How to independently test a refrigerator without a relay for functionality: instructions with photos and diagrams

The refrigerator has stopped freezing, but there is no start relay at hand, and the technician will arrive only in a week? Or do you suspect that the problem lies not in the relay, but in the compressor itself or the electrical circuit? In this article we will look at how to check a refrigerator without a relay from diagnosing the motor windings to testing the pressure in the system. You don't need expensive tools: just a multimeter, a screwdriver and basic knowledge of electrical engineering.

The absence of a relay complicates the task, but does not make it impossible. The main thing is to understand the principles of operation of the refrigeration unit. The compressor should normally start directly if the correct voltage is applied to it. However Without a relay, you cannot leave the system on for a long time: this is fraught with overheating of the windings. All tests are carried out for a short time, with the obligatory shutdown of power between checks.

We will consider methods for refrigerators Atlant, Indesit, Stinol, Biryusa and other popular brands. We will pay special attention typical mistakesthat beginners make when testing without a relay - for example, ignoring insulation resistance or incorrectly connecting contacts.

1. Preparation for diagnostics: safety precautions and tools

Before checking the refrigerator without a relay, de-energize it and wait for complete defrosting (if the unit was turned on). Working with a compressor under voltage is dangerous - there is a risk of electric shock or short circuit. You will need:

• 🔧 Mulmeter (to check winding resistance and voltage).
• 🔌 Insulated wires with terminals ("crocodiles") for temporary connection.
• 🔨 Screwdriver (cross/flat) for removing the compressor protective casing.
• 📏 Pressure tester (optional, for checking the refrigerant).

If you inverter compressor (installed in models Samsung No Frost, LG Door-in-Door etc.), the verification methods will be different - such motors will not start without an electronic control unit. They require specialized equipment.

⚠️ Attention: Do not touch the metal parts of the compressor when applying voltage. Even after disconnection, capacitors can retain a charge of up to 300 V!

Before starting work, photograph the location of all wires and terminals on the compressor. This will help avoid errors during reassembly. If the refrigerator is under warranty self-diagnosis may void it -take this into account.

2. How to check the compressor windings without a relay

The refrigerator compressor has three terminals: C (common), S (starting winding), R (working winding). Without a relay, we can check the integrity of the windings and the absence of a short circuit to the housing. To do this:

1. Remove the protective casing from the compressor (usually secured with 3-4 bolts).
2. Disconnect all wires from the compressor contacts.
3. Switch the multimeter to resistance measurement mode (200 Ohms).

Now measure the resistance between conclusions:

If the resistance between S → R is not equal sum C→S i C→R, this indicates interturn short circuit. For example, if C→S = 30 Ohm, C→R = 15 Ohm, and S→R = 35 Ohm (instead of 45 Ohm), the windings are closed.

⚠️ Attention: In compressors Danfoss (installed in Electrolux, Zanussi) the normal resistance of the starting winding can reach 50 Ohm. Check the technical data of your model!

Disconnect the refrigerator from the mains

Remove the compressor casing

Disconnect all wires from the terminals

Measure resistance C→S, C→R, S→R

Check the resistance to the body (should be ∞)

Check the results with the table -->

3. Direct start of a compressor without a relay: diagram and risks

If the windings are working properly, you can try to start the compressor directly, simulating the operation of a relay. To do this, briefly (no more than 3 seconds!) apply voltage to the working and starting windings. Connection diagram:

• 🔌 Connect C (common) to neutral wire 220V network.
• 🔌 Connect R (working winding) to phase wire.
• 🔌 Short term (for 1-2 seconds!) connect S (starting winding) to R.

If the compressor started and began to hum, the problem was in the relay. If not, the following malfunctions are possible:

• 🔴 Piston jamming (the compressor does not rotate, a click is heard).
• 🔴 Insufficient refrigerant pressure (the compressor hums, but does not pump).
• 🔴 Open circuit in the thermostat (power is not supplied to the compressor).

Under no circumstances keep the starting winding connected for more than 3 seconds - this will lead to overheating. If the compressor does not start on the first try, repeat the test at intervals of 5 minutes.

4. Checking the pressure in the system: signs of freon leak

If the compressor starts, but the refrigerator does not freeze, it is possible refrigerant leak or clogged capillary tube. This can be checked by indirect signs and direct measurements:

• 🔍 The condenser does not heat up (the tube on the back wall remains cold).
• 🔍 The compressor works without stopping, but the temperature in the chamber does not drop.
• 🔍 The oil in the compressor has darkened (visible through the inspection window).

For accurate diagnosis needed gauge manifold. Connect it to the service port (usually located on the filter drier). Normal indicators:

• 🟢 Suction pressure (blue tube): 0.2–0.8 bar.
• 🔴 Discharge pressure (red tube): 8–15 bar.

If the discharge pressure is below 6 bar, this indicates lack of freon or compressor wear. If the suction pressure is close to 0 - clogging in the capillary tube.

⚠️ Attention: Working with freon requires certification! Self-charging refrigerant (for example, R134a or R600a) without experience is dangerous - there is a risk of poisoning or explosion.

What to do if the pressure is normal, but the refrigerator does not freeze?

In this case, check:

1. Thermostat - it may not give a signal to turn on the compressor.

2. Fan No Frost (in models with a dry freezing system) - if it is broken, the cold does not enter the chamber.

3. Current leakage to the body —measure the resistance between the plug and the metal parts of the refrigerator (should be ∞).

5. Diagnostics of the electrical circuit: from the plug to the compressor

Often the problem lies not in the compressor, but in open power circuit. Ring all elements in order:

1. Power cord and plug —check for open circuit with a multimeter.
2. Thermostat —in the "Max" position, the resistance should be 0 Ohm.
3. Fuse (if any) - must pass current.
4. Defrost button (in models with No Frost) - when pressed, the circuit is closed.

To check the thermostat:

1. Remove the temperature control knob.
2. Disconnect the wires from the contacts.
3. Ring the contacts 3 and 4 (usually common and output to the compressor).

If the thermostat does not ring in any position, it needs to be replaced. Models Atlant and Stinol often use a thermostat K-59 or TAM-133 —they can be purchased separately.

6. Typical malfunctions that are disguised as a “burnt out relay”

Many users mistakenly believe that if the refrigerator does not turn on, the relay is to blame. In fact, similar symptoms give:

• 🔌 Faulty line filter (in modern models LG, Samsung).
• ❄️ Stuck fan (in systems No Frost blocks the compressor starting).
• 🔥 Burnt capacitor in the power circuit (often in refrigerators Indesit over 10 years old).
• 🛠️ Oxidized contacts on the compressor terminals (cleaned with sandpaper).

To eliminate these malfunctions:

1. Check whether the fan rotates manually (with the power off!).
2. Inspect the capacitor for swelling or electrolyte leaks.
3. Ring the line filter (the resistance between the input and output should be minimal).

If the refrigerator clicks, but does not startit may be:

• 🔊 Faulty start-up relay (yes, even if you turned off).
• 🔊 Stuck compressor (piston does not move due to mechanical blockage).
• 🔊 Thermal protection triggered (compressor overheated and turned off).

7. When to call a repairman: 5 signs of a serious breakdown

Not all faults can be repaired yourself. Contact a specialist if:

• 🚨 Compressor hums, but does not create pressure (sure sign) wear of the piston group).
• 🚨 Cracks or oil leaks appeared on the compressor housing cracks or oil leaks.
• 🚨 Refrigerator electric shock when you touch the case.
• 🚨 After starting without a relay, the compressor gets very hot (more than 70°C in 5 minutes).
• 🚨 There is no freon in the system The cost of repairing a compressor or replacing refrigerant in a service center starts from 3,500 rubles (for models (even after refilling).

The cost of repairing a compressor or replacing refrigerant at a service center starts from 3,500 rubles (for models Biryusa, Atlant>) and reaches 8,000 rubles (for Liebert, Bosh) In some cases it is cheaper to buy a new refrigerator - especially if the age of the old one is more than 10 years.

Remember: refilling freon yourself without vacuuming the system. will lead to a repeated leak within a year. To do this, you need a professional manifold and a vacuum pump.

FAQ: Frequently asked questions about checking a refrigerator without a relay

Is it possible to turn on a compressor for a long time without a relay?

No! Without a relay, the compressor will overheat in 5-10 minutes, which will lead to an inter-turn short circuit. The relay not only starts the motor, but also protects it from overloads. Only short-term tests are allowed. data-i="279">How to distinguish a faulty relay from a burnt-out compressor? (no longer than 3 seconds).

How to distinguish a faulty relay from a burnt out compressor?

If, with a direct connection (see section 3), the compressor starts and hums, the problem is in the relay. If it does not respond at all (no clicks, hum), the compressor is faulty or there is a break in the windings. Also check the resistance of the windings (section 2). data-i="281">Why does the compressor start, but the refrigerator does not freeze?

Why does the compressor start but the refrigerator does not freeze?

Probable causes:

• Freon leak (check the pressure, section 4).
• Clogged capillary tube (condenser is cold, compressor is hot).
• Faulty thermostat (does not give a command for continuous operation).
• Broken fan No Frost (cold does not enter the chamber).

What to do if the resistance of the windings is not normal?

If resistance:

• Too high (∞) —winding break. The compressor needs to be replaced.
• Too low (close to 0) —turn-to-turn short circuit. Also requires replacement.
• There is resistance to the housing —insulation breakdown. Life-threatening, the compressor needs to be changed.

How to check a refrigerator No Frost without a relay?

In systems No Frost The testing algorithm is more complicated:

1. Check the fan (should rotate freely).
2. Make sure that the defrost heater is working (resistance 20–50 Ohms).
3. Ring the defrost sensor (at room temperature the resistance is ~5 kOhm).
4. If the compressor does not start, check the control board (a common problem in Samsung i LG).

It is possible to start the compressor without a relay, but the control board may block operation due to sensor errors. No Frost it is possible, but the control board may block operation due to sensor errors.