The refrigerator compressor hums, but does not start: reasons and repair

Have you noticed that the refrigerator has stopped freezing, and the compressor, instead of the usual uniform hum, makes a prolonged hum, but does not start? This problem occurs in models of all brands - from Indesit i Atlant to premium ones Liebherr i Samsung. In 80% of cases, the malfunction is associated with an electrical part or a refrigerant leak, but sometimes trivial things like an overloaded socket or incorrect installation are to blame.

In this article we will look 7 main reasonswhy the compressor hums but does not start - from simple ones (which you can fix yourself) to complex ones (requiring the intervention of a technician). You will also learn how to diagnose a breakdown based on indirect signs, what sounds should alert you, and what to do first so as not to aggravate the situation. For clarity, we present a table of typical symptoms and their probable causes, and at the end we will answer frequently asked questions in FAQ format.

1. Start Relay Failure: The Most Common Culprit

The start relay is a small unit (usually black or gray) that attaches directly to the compressor. Its task is close the circuit at the moment the motor starts, supplying current to the winding. If the relay fails, the compressor will hum (since voltage is applied to it), but will not be able to start working due to the lack of a starting pulse.

How to recognize a broken relay:

• 🔊 The compressor makes noises uniform hum 2–5 seconds, then clicks and goes silent (the cycle repeats).
• 💡 The light inside the refrigerator is on, but there is no cooling.
• ⚡ When you touch the relay body with your hand, you can feel intense heating (evidence of a short circuit).

What to do? In most models (Biryusa, Stinol, Ariston), the relay is removable - you can replace it yourself. To do this:

1. Disconnect the refrigerator from the network.
2. Remove the protective cover from the compressor (usually attached to 1-2 screw).
3. Carefully disconnect the relay (do not pull the wires!).
4. Install a new relay of the same model (the part number is indicated on the body of the old one).

If after replacing the relay the compressor started working, but after a few days the problem returned, the reason may lie in turn-to-turn short circuit of the motor windings - here professional diagnostics will be required.

2. Problems with the capacitor: why it fails

The capacitor (aka starting capacitor) works in conjunction with a relay and is responsible for creating an additional current pulse when the compressor starts. If it malfunctions, the motor cannot overcome the initial resistance and “freezes” in humming mode. This breakdown is typical for refrigerators with inverter compressors (for example, LG DoorCooling+ or Samsung Digital Inverter).

Signs of a faulty capacitor:

• 🔋 The compressor hums quieter than usual, but does not start.
• 🔄 After turning off the power for 10-15 minutes, the refrigerator may start working for a short time.
• 🛠️ On the condenser body visible swelling, drips or corrosion.

To check the capacitor you will need a multimeter. Switch it to capacitance measurement mode (F) and connect the probes to the terminals of the capacitor. If the readings differ from the nominal value (indicated on the case) by more than 20%, the part must be replaced. For example, for a 25 µF capacitor, the permissible range is 20–30 uF.

Check visually for swelling or drips|

Measure the capacitance with a multimeter|

Compare the readings with rating on the case|

If the deviation is >20%, replace the capacitor -->

Important: capacitors accumulate charge even after the power is turned off! Before checking discharge it, short the terminals with a screwdriver with an insulated handle.

3. Freon leak: when the compressor is running "idle"

If the compressor is humming, but the refrigerator is not cooling, it is possible refrigerant leak (freon) In this case, the motor starts, but due to the lack of freon in the system, it runs without freon. load - therefore it is heard unusually quiet hum without characteristic vibrations.

Indirect signs of a leak:

• ❄️ Condenser (grid on the back wall) room temperature (should normally heat up).
• 🧊 The freezer is thawing, and there is no frost on the back wall of the refrigerator.
• 🔍 Oil stains are visible stains on the tubes or compressor (freon circulates along with the oil).

Freon leakage is one of the most serious breakdowns, as it requires a complete recharge of the system search for the location of the damage. Most often, the tubes are damaged:

• 🔧 In case of careless transportation or installation.
• 🐭 From rodents (mice and rats often chew through aluminum tubes).
• 🕰️ From corrosion (in refrigerators older than 10 years).

How to temporarily preserve food if there is a freon leak?

If the refrigerator does not work, and the repairman will arrive only after a few days, move perishable food to a cool place (for example, on the balcony in winter) or use a refrigerator bag with cold batteries. Do not put food in the freezer - without freon, it will not maintain the temperature.

Please note: refilling freon - a procedure that requires special equipment and certification. On your own this is impossible to do (and it is dangerous: freon under pressure can cause frostbite to the skin). The average cost of the service is from 3,500 to 7,000 rubles, depending on the model.

4. compressor windings

If the compressor hums but does not start, and at the same time relay and capacitor. are operationalthe problem may be in the motor itself - namely in turn-to-turn short circuit or a break in the windings. This breakdown often occurs due to:

• ⚡ Frequent power surges in the network.
• 🔥 Overheating of the compressor (for example, if the refrigerator was standing close to the battery).
• 🕰️ Natural wear (compressor service life is 10–15 years).

How to diagnose:

1. Disconnect the refrigerator from the network.
2. Remove the starting relay and capacitor.
3. Measure the resistance with a multimeter in ohmmeter mode between the compressor terminals:
   • Between C (common) and S (start winding) — there should be ~20–30 Ohms.
   • Between C and R (working winding) — ~10–15 Ohm.
   • Between S and R —the sum of the two previous values (~35–45 Ohms).

If the resistance between the terminals S–R is less than the sum of C–S i C–R, this indicates an interturn short circuit. In this case, the compressor must be replaced - it cannot be repaired. The cost of a new compressor with installation starts from 8,000 rubles (for models Nord or Pozis>) and reaches 20,000 rubles (for Bosch or Electrolux).

📊 What kind of refrigerator do you have?

Single-chamber

Double-chamber with one compressor

Two-chamber with two compressors

Side-by-Side

I don’t know

5. Malfunction of the thermostat or control board

If the compressor does not start, but not even a hum is heardthe problem may lie in the control system. In modern refrigerators, they are responsible for starting the compressor:

• 📉 Thermoregulator (in mechanical models, for example, Minsk or ZIL).
• 🖥️ Electronic control board (in refrigerators with a display, such as Samsung RB or LG GC).

How to check the thermostat:

1. Find the thermostat (usually located inside the refrigerator compartment, under the plastic cover).
2. Remove the terminals and short them together (simulating a command to turn on).
3. If the compressor is working, the thermostat is faulty and requires replacement.

With an electronic board it is more difficult: to diagnose it you need experience and special equipment: Typical signs of a board malfunction:

• 🔄 The refrigerator spontaneously turns on and off.
• 📛 The display shows errors (for example, E1, F2 - see the instructions for decoding).
• 🔌 Does not respond to button presses or changes temperature.

The cost of replacing the control board varies from 4,000 to 12,000 rubles, depending on the model For premium refrigerators. (for example, Liebherr) you may need to order a part from Europe, which will increase the repair period to 2-3 weeks.

6. External reasons: from the outlet to the installation

Sometimes the compressor does not start due to trivial external factors that can be easily eliminated yourself. data-i="206">Outlet and power cord

• 🔌 Socket and power cord:
  • Connect another device (for example, a hair dryer) to this outlet - if it does not work, the problem is in the wiring.
  • Inspect the refrigerator cord for kinks, melting or damaged insulation.
• ⚡ Network voltage:
  • Use a multimeter or socket tester to check the voltage. Normal - 220–230 V.
  • If the voltage is lower 190 V or higher 250 V, the compressor may not start.
• 📏 Installing the refrigerator:
  • The compressor must be standing strictly horizontal (check level).
  • The back wall should not touch the wall - minimum gap 5–10 cm.
  • Do not place the refrigerator next to heat sources (radiator, stove, oven).

Also pay attention to climatic conditions. in an unheated room (for example, in a country house in winter), the compressor may not start due to the ambient temperature being too low. Most models are designed to operate at +16…+32°C. At temperatures below +5°C climatic conditions. data-i="233">7. Compressor jamming: when the motor is “frozen”

7. Compressor jamming: when the motor is “frozen”

In rare cases, the compressor may jamming —that is, its shaft stops rotating due to mechanical blocking. This happens for the following reasons:

• 🛢️ Thickened oil (if the refrigerator has not been used for a long time or was stored at sub-zero temperatures).
• 🔩 Ingress of foreign particles into the mechanism (for example, after unqualified repairs).
• 🔥 Overheating and deformation of bearings (due to prolonged operation without stops).

How to diagnose jamming:

1. Disconnect the refrigerator from the network.
2. Try to manually rotate the compressor shaft (to do this, remove the protective cover and carefully turn the pulley clockwise arrow).
3. If the shaft does not rotate or requires significant effort, the compressor is jammed.

What to do? In most cases, a jammed compressor cannot be repaired it will have to be replaced, however, if the problem is thickened oil, you can try to “unwrap” the motor:

1. Disconnect the refrigerator from the network for 24 hours.
2. Place it in a warm room (for example, next to the battery).
3. After a day, try turning it on again.

What to do first: step-by-step instructions

If your refrigerator hums but does not start, follow this algorithm:

1. Check the power:
   • Make sure the plug is firmly inserted into the socket.
   • Check the voltage in the socket with a tester.
2. Inspect the compressor:
   • Remove the back cover and check that whether the relay is overheated.
   • Listen for clicks (a sign of a faulty relay).
3. Diagnose the capacitor:
   • Check it with a multimeter for capacity.
   • Inspect for swelling.
4. Evaluate the operation of the thermostat:
   • Close the thermostat terminals - if the compressor works, replace the thermostat.

Check for the presence of freon:

• The condenser (grid at the back) should be warm.
• If it is cold, a leak is likely.

If all of the above steps did not help, most likely the problem is in turn-to-turn short circuit or compressor jamming —here you can’t do without a repairman.

Check the outlet and power cord|

Inspect the compressor for overheating|

Listen to sounds (humming, clicking, crackling)|

Measure the voltage in the network|

Check the temperature of the condenser-->

FAQ: Frequently asked questions about a non-working compressor

❓ The refrigerator is humming, but not freezing - what can it do? be?

If the compressor is humming, but there is no cooling, the most likely reasons are:

• Freon leakage (the condenser is cold, the motor is idling).
• The compressor is jammed (the shaft does not rotate, a quiet hum is heard).
• Malfunction of the thermostat (the compressor turns on for a few seconds and turns off).

For an accurate diagnosis, turn off the refrigerator, wait until the compressor cools down, and try to start it again. If the situation repeats, call a technician.

❓ Is it possible to replace the compressor yourself?

Theoretically, yes, but in practice it is difficult and dangerous. To replace the compressor you need to:

1. Drain the remaining freon (special equipment is required).
2. Unsolder the tubes from the old compressor and solder them to the new one (you need a burner and solder).
3. Fill the system with freon and check for leaks (you need a manifold and a leak detector).

Without experience, you risk damaging a new part or allowing a freon leak. It is better to entrust this work to a professional.

❓ How much does it cost to repair if the compressor hums but does not start?

The cost of repair depends on the reason:

Breakage	Cost of repair (rub.)
Replacement of the starting relay	1 500–3 000
Replacement of the capacitor	1 200–2 500
Replacement thermostat	2 000–4 000
Elimination of freon leakage + refilling	3 500–7 000
Replacement of the compressor	8 000–20 000

Prices do not include the cost of parts. In regions, the cost may vary by 15–20%.

❓ How to extend the life of a compressor?

To make the compressor last longer:

• 🔌 Use voltage stabilizer (especially in rural areas or old houses).
• 🧹 Regularly clean the condenser from dust (once every 6 months).
• 🕰️ Do not place the refrigerator close to the wall - provide ventilation gap 5–10 cm.
• ❄️ Do not overload the freezer - this increases the load on the compressor.
• 🔄 Defrost the refrigerator at least once every year (even if it has a No Frost system).

❓ Can the compressor not start due to overload with products?

Yes, but only indirectly. Overloading with products in itself will not damage the compressor, but it can lead to:

• 🔥 Motor overheating due to long-term operation without stopping.
• 🧊 Freezing of the evaporator, which worsens heat transfer and causes the compressor to wear out.
• 📉 Power surges online (if the refrigerator is connected to a weak socket along with other appliances).

If the compressor does not start immediately after loading a large amount of warm food, let the refrigerator “rest” 1–2 hour, then try turning it on again.

If none of the tips helped, or you are not confident in your abilities, do not take risks. Improper repair can lead to more serious breakdowns, for example, to breakdown of the windings on the body (which is life-threatening) or depressurization of the system (which will make repairs much more expensive). Contact the service center - most technicians come to your home within 24 hours.