Usually because the evaporator coil has iced over and can no longer move heat, and you have roughly 24 hours of stock life with the door kept shut to find out which of six things caused it.
Skai Solutions wrote this after checking what Australian food law actually requires of a freezer, and the answer is that it requires no temperature at all. Below: what the failure costs, how long you really have, the six checks ordered cheapest first, what to do in the first hour, and when to stop repairing.
Start with the stock, because it is the number that decides how fast you act. A 2.4 metre freezer room holding proteins and frozen prep is carrying thousands of dollars of inventory, and a replacement compressor is A$1,000 to A$3,500 on the parts pricing published in the HospitalityHub cool room and freezer room buying guide, updated 24 April 2025. A door seal is A$50 to A$150. A thermostat is A$100 to A$300.
So the arithmetic is nearly always that the stock is worth more than the repair, and the repair is worth more if it happens before the stock thaws than after. The clock is the thing to understand first.
The NSW Food Authority's guidance is that "freezers will generally not defrost and spoil for at least 24 hours if the door has been kept shut", and that frozen foods, "if thawed, should NOT be refrozen and should be kept cold and consumed within 24 hours".
Handle that honestly, because we are not going to present it as something it is not. That page is written for households, by the state food regulator, in the context of a power failure. It is not a business compliance rule. What it gives you is a realistic physical expectation: a closed, full freezer buys you roughly a day, and a half empty one buys you less, because frozen mass is what holds the temperature.
The business obligation sits elsewhere, and it is looser than most operators think. See the next section before you throw anything out.
There is no number. We checked both of the Food Standards Australia New Zealand storage pages on 22 October 2026. The storing food safely guidance, last updated 1 October 2025, contains exactly one frozen food instruction, in FSANZ's own words: "make sure frozen food stays frozen hard". No figure is attached to it. The temperature page, last updated 30 September 2025, does not use the words frozen, freezing, thawing or refreezing at all.
Compare that with the refrigerated side, which is a hard number in the same guidance: "potentially hazardous food must always be at 5C or colder, or 60C or hotter to keep it safe". The Code is specific about your fridge and silent about your freezer.
So the -18C everyone quotes is the operating point freezer equipment is sold against, not a threshold you can be measured on. Suppliers advertise freezer rooms at -18C to -25C, which is where the figure comes from. The test an inspector can actually apply is whether the food is frozen hard. New Zealand venues work to a food control plan under the Food Act 2014 and we have not verified the position there, so do not read this as applying across the Tasman.
Practically, this cuts both ways. A freezer sitting at -12C is not automatically a breach, but food that has gone soft is not frozen hard and is not covered by the frozen exemption either. At that point it is refrigerated food and the 5C rule applies, which is the regime our page on a commercial fridge that stops cooling covers.
A freezer has one failure mode a fridge does not: the defrost circuit. Work the list in this order, because it is ordered by what costs nothing to check.
In this order.
Then it is a service call, and the two decisions worth making deliberately are whether to repair or replace, and what you do with service in the meantime.
On repair against replace, the honest line is the one the running cost makes. A replacement compressor at the top of that range is A$3,500 on a freezer room whose panels and condensing unit might list around A$11,879 new, on the 15 Australian listings we read on 22 October 2026 for our cool room cost page. A A$3,500 repair on a unit that is twelve years old and drawing 25 kilowatt hours a day is usually the wrong call, and a A$300 thermostat on a four year old unit is obviously the right one. The number that decides it is age plus consumption, not the repair quote on its own.
On trading through it, a kitchen running on daily deliveries and no frozen buffer is a kitchen with a much tighter ordering routine for a week. That is an operational problem, not a refrigeration one, and it lands on whoever is answering the phone.
Three things, and the first one costs nothing.
Energy is worth watching too, because a freezer that is working harder is telling you something before it fails. The month a unit's draw climbs is the month to look at it, which is the discipline on our restaurant electricity cost page.
A freezer failure takes your head chef off the floor for half a day. Somebody is on the phone to a refrigeration mechanic, to the supplier about an emergency delivery, and to whoever has freezer space. For that half day nobody is answering the booking calls, and those calls do not come back later.
A Skai Solutions AI phone agent answers every call while your kitchen is dealing with something else, takes the booking into your system, and is live in five days. It does not fix the freezer. It stops the freezer costing you Friday night as well.
Why is my commercial freezer not freezing?
Most often because the evaporator coil inside is iced over, which stops it moving heat so the compressor runs constantly and the box warms up. The ice itself is a symptom: the cause is usually a failed defrost heater, a dead defrost timer, a stuck termination thermostat or a door seal letting warm kitchen air in.
What temperature does a commercial freezer have to be in Australia?
There is no legal figure. Checked on 22 October 2026, the FSANZ storing food safely guidance carries one frozen food instruction, to make sure frozen food stays frozen hard, with no temperature attached, and the temperature page does not mention freezing at all. By contrast the refrigerated rule is a hard 5C or colder. The -18C commonly quoted is the operating point equipment is sold against.
Is -18C a legal requirement for freezers in Australia?
Not on the evidence of the regulator's own pages. Suppliers advertise freezer rooms at -18C to -25C, which is where the number comes from, but the Food Standards Code test is whether food is frozen hard. New Zealand venues work to a food control plan under the Food Act 2014 and the position there is unverified.
How long will a commercial freezer hold its temperature?
The NSW Food Authority's guidance, written for households in a power failure, is that freezers will generally not defrost and spoil for at least 24 hours if the door has been kept shut. A full freezer holds longer than a half empty one because the frozen mass is what holds the temperature. Treat it as a physical expectation, not a compliance rule.
Can you refreeze food that thawed in a broken freezer?
No. The NSW Food Authority's guidance is that frozen foods, if thawed, should not be refrozen, and should be kept cold and consumed within 24 hours. Food that has gone soft is no longer frozen hard, so the 5C refrigerated rule applies to it from that point.
How much does it cost to fix a commercial freezer?
On parts pricing published in an Australian buying guide updated 24 April 2025: door seals A$50 to A$150, thermostats A$100 to A$300, fans and motors A$200 to A$500, and compressors A$1,000 to A$3,500. Labour is on top. The decision between repair and replacement turns on the unit's age and daily consumption rather than the quote alone.
What is the first thing to do when a freezer stops freezing?
Keep the door shut, then take one probe reading between two packs rather than reading the door display, then move the highest value stock into anything still cold. Write down the time you found it and that first reading, because if anything has to be discarded that note is your record.
Why does a freezer ice up inside?
Because warm humid air is getting in and condensing on the coldest surface, which is the evaporator coil. The usual routes are a door seal that no longer seals, a door left open during deliveries, or a defrost cycle that has stopped working. The paper test on the seal takes five seconds and the part is the cheapest on the unit.