Noisy refrigerator or a compressor that never stops: causes and when to call a technician

• Switch off the MCB and unplug the appliance before checking anything.
• Make sure your hands and the floor are dry.

The compressor area at the back gets hot while the refrigerator runs, and its metal edges are sharp, so wear gloves before you touch it.

A refrigerator has many moving parts, and each makes its own sound. LG Indonesia's help pages describe several normal ones. The fan inside the refrigerator circulates cold air and can hum like a desk fan. The compressor gives off heat while it runs, so a fan in the machine compartment at the back spins too, and it hums as well. The valve that switches the refrigerant flow can rattle briefly when the flow changes direction, and LG calls this normal.

The manual for the Sharp SCH-210FS cooler gives a similar list. It names a loud sound when the compressor first starts, which fades after a while, and liquid flowing like tap water in the evaporator. It also names light knocking as the inner walls expand and contract during cooling. The same manual notes that the front and sides of the cabinet feel warm. That is heat being released, not a sign of a fault.

So the real question is not whether there is a sound, but whether it has changed: louder than usual, constant with no pause, or coming with a refrigerator that is no longer cold.

1. Think about what just happened. If the refrigerator was just moved or cleaned, LG explains that the compressor and fan can run at high speed when the power comes back on. LG advises waiting at least 10 minutes before plugging it back in after moving or cleaning, because it can make abnormal noise if it is plugged in before the refrigerant has settled.
2. Check the fast cooling modes. Features such as fast freeze or fast cool run the compressor and fan at high speed. They are louder, and they turn themselves off after a set time.
3. Level the refrigerator. Open the door and turn the leveling screw underneath with the wrench that came with the refrigerator until it no longer rocks. On models with an adjustable hinge pin, LG warns against overdoing it: the height can only be adjusted by up to 3mm, and beyond that the hinge pin may come out.
4. Check the floor and surroundings. A wooden floor, or objects touching the cabinet, carry the vibration and make the sound seem louder. Leave a little space between the refrigerator and any cabinets, walls or shelves next to it.
5. Listen at the back. If the rattling comes from the machine compartment at the lower back, unplug the refrigerator, then clear away dust and loose objects you can reach without removing a screwed-on panel.
6. Sound from inside the refrigerator. If the fan inside hums and rattles, LG says something may be blocking it or its motor may have frozen. Unplug the refrigerator and let the ice melt; LG estimates this takes about one day in summer.

A compressor normally cycles on and off: it starts when the temperature inside rises and stops once the set temperature is reached. If it almost never stops, the refrigerator is either losing cold air all the time or cannot get rid of its heat. Most of the causes lie outside the compressor itself.

• The door is opened often or does not seal. The Sharp manual warns that opening the door often raises both the temperature inside and the power use. Make sure the door seal is clean and nothing props the door open.
• Too much food. LG advises keeping the refrigerator no more than 70% full so cold air can circulate; food that covers the vents keeps part of the inside warm.
• Too little space around the refrigerator. The Sharp SJ-U43P manual says that less space than its instructions show can raise the unit's temperature and cause loud noise and breakdowns. For that model, the gap between the back and the wall is 50mm or more, but less than 75mm.
• Hot food and a very cold setting. LG explains that the compressor runs faster for a while when the door is opened often or hot food goes inside. The coldest setting also keeps the compressor running longer.
• A hot kitchen. In a closed-in kitchen next to the stove, the heat has nowhere to go. Move the refrigerator to a more open spot if you can.

Once these points are sorted out, give the refrigerator a full day and open the door as little as possible. If the compressor still never stops, especially if the inside is not cold either, the cause is probably inside the system and needs a technician.

The same sound can be far more annoying in one home than in another. LG explains that operating sounds seem louder when the refrigerator is in a small room, and that vibration travels easily when the refrigerator stands on a wooden floor or is surrounded by household objects. In smaller Indonesian houses, the refrigerator often stands in a narrow passage by the kitchen or right against a cabinet, so its hum echoes around the room.

The Sharp SJ-U43P manual asks for the refrigerator to stand level and firm on the floor, and not in a damp or wet place. Where it would otherwise sit directly on the ground, the manual suggests a suitable stand such as a wooden board. The same manual asks you to keep the space around the refrigerator clear. Leaving a gap and making sure every foot rests on the floor often cuts the noise without taking anything apart.

Contact the authorized service center for your refrigerator's brand if any of these happens:

• humming or buzzing that is irregular or constant (LG recommends having a service technician check it);
• loud noise from the compressor that keeps coming back even though the refrigerator is level and stable;
• the compressor never stops and the inside is not cold, even though the door, contents and wall gap are all right;
• the machine compartment at the back is hard to clean yourself, or the rattling remains after cleaning;
• you smell burning, the power cord feels hot or the socket is scorched (pull the plug if it is safe to do so).

Adjusting or replacing the thermostat, a sensor or a fan, and any work on the refrigerant system, is a job for an authorized technician; none of it is taken apart at home. A hot or loose socket should be repaired by a qualified electrician.