Why the refrigerator knocks at night: dangerous and harmless reasons

The night knock of the refrigerator can unsettle even the most patient owner. In the silence of the bedroom, every click, creak or rhythmic beat seems ten times louder. But before you call a technician or urgently look for replacement equipment, figure it out: not all sounds signal a breakdown. Modern refrigerators (even models with the system No Frost) emit a whole range of operating noises - from a barely audible hum to distinct mechanical shocks.

In this article we will analyze in detail 7 main reasons for night knocking - harmless features structures to serious faults requiring repair. You will learn how to distinguish normal noise from an alarm signal, what manipulations you can do yourself, and when it’s time to call a specialist. We will pay special attention to models Samsung, LG, Indesit i Atlant —their “weak points” often become a source of night discomfort.

1. Compressor operation: why does it knock like a clock

The compressor is the “heart” of the refrigerator, and its rhythmic sounds are inevitable. In 80% of cases, it is he who is to blame for the knocking at night. But how do you understand that this is normal operationand not a harbinger of a breakdown?

In modern models (for example, Samsung RB37J5240SA or LG GA-B489YDQZ) compressors are often equipped with inverter control. They automatically regulate power, which leads to:

• 🔊 Clicks when turned on/off (the starting relay is activated).
• ⚙️ Rhythmic vibrationtransmitted to the body (if the refrigerator is not level).
• 💥 Thud knocks with a sudden change in load (for example, after opening the door).

⚠️ Attention: If the compressor knocks every 5-10 seconds without pauses or the sound has become sharper than usual - this is a sign wear of shock absorbers or problems with the relay. In this case, diagnostics are required.

2. Thermal expansion: why the refrigerator “shoots”

Metal and plastic parts of the refrigerator expand when heated and contract when cooled. This process is accompanied crackling, crackling or light impacts - especially noticeable in silence. Most often they “shoot”:

• 🧊 Condenser tubes (on the back wall).
• 🔄 Plastic guides doors (if the seal is worn out).
• ❄️ Ice in the freezer (during No Frost or manual defrosting).

🔹 How to reduce noise?

1. Check the gap between the door and the body —it should be uniform.
2. Make sure that the refrigerator is not close to the wall (the minimum gap is 5 cm).
3. If the model is with No Frost, defrost it for 12–24 hours (ice build-ups can put pressure on parts).

3. Fan No Frost: creaking and knocking of blades

Refrigerators with a system No Frost (LG GA-B429SLGL, Bosch KGE39AW20Rare equipped with a fan that distributes cold air. If it starts knocking, the reasons may be as follows:

⚠️ Attention: If the fan knocks continuously and the refrigerator does not freeze well, this is a sign of icing on the evaporator. In this case defrosting should last at least a day, otherwise the problem will return.

What happens if you ignore the knock fan?

If the cause is not eliminated, the fan may jam, which will lead to overheating of the compressor and failure of the control board. In models Samsung s Digital Inverter this is fraught with expensive repairs (from 8,000 ₽).

4. Incorrect installation: vibration and “walking” body

Even a new refrigerator will knock if it is not level. It’s easy to check:

1. Place it on the top lid of the refrigerator level (or a glass of water).
2. If the bubble is displaced or the water overflows, adjust front legs (they are usually have threads).
3. Check whether the case is touching furniture or wall (vibration increases with contact).

🔹 Typical installation errors:

• 🚫 The refrigerator stands on uneven floor (linoleum, carpet).
• 🚫 The back wall touches pipes or sockets.
• 🚫 Inside the chamber the shelves are overloaded (vibration increases).

Adjust the legs to the level|

Make sure that the back wall does not touch the furniture|

Check the gaps between the door and the body|

Remove heavy objects from the top cover-->

5. Problems with the starting relay: clicks and knocks

If the refrigerator knocks rhythmic (for example, every 3-5 seconds) and at the same time does not cool, the starting relay is to blame. This unit is responsible for starting the compressor, and its malfunction manifests itself as follows:

• 🔊 Loud clicks (the relay tries to start the compressor, but cannot).
• 💥 Shocks (if the relay contacts are “sticky”)
• ❌ The compressor does not turn on or works in jerks.

🔹 How to diagnose?

1. Disconnect refrigerator from the mains for 10 minutes.
2. Turn it on again and listen: if the clicks are repeated, the relay is faulty.
3. In models Indesit i Atlant the relay often “sticks” due to overheating Check to see if it is hot to the touch.

⚠️ Attention: You can only replace the relay yourself if you have experience! In refrigerators LG s Linear Compressor incorrect installation of the relay can lead to compressor combustion.

6. Wear of compressor shock absorbers: dull knock

Shock absorbers (rubber cushions) dampen vibration of the compressor. Over time, they harden or crack, and then each cycle of work is accompanied dull knocks, similar to beating on a drum.

🔹 Signs of shock absorber wear:

• 🔊 The knocking intensifies when starting or stopping the compressor.
• 📦 The refrigerator “bounces” during operation (you can see it if you look closely).
• 🛠️ On the back wall you can see cracks on the rubber supports.

🔹 How to fix?

1. Disconnect the refrigerator and carefully move it away from the wall.
2. Inspect the shock absorbers (they are bolted to the compressor).
3. If the rubber is cracked, replace the cushions (cost from 200 ₽ per piece).

7. Foreign objects: why the refrigerator rattles like a rattle

Sometimes the source of the knocking lies on the surface - literally. Inside the refrigerator or behind its walls there may be:

• 🥛 Glass jarstouching each other.
• 🧊 Icefalling from the freezer shelves.
• 📦 Plastic containersvibrating from compressor operation.
• 🐭 Rodents or insects (if the refrigerator has been turned off for a long time).

🔹 How to check?

1. Turn off the refrigerator and carefully inspect internal shelves.
2. Shake the refrigerator on the side - is there something rattling inside the walls?
3. Check rear grate (sometimes small objects fall there).

⚠️ Attention: If you suspect that there are rodents in the refrigerator, do not turn it onuntil you make sure there is no damage to the wiring! Mice often chew through the insulation, which can lead to a short circuit.

FAQ: Frequently asked questions about the refrigerator knocking at night

❓ The refrigerator knocks only at night - why is it quiet during the day?

At night the knocking is more audible because of the silence, but there are also objective reasons:

• The temperature in the room drops → the compressor works more intensely.
• During the day, vibration is drowned out by household noise (TV, conversations).
• In some models (Samsung c Eco Mode) at night, an energy-saving mode is activated, which changes the rhythm of the compressor.

❓ Is it possible to repair a knocking compressor yourself?

You can replace shock absorbers or clean the fan yourself, but:

• 🛠️ Relay and compressor it is better to entrust it to a specialist - you need a soldering iron and a tester.
• ⚠️ In refrigerators LG with 10-year warranty on the compressor, independent repairs will void the warranty.
• 💰 The cost of diagnostics in the service is from 1 500 ₽, compressor replacement - from 6 000 ₽.

❓ What noise is considered normal for refrigerator?

Acceptable sounds (according to GOST R 51318-99):

• 🔊 Compressor hum (25–45 dB).
• 💨 Fan noise (in models with No Frost).
• 🔄 Relay clicks (1-2 times at startup).
• 🧊 Plastic crackling when the temperature changes.

🚨 Alarming sounds: metal grinding, continuous knocking, humming with vibration housing.

❓ A new refrigerator is knocking - is it a defect?

Not always. In the first 1–2 weeks after purchase, the refrigerator may knock due to:

• 🆕 Lapping in parts (compressor, fan).
• 🏠 Incorrect installation (legs not adjusted).
• 📦 Transport boltsthat they forgot to remove (check instructions!).

If the knocking does not go away after a week, contact the service center (warranty is usually 1-3 years).

❓ Can the knocking of a refrigerator be dangerous?

The knocking itself is not dangerous, but it can signal problems that lead to:

• ⚡ Fire danger (if the relay is knocking due to a short circuit).
• 💸 Increased energy consumption (the compressor operates in emergency mode).
• ❄️ Product spoilage (if air circulation is disrupted due to knocking).

🔹 When do you urgently need a repairman? If the refrigerator is knocking + does not freeze, or an error is shown on the display (for example, E1 v Indesit).