Why the refrigerator knocks at night: dangerous and safe reasons

You wake up in the middle of the night from a rhythmic knocking coming from the kitchen, and you understand: it’s happening again refrigerator knocking. During the day, this sound may not be noticed due to everyday noise, but in silence it turns into real torture. Why does technology behave so aggressively at night? Let us reassure you right away: in 80% of cases this is not a breakdown, but a feature of the system. However, you should not ignore the knocking - it can signal an imminent failure of key components.

In this article we will analyze all possible causes of night knocking - from harmless thermal expansion of plastic to serious compressor malfunctions. You will learn how to distinguish normal noise from alarming noise, when it’s time to call a professional, and in what cases the problem can be solved on your own in 10 minutes. We will pay special attention to models with system No Frost and inverter compressors - their “behavior” at night is often confusing.

We warn you right away: if there is a knock accompanied vibration of the case, a sharp increase in temperature in the chambers or the activation of an alarm, this is a reason to unplug the refrigerator and call a specialist. In all other cases, read on - we will teach you to “talk” to the equipment in its language.

1. Thermal expansion of plastic: why the refrigerator “shoots” at night

The most harmless reason for knocking at night is deformation of plastic parts due to temperature changes. During the day, the refrigerator door opens frequently, allowing warm air to enter, and at night the appliances operate in a stable mode. The plastic used to make shelves, drawers, and seals shrinks when cooled and expands when heated. These micro-movements are accompanied by clicks or dull blows.

The effect is especially noticeable in new refrigerators (the first 1-2 months of operation) and models with thin walls (for example, ATLANT XM 4021-000 or Biryusa 106). The sound is amplified if:

• 🔹 The refrigerator is close to the wall or furniture (vibration is transmitted to the surface)
• 🔹 There is little food in the chambers (empty space enhances resonance)
• 🔹 The temperature in the room at night drops below +18°C (plastic shrinks more)

How to check? Put your ear to the case: if clicks come from the side doors or back walland not from the bottom (where the compressor is), thermal expansion is to blame. The solution is simple:

Install the refrigerator at a distance of 5-7 cm from the walls|Fill empty shelves with containers of water|Check the tightness of the seal|Use anti-vibration pads under the legs-->

⚠️ Attention: If the clicks are accompanied by a cracking sound (as if plastic is breaking), this may indicate microcracks in the body due to improper transportation. In this case, the part needs to be replaced - the plastic does not “heal” over time.

2. Compressor operation: normal noise or distress signal?

The compressor is the “heart” of the refrigerator, and its operation is always accompanied by sounds. During the day we don't notice them, but at night rhythmic knocking or humming it can seem deafening. Normal compressor sounds:

• 🔊 Double humming during startup (1-2 seconds)
• 🔊 Rhythmic vibration during operation (like "murmuring")
• 🔊 Single click when turned off

Alarm signals requiring diagnosis:

🔧 Self check: Disconnect the refrigerator from the network for 10 minutes, then turn it on again. If after starting the knocking intensifies or a metallic clang appears, this is a sign of a compressor. In models with inverter motors ( mechanical wear compressor. In models with inverter motors (LG Inverter Linear, Samsung Digital Inverter), a knock during startup often indicates a malfunction inverter module.

Once every month|Once every 3 months|Once every six months|Only when ice forms|Never-->

3. Problems with the thermostat: why the refrigerator “hiccups” at night

The thermostat (or thermostat) is responsible for turning the compressor on/off. If it malfunctions, the refrigerator may frequently switches on with a loud click, especially at night, when the temperature in the room drops. Typical symptoms:

• 🔸 Compressor starts every 5-10 minutes
• 🔸 Knocking accompanied short hum (motor turns off immediately)
• 🔸 The refrigerator compartment is too cold (food freezes)

🔍 How to check the thermostat?

1. Disconnect the refrigerator from network.
2. Remove the protective casing from the thermostat (usually located next to the temperature control knob).
3. Ring the contacts with a multimeter in resistance testing mode. At room temperature, the resistance should be 0 Ohm (the contacts are closed).

If there is no resistance, the thermostat is faulty. In models Indesit i Ariston this part costs ~1200-2500 rubles, replacement takes 20-30 minutes. In refrigerators with electronically controlled (Samsung RB30J3000WW, Bosch KGE39XW2AR) instead of a thermostat, temperature sensor is used - it is checked by voltage (should be ~5 V at +20°C).

What will happen if not change a faulty thermostat?

If you ignore the problem, the compressor will start working without stopping, which will lead to its overheating and failure in 1-3 months. The average cost of replacing a compressor is 8,000-15,000 rubles, while a new thermostat will cost 3-5 times less.

4. No Frost system: why does the refrigerator crack and knock? Normal sounds:

Refrigerators with system No Frost (Samsung RL38T6000SA, LG GA-B489YVQZ) knock at night more often than usual due to work fan and defrost heater. Normal sounds:

• 🍃 Fan noise (similar to a computer cooler)
• 🔥 Crackling when the heater is turned on (every 8-12 hours)
• 💧 Gurgling when freon moves through the pipes

Pathological sounds requiring intervention:

🛠️ How to fix it? If the refrigerator No Frost started knocking louder than usual:

1. Disconnect it from the network for 24 hours for complete defrosting.
2. Check that the fan is not blocking ice or food (in models Samsung the fan is located behind the rear panel of the refrigerator compartment).
3. Clean the drainage hole (located at the bottom of the rear wall).

5. Incorrect installation: when it is not the refrigerator that is to blame, but the floor

If the refrigerator started knocking after moving or rearranging, the problem lies in improper installation. Even a perfectly working compressor will rattle if:

• 🏠 The body is not level (misalignment more than 2°)
• 🔧 The legs are not adjusted to height
• 🪨 The floor under the refrigerator is uneven or creaky
• 🧲 The refrigerator is located next to sources of vibration (washing machine, microwave)

📏 How to level the refrigerator:

1. Use building level (place on the top cover).
2. Adjust the front legs clockwise to raise or counterclockwise to lower.
3. The rear legs are adjusted with a wrench (in most models).
4. Check that the gap between the case and the floor is at least 2-3 cm for ventilation.

⚠️ Attention: In refrigerators with inverter compressor (Hitachi R-B360P7MS, Panasonic NR-BN30AW1) vibration is transmitted to the case more strongly due to the lack of inrush currents. For them, be sure to use rubber anti-vibration pads under the legs (cost ~200-400 ₽ in spare parts stores).

6. Freon leak: when a knock is a cry for help

The most dangerous cause of a night knock is leakage of refrigerant (freon). It is accompanied not only by sounds, but also by other symptoms:

• ❄️ The refrigerator does not freeze well, despite the constant operation of the compressor
• 🔊 The knocking becomes metal and frequent (every 1-2 minutes). freon)
• 🌡️ The condenser (grid on the back wall) remains cold
• 💨 There is a smell coming from under the refrigerator burnt plastic (if oil leaks along with freon)

🔎 How to check?

1. Turn off the refrigerator and inspect places where the tubes are soldered on the back wall. Look for oil stains or rust.
2. Check capillary tube (thin copper tube) - it often rubs against the body.
3. If you find damage - do not turn on the refrigerator! Freon is under pressure, and when the compressor is running, the leak will increase.

💰 Repair cost: Fixing the leak with refilling freon will cost 5000-12000 ₽ depending on the model. In refrigerators older than 10 years (Stinol 101, Minsk 126), it is often more profitable to buy a new one, since repairs can be repeated in 1-2 years.

7. Additional sources of noise: what else could be knocking?

If you have ruled out all the above reasons, check these “unobvious” sources of knocking:

• 🧊 Ice in the drainage system —when thawing, pieces of ice fall into the pan, making loud sounds. Solution: clean the drainage hole with wire.
• 📦 Food in the refrigerator —cans or bottles can knock against each other when vibrating. Solution: use silicone linings under glass containers.
• 🪫 Dust on the condenser - a thick layer of dust impairs heat transfer, causing the compressor to work louder. Solution: clean the grill with a vacuum cleaner once every 6 months.
• 🔌 Electrical problems —voltage surges cause the compressor to “jerk.” Solution: connect the refrigerator via voltage stabilizer.

🔧 Advice for owners of two-chamber refrigerators: If knocking comes from freezer compartmentcheck the operation switch valve (in models ATLANT MHM 1705, Beko RCSK 250M00 S). Its jamming leads to water hammer in the system - the sound is similar to knocks on pipes.

What to do if the refrigerator knocks at night: step-by-step instructions

Algorithm of actions for diagnosing and eliminating night knocking:

Check whether the refrigerator is touching furniture or walls|Turn off the refrigerator for 10 minutes and listen to the sounds when startup|Inspect the compressor for oil stains|Check the temperature in the chambers (should be +4°C in the refrigerator and -18°C in the freezer)|If there is a metallic knock, call a technician-->

⚠️ Attention: If the refrigerator is under warranty, do not disassemble it yourself! Opening the seals on the compressor or thermostat will void the warranty. In this case, contact the brand's service center (LG, Samsung, Indesit etc.) with a description of the problem.

📌 When to call a technician?

• Knocking accompanied increase in temperature in the chambers
• On the back wall you can see oil stains or rust
• Compressor works non-stop more than 12 hours
• Refrigerator turns off spontaneously

Average cost of a technician in Moscow and the regions:

FAQ: Frequently asked questions about the refrigerator knocking at night

❓ Why does a new refrigerator knock at night but not during the day?

In new models (ATLANT, Beko, Indesit) the first 1-2 weeks occurs "grinding in" of compressor and thermostat parts. At night the knocking is more audible due to the silence. If after a month the sounds have not decreased, check installation level and the tightness of the door.

❓ Is it possible to replace the thermostat yourself?

Yes, if you have experience working with electrician For most models (Samsung RL33E, LG GA-B379SLGL), it is enough to turn off the refrigerator, remove the control panel and replace the part (the cost of the thermostat is 800-2000 ₽). Important: before replacing, take a photo of the wiring diagram!

❓ Why does the No Frost refrigerator knock like a machine?

In systems No Frost every 8-12 hours it turns on defrost heaterwhich melts the ice on the evaporator. This process is accompanied by crackling and gurgling sounds. If the sounds become louder, check fan - perhaps its blades are touching the ice.

❓ Is it dangerous to sleep in the same room with a knocking refrigerator?

If the knocking is caused by thermal expansion or operation of a metal compressor clanging, it is safe for health, but can interfere with sleep. In the case of metallic clang or freon leaks sleeping next to each other is not recommended - headaches from oil or refrigerant vapors are possible.

❓ How to reduce the noise of a refrigerator without repair?

Try these methods:

• 🔇 Place the refrigerator on rubber mat (absorbs vibration)
• 📉 Reduce the temperature in the chamber by 1-2° (the compressor will turn on less often)
• 🚪 Check door seal —if it is worn out, the refrigerator runs louder
• 🌡️ Make sure that the rear grille does not touch the wall (there should be a gap of 5-7 cm)

If after all the checks the knocking does not disappear, do not delay the visit of the specialist. Refrigerators rarely “die” suddenly: usually they let you know about problems in advance - namely by night noise, changes in the operating cycle or mild frost. The sooner you pay attention to these signals, the cheaper the repair will cost.