How to defrost and clean a freezer: the step-by-step guide
If your freezer is NoFrost it doesn't need defrosting, if it's manual the rule is every 3-6 months or at 3-5 mm of ice. The step-by-step procedure for upright and chest formats, what never to do, and how to clean it, comparing the official guidance from Bosch and Electrolux.
In this guide (8)
If your freezer has NoFrost technology, you don't need to defrost it: that's exactly what the system does, it removes frost before it can build up. If it's a manual model, chest or upright, the rule of thumb manufacturers give is simple: defrost it every 3-6 months, or whenever the ice layer on the walls reaches 3-5 mm. Below is the step-by-step procedure for both formats, what never to do, and how to clean the appliance once you're done, NoFrost included.
NoFrost or manual defrost: how to tell which one you have
The manufacturer's spec sheet and the user manual say it without ambiguity: if "NoFrost" or "automatic defrost" appears, the circuit clears frost on its own and manual defrosting is not required. We verified this firsthand on the manual for the Bosch GIN81VEE0 already analysed on Portos: under "Defrosting the freezer compartment" it states, word for word, that "thanks to the fully automatic NoFrost system, no ice forms in the freezer" and that "defrosting by the customer is not necessary".
Re-reading the EPREL registry we use for our energy-consumption pieces (9,588 pure freezers, dump from 29 October 2026), the overall picture is the opposite of what you'd expect from a segment dominated by premium brands: 62% of the market (over 12,700 models out of more than 20,500 with a declared value) is still manual defrost, against 33% automatic. Bosch on its own reverses that ratio: out of 139 pure freezers in its range, 90% are NoFrost and only 10%, mostly small built-in compartments under 100 litres, remain manual. Anyone still defrosting a freezer today is more likely doing it on a chest model or a budget upright than on a high-end one.
How often to defrost a manual freezer
No manufacturer, Bosch included, gives a fixed schedule: Bosch's own support page on defrosting doesn't specify a frequency. Electrolux, which unlike Bosch still sells many non-NoFrost models, is more precise: "if your appliance isn't equipped with No Frost technology, it should generally be defrosted every 3-6 months, or when the ice layer reaches a thickness of about 5 mm" (3-5 mm for pure freezers). The reason isn't cosmetic: built-up ice insulates the walls, the compressor has to work harder to hold the set temperature, and consumption rises, the same principle that links litres and energy class to the yearly electricity cost in our articles on freezer consumption.
How to defrost an upright freezer
For a free-standing upright freezer, Electrolux describes this sequence:
About 12 hours beforehand, lower the temperature to the minimum: food stays cold longer during the operation.
Switch off the appliance and unplug it.
Remove all the food and store it somewhere cool, wrapped in blankets or several layers of newspaper.
Leave the door open. If there's a drain plug, remove it and collect the water in a container.
Place a bowl of warm, not boiling, water inside the compartment to speed up melting, and only pull off ice chunks once they separate on their own.
Once everything has melted, dry the interior thoroughly, refit the drain plug and switch back on.
Set the thermostat to the coldest level for at least three hours before putting food back. It generally takes 6 to 12 hours for the appliance to return to the set temperature.
Bosch, for its own manual models (the few left, mostly built-in compartments), suggests a slightly different trick to shorten the wait: not a bowl inside the compartment, but "trivets with two containers of hot water on top" placed inside, with the water drain open and a bowl underneath to catch it. Afterwards, a sponge is enough to dry the bottom of the compartment before closing the drain again.
How to defrost a chest freezer
The chest format, covered in our comparison with the upright, changes only the working posture, not the logic:
Switch off and unplug.
Remove food, baskets and accessories.
Remove the drain plug if fitted, checking the manual for model-specific instructions.
Leave the lid open and let the ice melt naturally.
Place towels inside and around the chest: there's no vertical door to channel the water to one spot, so it needs absorbing as it goes.
Clean and dry thoroughly, refit baskets and accessories, close and switch back on.
Restart takes the same time as the upright, 6 to 12 hours, longer than the 4-6 hours of a combined fridge-freezer, which has a much smaller volume of air to cool back down.
What never to do while defrosting
On this point Bosch and Electrolux's safety instructions match almost word for word, and it's not a minor detail: the refrigerant circuit of a modern freezer uses flammable gases, and the Bosch manual explains the ban in exactly those terms, risk of explosion.
No sharp objects. Never use knives, screwdrivers or blades to chip away ice: they can puncture the refrigerant circuit. If food is stuck, the Bosch manual recommends freeing it "with a blunt object, such as the handle of a wooden spoon".
No unapproved heat sources. Heaters, hair dryers, steam cleaners or pressure washers are banned "unless expressly approved by the manufacturer": warm water in a bowl or container, never touching the walls directly, remains the only method every manufacturer endorses to speed things up.
Don't refreeze what's already thawed. The Bosch manual is clear: don't refreeze partially or fully thawed food, because bacteria can multiply; only refreeze after cooking it.
Dry hands on frozen food. Wet skin can stick to cold surfaces.
How to clean a freezer, NoFrost included
NoFrost skips the defrosting, not the cleaning: the same Bosch manual says so explicitly, "if the fridge/freezer stays empty for a long period, switch off the appliance, defrost it, clean it, and leave the door open to prevent mould forming". For routine cleaning, Bosch's guide recommends a warm water and baking soda solution or a pH-neutral detergent, never degreasers or harsh products, which "can leave residue" that comes into contact with food. Drain channels are cleaned with a cotton swab or toothbrush, door seals with a damp cloth, paying attention to the folds. Baskets and shelves should be hand-washed: in a dishwasher they can warp or discolour. In case of mould, Bosch and Electrolux agree on the same precaution, wear protective gloves and, if needed, a mask before handling it.
| Format | Manual defrosting | Wait before restocking food |
|---|---|---|
| NoFrost (upright or built-in) | Not required, periodic cleaning only | None |
| Manual upright | Every 3-6 months or at 3-5 mm of ice | 6-12 hours |
| Manual chest | Every 3-6 months or at 3-5 mm of ice | 6-12 hours |
| Combined fridge-freezer | Every 3-6 months or at 5 mm of ice | 4-6 hours |
PortosEunostos tips
Before buying a spare part or calling a technician for a freezer that "isn't cooling properly", check the ice layer on the walls: above 5 mm, in most cases the problem fixes itself with a defrost, not a repair. If you're shopping for a new freezer and want to skip this chore entirely, check the spec sheet for the word NoFrost before you look at the price: as our Bosch versus Siemens comparison shows, NoFrost is no longer an expensive feature reserved for flagship models.
Sources
Electrolux, Defrosting the fridge/freezer (Italian support page)
Bosch GIN81VEE0 user manual, chapters on Safety, Defrosting, Cleaning and care
EPREL registry of pure freezers (dump from 29/10/2026), NoFrost vs manual share, overall market vs Bosch