Starting a refrigerator compressor without a relay: when is it necessary and how to do it correctly

Starting a refrigerator compressor without a relay is a necessary measure, which is resorted to in cases where the standard starting device has failed building, and it is temporarily impossible to replace it. This procedure requires an understanding of the operating principles of refrigeration equipment and strict adherence to safety precautions. It is important to realize that bypassing the relay is a temporary solutionand not a permanent alternative to repair. Without a properly functioning starting relay, the compressor runs the risk of overheating, getting damaged windings, or even burning out.

In this article, we will analyze in what situations it is justified to start the compressor bypassing the relay, what tools and knowledge will be required for this, and also describe in detail the step-by-step algorithm of actions. We will pay special attention to safety precautions - working with electricity if done incorrectly can lead to electric shock or fire. If you are not confident in your skills, it is better to entrust diagnostics and repairs to professionals.

Before you begin, make sure that the problem is in the relay, and not in the compressor itself or other elements of the circuit. To do this, you can check the resistance of the motor windings and the integrity of the contacts. In some cases, it is enough to clean the relay contacts or replace it with a new one - this is much safer than experiments with direct connection.

When may it be necessary to bypass the relay?

The refrigerator compressor relay performs two key functions: closes the power circuit when starting the motor and protects the windings from overheating. If it fails, the compressor either does not turn on at all or works intermittently. Bypassing the relay is relevant in the following cases:

• 🔧 Breakdown of the starting relay (melted contacts, mechanical damage to the case).
• 🔌 Lack of a replacement at hand when the refrigerator urgently needs to be started (for example, to preserve products).
• 🔍 Diagnostics of the compressor - checking whether it is able to work without the participation of a relay.
• ⚡ Emergency situations when other starting methods did not work.

However, it is important to understand that even a successfully started compressor without a relay will not be protected from voltage surges and overloads. This is fraught with:

• ⚡ Overheating of the windings and interturn short circuit.
• 🔥 Fire of insulation or contacts.
• 💥 Failure of other elements of the circuit (for example, a thermostat).

⚠️ Attention: If your refrigerator is still under warranty, any independent repair (including bypassing the relay) will invalidate it. Before intervening, check the service conditions.

Preparation: tools and safety measures

To start the compressor without a relay you will need:

• 🔧 Screwdrivers (phillips and flat) for dismantling the panel.
• 📊 Multimeter (to check winding resistance and voltage).
• 🔌 Insulated wires with terminals ("crocodiles") with a cross-section of at least 1.5 mm².
• 🛠️ Pliers and wire cutters for working with wires.
• 🧤 Dielectric gloves and shoes with rubber soles.
• 🔋 Power supply with voltage regulation (optional, for testing).

Before starting work required:

1. Disconnect the refrigerator from the network and discharge the capacitor (if it is is in the circuit).
2. Make sure that the floor around is dry and your hands are not wet.
3. Check the integrity of the insulation on all wires.
4. Prepare a fire extinguisher (in case of a short circuit).

⚠️ Attention: If the compressor previously worked intermittently (it rattled, sparked, emitted a burning smell), starting it without a relay could aggravate the breakdown. In such cases, it is better to first check the interturn resistance of the windings.

Compressor connection diagram without relay

A typical refrigerator compressor has three terminals:

• C (Common) — common contact.
• S (Start) — starting winding.
• R (Run) —working winding.

In normal mode, the relay briefly closes the circuit C-S to start, and then leaves only C-R for operation. When bypassing the relay, we need to manually simulate this process. Below is a simplified connection diagram:

Action algorithm:

1. Connect the phase (220V) to the contact C.
2. Connect zero (220V) to the contact R.
3. Connect for 1-3 seconds C i S (for example, a screwdriver with an insulated handle).
4. After starting the compressor, immediately disconnect C-S.

Critical: if you do not break the circuit C-S after starting, the starting winding will overheat and will burn out in a few seconds!

Disconnect the refrigerator from the network|Check the resistance of the windings with a multimeter|Prepare insulated wires|Wear dielectric gloves|Make sure there is no moisture on the contacts-->

Step-by-step instructions: how to start the compressor bypassing the relay

Let's consider the process on example of a typical compressor Embraco or Secop (common models in refrigerators Atlant, Indesit, Samsung). Before you begin, take a photo of the original connection of the wires to the relay!

Step 1. Removing the relay

Carefully remove the start relay from the compressor. It is usually secured with latches or screws. Disconnect the wires, remembering their location (it is better to mark them with electrical tape).

Step 2. Checking the windings

Use a multimeter in ohmmeter mode:

• Resistance between C-R: ~10-30 Ohm (working winding).
• Resistance between C-S: ~20-50 Ohm (start winding).
• Resistance between R-S: sum C-R and C-S (for example, 40-80 Ohms).

If the values are very different or tend to zero/infinity, the windings are damaged, startup is dangerous!

Step 3. Connecting the wires

Observe polarity:

• Phase wire (usually brown/black) - to C.
• Zero wire (blue) - to R.
• To S connect a temporary wire with a terminal.

Step 4. Startup compressor

Shortly (for 1-2 seconds) close C and S with an insulated tool. The compressor should start. If this does not happen:

• Check the voltage in the outlet (should be 220V ±10%).
• Make sure that the contacts are not oxidized.
• Try again, holding the short circuit for up to 3 seconds (no longer!).

Step 5. Monitoring operation

After starting:

• Listen to the compressor - it should operate smoothly, without knocking or vibration.
• Check the case temperature after 5-10 minutes (should not exceed 60-70°C).
• If the compressor turns off spontaneously, overheating or internal protection may be triggered.

⚠️ Attention: Do not leave the compressor operating without a relay for more than 1-2 hours. Long-term use without protection will lead to breakdown!

Common mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes when bypassing the relay. Here are the most common of them:

• ⏱️ Holding too long C-S: the starting winding is not designed for long-term operation. Maximum - 3 seconds!
• 🔌 Wrong polarity: If you mix up phase and zero, the compressor can rotate in the opposite direction (although most modern models are protected from this).
• 📉 Low voltage in the network: at a voltage lower A 190V compressor will not start or will operate with overload.
• 🔥 Ignoring the burning smell: if you feel burnt insulation during startup, immediately turn off the power!

How to minimize risks:

• Use voltage stabilizer to protect against surges.
• Do not start the compressor if it is hot to the touch (let it cool for 30-60 minutes).
• Check insulation integrity the wires before each connection.

If the compressor starts but immediately turns off, the following reasons are possible:

Alternative methods of starting the compressor

If bypassing the relay did not help or you do not risk working with high voltage, consider alternative methods:

• 🔄 Replacing the relay with a universal one: Spare parts stores sell universal starting relays (for example, Danfoss 103N0210 or Embraco EGX10H32), suitable for most compressors. Cost - from 500 to 1500 rubles.
• 🔋 Using a starting capacitor: In some models, the relay is combined with a capacitor. You can connect an external capacitor (for example, 25-40 uF) in parallel with the starting winding.
• 🔧 Repairing an old relay: Often the problem is melted contacts or a weakened spring. Carefully clean the contacts with sandpaper and check the mobility of the core.

For a temporary solution, a manual starter (a button with normally open contacts) is suitable, which can be installed instead of the relay. When pressed, it will close C-S, and after releasing it will leave only C-R.

How to choose a universal relay?

A universal relay is selected according to two parameters:

1. Operation current (indicated on the body of the old relay or in the compressor documentation). For example, for compressors with a power of 120-150 W, a 1.5-2.5 A relay is suitable.

2. Type of fastening (on latches or screws). Make sure that the new relay physically fits the connector on the compressor.

If it is not possible to find out the parameters, take a relay with an adjustable operating current (for example, Danfoss 103B1400).

When bypassing the relay is dangerous: signs of a critical malfunction

In some cases, starting compressor without a relay is not only risky, but strictly prohibited. Abandon the idea of bypassing if you observe:

• 🔥 A constant burning smell from the compressor - a sign of an interturn short circuit.
• 💥 Sparking or smoke when trying to start.
• 🔊 Knocking or grinding inside the motor - the piston or valves may break.
• 📉 The winding resistance is close to zero (short circuit).
• 🌡️ The compressor housing heats up to 80°C+ in a few minutes of operation.

In such cases, the only way out is replacement of the compressor. The cost of a new motor for a household refrigerator is from 3,000 to 10,000 rubles, in depending on the model. It is better to entrust the replacement to a specialist, since the system must be evacuated and refilled with freon.

If you still decide to take a risk, remember:

⚠️ Attention: A compressor with an interturn short circuit may explode upon startup! humming and smell of burnt insulation. Do not experiment with such equipment.

FAQ: Frequently asked questions about starting a compressor without a relay

Is it possible to constantly operate a refrigerator without a relay?

No, this is extremely dangerous. not only starts the compressor, but also protects it from overloads. Without it, the motor will quickly overheat, which will lead to failure of the windings or mechanical parts. The maximum operating time without a relay is 1-2 hours for emergency cooling of products.

How to understand that the relay has burned out and not the compressor?

Check. diagnostics:

1. Ring the compressor windings (resistance should be within 10-50 Ohms).
2. Check the relay: there should be no extraneous sounds when shaking (this is a sign of a damaged spring).
3. Inspect the relay contacts for melting or carbon deposits.

If the compressor windings are working properly, and the relay has visible damage, the problem is there.

What to do if the compressor hums, but does not start?

This is a typical sign:

• A jammed motor (mechanical blocking).
• Faulty starting capacitor (if it is in the circuit).
• The voltage in the network is too low.

Try:

1. Manually turning the compressor shaft (through a pulley, if any access).
2. Checking the capacitor with a multimeter (should show a capacity close to the nominal value).
3. Starting from a voltage stabilizer.

Which wire should be connected where if the markings are erased?

If it is not visible on the compressor designations C, S, R, identify the contacts by resistance:

• The lowest resistance is between C-R (working winding).
• Average - between C-S (starting winding).
• The highest is between R-S (the sum of the two windings).

The contact common to the two measurements with the lowest values is C.

Can I use a car relay to start?

Technically it is possible, but not advisable. Automotive relays are designed for other currents and voltages (usually 12V). For a household refrigerator (220V), only a specialized starting relay is suitable. In extreme cases, you can use contactor with normally open contacts, but this is a temporary solution.