester). It is necessary not only to check the integrity of the windings, but also to determine their type (starting or operating) by measuring the resistance. It is absolutely impossible to work “at random” without this device.
- 🔧 Screwdrivers (phillips and flat) for removing the compressor casing.
- 🔌 Insulating tape or heat shrink for insulating connections.
- 🔦 Flashlight for illuminating hard-to-reach places in the compressor niche.
- 🧤 Dielectric gloves to protect hands when working under voltage.
You may also need a non-latching button (for example, from a doorbell) or a regular switch if you plan to conduct multiple tests. This will allow you to safely switch the starting winding circuit without touching the wires with your hands.
Diagnostics and determination of the type of windings
The first step after removing the protective casing and disconnecting the old relay is a visual inspection and continuity testing of the compressor leads. There is usually a diagram on the motor housing or on the relay itself, but often it is erased or unreadable. In this case, we rely on measurements.
Using a multimeter in resistance measurement mode (Ohms), alternately measure the resistance between each pair of three contacts. You need to find the pair with the lowest resistance - this will be the sum of the resistances of the working and starting windings, that is, the two extreme contacts.
The third contact, which is not involved in this pair with the lowest resistance, is Common (often labeled as C or COM). From the common contact to the other two, you need to measure the resistance:
| Pair of contacts | Resistance (Ohm) | Winding type |
|---|---|---|
| Common - Working | Smaller value (10-25 Ohm) | Working winding |
| Common - Starting | Larger value (30-50 Ohm) | Starting winding |
| Working - Starting | Sum of the two previous ones | Full circuit |
It is important to remember: the starting winding always has higher resistanceas it is wound with a thinner wire. The working winding has less resistance and thicker wire. An error in the definition will lead to the motor humming without starting or burning out.
Direct connection diagram via a button
The safest way to start a motor without a standard relay is to use a button without fixing. The essence of the method is to simulate the operation of a relay: you apply voltage to the starting winding only for the duration of the engine acceleration (1-3 seconds), and then release the button, opening the circuit.
Assemble the circuit as follows: one wire from the plug (phase) goes directly to the common contact of the compressor. The second wire (zero) goes to the working contact. But the starting contact is connected to the phase through a button. By pressing the button, you supply power to the starting winding.
☑️ Starting algorithm through the button
The process looks like this: you turn on the retail plug (the engine is stopped), briefly press the button. The engine begins to hum and accelerate. As soon as the sound of operation becomes smooth, the button must be released. If you release it too early, the motor will not start; if you release it too late, the starting winding will burn out.
⚠️ Attention: The time you hold the button should not exceed 2-3 seconds. If the motor does not start, try again no earlier than 5 minutes to allow the windings to cool down.
Connection via a capacitor (for powerful models)
In some cases, especially for high-power refrigerators or when using compressors from other systems, starting capacitormay be required. It creates the phase shift necessary to create torque and allows the engine to start more smoothly.
The capacitor is connected in parallel with the starting winding. Unlike the circuit with a button, here the capacitor can remain in the circuit (if it is working) or also be switched. For a one-time start, a circuit with a button is often used, but if the relay is burned out and the capacitor is intact, it can be used.
The capacitance of the capacitor is selected experimentally or according to the motor power correspondence table. Typically for household refrigerators these are values in the range from 2 to 5 µF at a voltage of at least 250V. Using a capacitor with a lower voltage will cause it to explode.
Is it possible to use a capacitor from a washing machine?
Yes, you can if its capacity and operating voltage are suitable. However, capacitors from washing machines often have a different design and may not be suitable in size or type of fastening. The main thing is to observe the polarity (if the capacitor is electrolytic, which is rare for starting) and voltage.
Checking performance and typical errors
After successfully starting the motor, it is necessary to evaluate its operation. The compressor should operate smoothly, without strong vibration and extraneous metallic knocks. The body temperature should increase gradually. A sudden heating of the lower part in the first minutes of operation is a sign of a malfunction.
A common mistake is to ignore the condition thermal relay, which is often built into the starting device or located nearby. If you connect the motor directly, you can bypass the thermal protection. This is dangerous: when the piston group jams, the motor will heat up until the insulation melts.
- ❌ Error: Connecting the starting winding directly to the network without opening. Result: smoke and burning smell after 10-15 seconds.
- ❌ Error: The working and starting contacts are mixed up. Result: the motor hums, but does not spin, it gets very hot.
- ❌ Error: Working without a capacitor on the motor, where it is required. Result: low starting torque, the engine cannot overcome the freon pressure.
If the engine starts, but stalls after a while (even with a button), perhaps the problem is not electrical, but mechanical: a jammed compressor or lack of refrigerant in the system. In this case, “dancing with a tambourine” at the electrical part will not help.
Temporary solution or complete replacement?
The use of the described starting methods without a relay should be considered solely as temporary measure for diagnostics or saving products before the arrival of a technician/purchase of a spare part. Constant operation of a refrigerator with manual switching or homemade circuits is unsafe.
Modern starting relays are inexpensive and are consumables. Replacing them takes 15 minutes and does not require special skills other than the ability to use a screwdriver. An attempt to leave the refrigerator forever without protection is fraught with a fire or failure of an expensive compressor.
Critical important: If you use the button method more than once, you must ensure that all connections are well insulated. Open twists of 220V wires near the metal body of the refrigerator create a deadly situation.In conclusion, although it is technically possible to start the motor without a relay, the safety and durability of the unit requires the installation of a standard or high-quality analog relay. Do not skimp on safety when it comes to complex household appliances.
What to do if the motor hums, but does not start even with the button?
Most likely, the problem is mechanical. The compressor could have seized due to exhaustion of the piston group or lack of oil. A break in the internal wiring or an interturn short circuit is also possible. Try (at your own peril and risk) to briefly apply voltage to the working winding, bypassing the starting winding, but this rarely helps with a wedge. Most often, such a compressor requires replacement.
Is it possible to use a relay from another refrigerator?
Yes, if the characteristics match. Pay attention to the markings (for example, RTP, R-1, LS-04.2B). It is important that the tripping current and type (positional, induction) match your motor. Universal relays often come complete with adapters for different types of legs.
Why does the starting winding burn out?
The starting winding has a thin wire and high resistance. It is intended only for a short-term current pulse at startup. If the relay is stuck and does not break the circuit, the current continues to flow through the thin winding, causing it to quickly overheat and melt the insulation in a matter of seconds.