How to connect a refrigerator compressor directly without a relay: diagram, risks and nuances

Connecting the refrigerator compressor bypass starting relay is a necessary measure, which is resorted to when a standard module breaks down or in the absence of a replacement. However, this method is fraught overheating of the windings, reducing the service life of the unit and even fire hazard. Before taking up the soldering iron, it is important to assess the feasibility: in 80% of cases it is cheaper and safer to replace the relay than to risk an expensive compressor.

This article is detailed will analyze direct connection diagrams for different types of compressors (Lunard, Secop, Embraco), explain why you cannot ignore thermal protection, and warn against common mistakes. If you are not confident in your skills in working with electricity, it is better to contact a specialist. But if your determination is inexhaustible, let’s get down to theory and practice.

1. When is it permissible to connect a compressor without a relay?

Direct connection of a compressor is temporary solutionand not a permanent measure. It is used in three cases:

• 🔧 Fault diagnosis: to check whether the compressor is working when there is a break in the relay circuit.
• ⚡ Emergency cooling: when you urgently need to save food, and the relay is burned out (for example, in refrigerators Stinol 102 or Biryusa 18).
• 🛠️ Lack of spare parts: if the original relay for a rare model (for example, Zanussi ZRA 33) cannot be found quickly.

Even in these cases operating time without a relay should not exceed 2–3 hours in a row. Longer - and the risk of overheating of the windings increases significantly. Why? Because the starting relay not only starts the motor, but also disables the starting winding after acceleration, preventing its combustion.

⚠️ Attention: In refrigerators with inverter compressors (for example, LG Door-in-Door or Samsung RB37) direct connection prohibited. Their electronic control boards are incompatible with manual bypass of the relay - this will lead to an instant error or failure.

If your refrigerator is older than 10 years (for example, Minsk 128 or Nord 243), the chances of successful connection are higher - their compressors are less sensitive to overloads. Modern models (Beko CN 325220, Liebherr CP 3023) are often equipped with additional electronics that can block starting without a relay.

2. The structure of the compressor and the role of the relay: what do we bypass?

To understand how to connect the compressor directly, you need to understand its “anatomy”. Any refrigerator compressor has:

• 🔌 Working winding (R) —the main one, it works constantly.
• 🚀 Starting winding (S) - turns on only for 1-2 seconds to accelerate the rotor.
• 🛡️ Thermal relay (built-in or external) - protects against overheating.

The starting relay performs two functions:

1. It closes the starting winding circuit at the moment of switching on.
2. It opens it after the motor accelerates (after 0.5–1.5 seconds).

Without a relay, the starting winding will remain energized constant, which will lead to its overheating and interturn short circuit.

In posistor relays (aka PTR relays) the starting winding is turned off due to the heating of the posistor. If connected directly, it will have to be turned off manually after 1-2 seconds, otherwise it will burn out. In current relays (for example, RTK-1) the winding is switched off by current, and it can be left connected longer - but no more than 5-10 seconds!

What is an interturn short circuit?

This is a short circuit between the turns of one winding, which occurs due to overheating. Signs: the compressor hums, but does not start, it gets very hot. case, the protection is triggered. In 90% of cases, the compressor needs to be replaced.

3. Compressor connection diagrams without a relay

There is a direct connection, but they all require an understanding of electrics. If you do not know how to use a multimeter, it is better not to risk it. data-i="138">three working diagrams three working schemes direct connections, but they all require an understanding of electrical wiring. If you don’t know how to use a multimeter, it’s better not to risk it.

Scheme 1: For current relays (RTK, DHR)

Suitable for old refrigerators (ZIL, Saratov, MinskProcedure:

1. Disconnect the relay from the compressor.
2. Find contacts:
   • C (general)
   • R (working winding)
   • S (starting winding)

Connect C → R directly to the 220V network.

Connect briefly (for 1-2 seconds) startup. S → C to start.

Scheme 2: For posistor relays (RTP)

Relevant for Atlant, Indesit, Ardo. Here you need to simulate the operation of a posistor:

1. Unsolder the relay from the compressor.
2. Connect C → R to the network.
3. Connect a resistor in parallel to the working winding 10–20 kOhm (for 1–2 seconds) to start.

Scheme 3: Through a button (temporary option)

The safest method for non-professionals:

• 🔘 Use a button without fixation (for example, from a doorbell).
• Connect it in the gap between S i C.
• Hold the button for 1-2 seconds when starting, then release.

Check the winding resistance with a multimeter|Disconnect the refrigerator from the mains|Prepare insulating tape|Is there a spare fuse?-->

Critically important: after startup compressor impossible leave the starting winding connected. If you forget to turn it off, the winding will burn out in 10-30 seconds. In the best case, the thermal protection will work, in the worst case, the compressor will fail.

⚠️ Attention: If the compressor is humming after direct connection not. starts, immediately turn off the power. This is a sign of an interturn short circuit or a jammed rotor. Further attempts to start will aggravate the breakdown.

4. Step-by-step instructions: connect the compressor bypassing the relay

For work you will need:

• 🔧 Screwdriver (Phillips and flathead).
• 📊 Multimeter (for checking windings).
• 🔌 Wires with a cross-section of 1.5–2.5 mm² with terminals.
• 🧲 Soldering iron (if you need to unsolder the contacts).
• 🛡️ Rubber gloves (protection against electric shock).

Step 1: Removing the relay

Disconnect the refrigerator from the network. Remove the start relay from the compressor - it is secured with latches or screws. On some models (Samsung RL-33), the relay is integrated into the control board - in this case, direct connection is not possible.

Step 2: Checking the windings

Use a multimeter in ohmmeter mode:

• Resistance between C → R: should be 10–40 Ohm.
• Resistance between C → S: should be 15–50 Ohm.
• Resistance between R → S: should be the sum of the two previous values (for example, 25 + 35 = 60 Ohms).

If the readings differ greatly, the windings are damaged.

Step 3: Connection according to the diagram

Select the diagram from section 3 and assemble the circuit. For reliability, use terminals or soldering - the “twists” can get hot. Example for a circuit with a button:

Network 220V ---
|
C (common)
/ \
R S (via button)

Step 4: Test run

Plug in the refrigerator. Press the button for 1-2 seconds - the compressor should start. If it:

• ✅ It started working and turned off after 10-15 minutes - the circuit is assembled correctly.
• ❌ It hums, but does not start - check the windings or contacts.
• ⚡ Sparks or smokes - turn off the power immediately!

5. Risks and consequences of direct connection

Even if the compressor has started, long-term operation without a relay is dangerous. Here's what to expect:

• 🔥 Overheating of the windings: without protection, the starting winding heats up to 120–150°C, which destroys the insulation.
• ⚡ Increased power consumption: the compressor is running not optimal, power consumption increases by 20–30%.
• 💥 Interturn short circuit: after 1–3 months of continuous operation without a relay.
• 🚨 Fire hazard: overheated contacts can ignite the plastic parts of the refrigerator.

In service centers such repairs are considered handicraft and are often denied a warranty (even if it is still valid). For example, in refrigerators Bosch KGE39 or Electrolux ERN 1200 direct connection will void the warranty on the compressor.

⚠️ Attention: If your refrigerator is connected via voltage stabilizer, direct connection of the compressor may cause false activation of the stabilizer protection. This is due to inrush currents, which are 5–7 times higher than the rated ones.

Alternative solutions:

• 🔧 Buy universal relay (for example, Danfoss 103N0210 or Embraco ER2225) - costs 300–800 rubles.
• 🔄 Take a relay from a donor refrigerator (models with similar compressor).
• 🛠️ Contact a workshop - replacing the relay will cost 1,000–2,500 rubles (depending on the region).
📊 Have you already tried connecting a compressor without a relay?
Yes, it worked
Yes, but the compressor burned out
No, I'm afraid to take risks
I plan to try

6. Common mistakes and how to avoid them

Error 1: Incorrect identification of contacts

On compressors Embraco or Secop contacts can be marked non-standardly:

• M (main) = C (general)
• S (start) = S (startup)
• R (run) = R (working)

Always check the datasheet for the compressor model (it can be found by the number on the tag).

Error 2: Use of wires that are too thin

Wires with a cross-section of less than 1.5 mm² will not withstand the starting current (it reaches 10–15 A). This will lead to heating and melting of the insulation. The optimal choice is copper wire PVA 2.5 mm².

Error 3: Connection without grounding

The compressor housing must be grounded - if the insulation breaks down, a phase may fall on it. If your socket is not grounded, use RCD with a leakage current of 10 mA.

Error 4: Ignoring thermal protection

Many compressors (Lunard, Tecumseh) have a built-in thermal relay. If it works, the compressor will not start until it cools down (15-30 minutes). Do not try to start it earlier - this will lead to repeated operation.

Error	Consequences	How to avoid
The windings are mixed up	The compressor does not start or rotates in the opposite direction	Ring with a multimeter
Long holding of the starting winding	Burning of the S winding	Hold for no more than 2 seconds
Lack of insulation on contacts	Short circuit	Use heat shrink tube

7. Alternative ways to start the compressor

If a direct connection seems too risky, consider these options:

• 🔄 Replacing the relay with a universal one: Relays are suitable Danfoss 103N0210 (for compressors up to 1/4 hp) or Embraco ER2225 (up to 1/3 hp). Cost - from 400 rubles.
• 🔧 Repairing a native relay: Often the posistor or contacts in the relay burn out. They can be replaced (a posistor costs 50–100 rubles).
• 🛠️ Use of starting capacitor: For compressors with a power of up to 140 W, a capacitor is suitable 100–150 uF × 250V. Scheme:

  
  Network ---[Capacitor]--- S
  |
  C → R
      

• ⚡ Connection via a soft starter: Type devices PST-1C start the compressor smoothly, reducing the load on the windings. Cost - from 1,500 rubles.

For refrigerators with inverter compressors (LG GA-B419, Samsung RB-30 J3200) the only way out is to replace the control board. Direct connection here is technically impossible due to complex electronics.

What is a soft starter?

This is an electronic device that smoothly increases the voltage on the compressor at the time of startup, reducing the starting current by 2-3 times. This extends the service life of the windings and reduces the load on the network. Suitable for refrigerators that often turn off due to voltage sags.

8. FAQ: Answers to frequently asked questions

Is it possible to connect the compressor from the refrigerator Atlant directly to a 380V network?

No. All household refrigerator compressors are designed for 220V single-phase network. Connecting to 380V will lead to instantaneous burnout of the windings. For three-phase networks, special industrial compressors are needed (for example, Bitzer or Copeland).

How long can you work without a relay?

Maximum 2-3 hours with breaks for cooling (15-20 minutes every hour). Longer - only if you are prepared for the risk of compressor failure. Ideally, no more than 30-60 minutes for diagnostics.

Why does the compressor start, but after 5 minutes it turns off?

There may be reasons. such:

1. Tripped thermal protection (compressor overheated).
2. Low voltage in the network (less than 190V).
3. Motor jammed due to wear (the compressor needs to be replaced).

Check the voltage with a multimeter and let the compressor cool for 30 minutes.

Can I use a relay from another refrigerator?

Yes, if:

• The power of the compressors is the same (check tags).
• The type of relay is the same (current or posistor).
• The contacts are suitable for location.

For example, a relay from Indesit C132 is suitable for Atlant MHM 1705if both compressors by 1/5 hp.

What to do if, after direct connection, the compressor does not start?

Possible causes and solutions:

• 🔌 No contact —check the wires and terminals.
• 🔄 Motor jammed —turn the compressor shaft with a screwdriver (through the receiver).
• ⚡ The winding has burned out —call with a multimeter (resistance should be 10–50 ohms).
• 🛡️ Protection has tripped —wait 15–20 minutes and try again.