Fridge making noise or not cooling: what to check before calling a technician
The fridge hums or will not cool, and the first thought is a technician. Yet two of the three most worrying symptoms are already written on the appliance's datasheet: we read 48,139 records of the European registry, the Bosch manual and the self-repair document to work out when it really is a fault.
In this guide (7)
The fridge hums, clicks, gurgles. Or the milk simply is not as cold as it should be. The first thought is to call a technician, who gets paid even when there is nothing to repair. The second thought, the right one, is to open your appliance's datasheet: two of the three symptoms that worry people most are already written there, with a number next to them.
We at PortosEunostos downloaded the European EPREL registry, 48,139 domestic fridges and freezers, and placed it next to the user manual and the self-repair document Bosch publishes for its models. What comes out is a list of checks that cost nothing and take five minutes.
It is noisy: first look at how many decibels it declares
The noise of a fridge is not a matter of opinion, it is mandatory data. Every model declares its airborne acoustical noise emission in dB(A) in the European registry, along with the matching class, using the thresholds of Regulation (EU) 2019/2016: A below 30 dB, B from 30 to 36, C from 36 to 42, D from 42 upwards.
Across the 48,139 domestic appliances in the registry the median is 39 dB(A) and half the market sits between 38 and 41. Above all: 36,311 models, 75.4%, are in class C. Three fridges out of four share the same letter, so the class tells you almost nothing and the only useful number is the decibels.
In practice: if your appliance declares 39 or 40 dB and sounds loud to you, it is not faulty, it is squarely within the market norm. The comparison has to be made against its own rating plate, not against someone else's kitchen. And it is not a matter of price: in the sample of 62 Bosch and Siemens models we track in the catalogue, the Bosch KGN36NLEA at 695.69 euros and the Siemens KA93DAIEP at 2,476.07 euros declare the same 42 dB and the same class D. Three and a half times the price does not buy silence.
Position matters more: across those 62 models the median for built-in units is 35 dB against 39 dB for free-standing ones.
The noises the manufacturer calls "no fault"
The troubleshooting table in the Bosch manual for a 60 cm combined fridge-freezer lists twelve symptoms. In four cases the manufacturer's answer is literally "No fault", and they are exactly the four that make most people pick up the phone:
Gurgling, humming, clicking and creaking. It is the refrigerant in the pipes, the motor and the solenoid valves switching in and out, the automatic defrost doing its job.
The compressor starts more often and stays on longer. Modern appliances have several power levels and switch on frequently precisely in order to consume less.
Frost on the rear wall of the fridge compartment. It defrosts itself at regular intervals, as we explain in the comparison between No Frost and static.
The side panels are warm. The side walls carry pipes that heat up during cooling, and the furniture next to them is not damaged.
When the noise is new and mechanical, the manual points to four causes you can check in two minutes: the appliance is not level, the minimum clearances are not respected, pull-out parts are badly seated, bottles or crockery are touching each other.
It is not cooling: check the temperature of the room
Here is the fact almost nobody knows. Every fridge declares a climate class, that is the ambient temperature range within which it guarantees the storage temperatures in all compartments. The regulation defines four: SN from 10 to 32 degrees, N from 16 to 32, ST from 16 to 38, T from 16 to 43. Only one, SN, goes below sixteen degrees.
In the registry, 20,057 models out of 48,139, that is 41.66%, do not declare the SN class: their minimum is 16 degrees. An appliance like that, put in a garage, a cellar, a porch or an unheated second home, is not faulty in winter, it is out of specification. The thermostat reads a cold room, the compressor barely runs and the freezer warms up.
The function that solves this is called the winter setting switch, which the regulation defines as usable below 16 degrees. 1,632 models have it, 3.39%, and among the non-SN models, the ones that need it most, only 3.82%.
One honest qualification: across the 62 Bosch and Siemens models we track in the catalogue, all 62 declare the SN class and twelve also have the winter switch, all twelve of them built-in. The 16 degree risk is real but it depends on the model, and it should be read on the datasheet rather than taken for granted.
The checks that solve it without calling anyone
In order, from the most trivial to the least obvious.
Demo mode. If the appliance is not cooling but the display and interior light are on, the Bosch has showroom display mode active. You disable it by holding the temperature button for five seconds, then switching off and on again. It is the first entry in the troubleshooting table.
Time. After switching on, the appliance can take several hours to reach the set temperature. Before then it should not be loaded and should not be judged.
The ventilation grilles. Blocked at the front or the back, they make the compressor work longer and raise the internal temperature. It is the cause the manual repeats most often.
The door. Audible alarm, a seal that does not close, items blocking the door. The manufacturer has to supply you with the door seal for ten years.
A restart. If the temperature deviates significantly from the setting, the manual prescribes switching off, waiting five minutes and switching back on.
Manually defrosting the evaporator. If a No Frost unit no longer reaches temperature, the evaporator may be heavily iced: unplug it and leave the door open, and after about twenty minutes water starts draining into the evaporation tray.
When you really do need a technician
The dividing line is drawn by the manufacturer itself. The BSH self-repair document for refrigeration contains eighteen procedures: door seal, handle, four types of hinge, shelves, bottle rack, door racks, drawers and five jobs on the LED lighting. The first thirteen are within reach of whoever uses the appliance, the five on the LEDs are explicitly reserved for customer service or authorised technicians.
Above all, none of the eighteen touches the refrigerant circuit. That is not an oversight: Regulation (EU) 2019/2019 only requires manufacturers to supply end users with door handles, hinges, trays and baskets for seven years and door gaskets for ten, while thermostats, sensors, printed circuit boards and light sources go to professional repairers only. If the fault is there, the phone call is justified.
PortosEunostos advice
What to check on the product. The E-Nr code on the internal rating plate, which you need to order any spare part. The climate class, even before the energy class, if the appliance does not live in a heated kitchen. The declared decibels, not the letter: it is one of the three parameters in our buying guide. And the annual consumption, because a compressor that never stops shows up on the bill before it shows up in a workshop.
How to judge the seller. Ask whether they handle warranty service directly or pass it to the manufacturer, and how much a technician call-out costs outside the warranty. Comparing the same model code across several shops remains the fastest way to see what it is really worth: on SniffaPrezzi the offers sit side by side, while the datasheets and availability of the models we mention are on OpportunityCommerce.
If the check ends with a quote in your hand, the next question is whether repairing is worth it: we put that into numbers in how long a fridge really lasts and in what it really costs to repair an appliance. For the maintenance that prevents half of these symptoms there is how often to defrost and clean the refrigerator.
Read next: if the doubt concerns the freezer compartment, the numbers to check are the target temperature, the freezing capacity and the hours of autonomy without power: Freezer temperature: what 18 below zero means and how long food lasts.
Sources
European EPREL registry, refrigerating appliances group: 56,419 records downloaded on 26 October 2026, 55,397 unique, 48,139 domestic fridges and freezers once wine storage appliances are excluded.
Regulation (EU) 2019/2016: airborne acoustical noise emission classes (table 2), definition of climate class and of winter setting switch, SN, N, ST and T ranges.
Regulation (EU) 2019/2019, annex II section 3: spare parts available to end users and to professional repairers only.
Bosch KGN3 series user manual, chapter 14 on troubleshooting and the criteria for the installation location.
BSH, Self-repair hints for refrigerating appliances: eighteen procedures and their warnings.
Official Bosch website, KGN36NLEA product page and spare parts search.
OpportunityCommerce prices read on 26 October 2026 on the product pages of the models mentioned.
