How do they work?
Frost free fridge freezers are very popular and auto defrosting fridges are a great convenience. In a frost free appliance the cold air is blown round the freezer using a fan. On modern refrigeration the evaporator (which is the plate that gets cold) is hidden behind the plastic wall inside at the back of the food shelves. When working correctly you can usually see small beads of ice randomly scattered on the back wall unless it’s in a defrost cycle when you may see water.
Heater inside
the 
Believe it or not most modern refrigeration has a heating element inside. This heater is used to defrost the appliance automatically. During the defrosting cycle the ice on the back wall melts and runs down the back wall into a channel. It is then directed through a hole out through to the back and runs into the evaporator tray. The evaporator tray is on top of the compressor which gets pretty hot and evaporates this water into the air.
Because the evaporator is behind a back panel the cold air has to be blown around the compartment with a fan motor. The defrost cycle also needs sensors and a timer and combined with several sensors throughout and PCBs to control everything the result is there is a lot more to go wrong than there used to be in old-fashioned conventional fridges. However, they are still fairly reliable.
Common problems with frost free fridge freezers
If the door is left open for too long (especially in humid conditions) the evaporator freezes over and the unit will not keep the food cold. This problem (unlike the older machines) has a greater impact because you can’t see the amount of ice built up around the back of the panel hiding the evaporator.
In many frost free fridges the ice can form all the way round the fan and cause it to run slowly or even seize up. Prior to seizing up the fan may catch on the ice and make a high pitched noise. This will of course result in the fridge or freezer not getting cold. If you hear a strange noise from your frost free fridge freezer which sounds like something is catching on a rotating fan it could be due to ice forming around it.
If it stops working due to ice forming behind the evaporator and round the fan then defrosting the unit manually can fix it but it involves unplugging the unit for at least take 12 hours or so.
You may not see much frost as it would be behind the back wall or behind the fan unit.
You can’t really use a hair dryer on modern units because they may have a thermal fuse which protects the defrost cycle.
Also, even just getting to the evaporator to defrost it can be a mammoth task especially with some of the new American-style fridges.
If a fault re-occurs later it could be due to faulty sensor but if the fault was only due to the door been left open for a few hours accidentally then a total defrost could work. This demonstrates the type of problem many people have when confronted with these larger bulky hoses with specific fitting instructions as described in the main article on the left.
Water or sheet of ice inside fridge
If your fridge has two sloping channels at the back wall and a hole in the middle this is designed to channel the water created on the defrost cycle through to the back of the unit where it runs onto an evaporator tray which can get blocked. More details on this here- Ice or water in base of fridge or freezer.
Whilst we are on with American style frost free fridge freezers, because the doors are so big and can store so much, the opportunity to overload them is greater. This too causes warm air to pass into the unit and frost it up.
Remember a frost free unit will not cope with too much ice on the evaporator so greater care must be taken to use it correctly and check the door seals regularly.
Summary
It’s common knowledge that most people rarely read the instruction book supplied with their new appliance. This is particularly true with something like a fridge or freezer. It’s easy to imagine most people thinking you only need to plug it in, leave it plugged in, and fill it with food – what’s to know?
I would advise anyone with a modern refrigeration appliance, especially the American-style fridge freezers, to carefully read the instruction book. Modern frost-free refrigeration units work very differently to a conventional fridge or freezer. It’s even important to learn how to stack them properly otherwise you can prevent the air from circulating inside and cause warm spots.
You would be surprised at what you can learn from reading the instruction book of an appliance you already know how to use. Many User instruction manuals can be downloaded here.The page concentrates on washing machine manuals but links to appliance manufacturer sites where users such manuals for fridges, freezers and other appliances should also be available.
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Hi, very helpful article. This may sound a silly question, but how can you tell if you have a frost free fridge, the fridge part of my fridge/freezer doesn’t work but the freezer part works fine, i wonder if it needs defrosting.
Thanks
Anonymous: Frost free only applies to the freezer as fridges don’t generate any frost. If your fridge freezer is frost free and the fridge isn’t getting cold there could be a blockage stopping the cold air being blown into the fridge compartment. This could be ice so a 24 hour defrost could work. However, if the fault returns it will need looking at by an engineer.
(Appliance repair companies)
I have a zanussi fridge freezer which works fine but every so often it makes a terrible banging noise not quite as bad but similar to a compressor kicking in. Is this normal?
A similar question was asked by ernie when he said his made a noise like a jack hammer – I replied underneath. Hope it helps
Dear Washerhelp
Thanks for such an informative blog. I have gone through most of the problems discussed above.
My problem is a bit different. We are planning to replace our existing refrigerator (which is not frost free and accumulates frost in freezer compartment.) I am currently in a city where continued suppy of electricity is a problem. The power normally goes off one hour each thrice a day. On some hot days, or due to grid power failure the shut down could be prolonged may be 6 to 8 hours. Now the issue is, with a freezer having forsting mechanism, there is lot of ice inside the freezer compartment, which can keep the frozen food intact for a longer period. I was wondering what would happen if there is no ice in the freezer compartment (if I buy fros-free fridge), and power goes off. I presume it would certainly impact the food quality and might spoil it or render it unconsumable.
what do you recommend in this scenario, shall we go for frost free or for old frost type?
thanks in advance
AMBAR
Hi Washerhelp
Many thanks for making the effort to put all of this information up. I know you’ve answered this problem before, but I’ve got a slight variation to ask:
I have one of those fridge / freezers where the fridge is cooled by pumping in cold air from the freezer compartment. Sadly, every few months, the fridge bit seems to stop working – I’m guessing because the air conduit gets blocked by ice. We empty both compartments (bye-bye lovely food) and switch it off and leave the doors open for a few days, and then all is ok again (for a few months). In this instance I’m a bit fed up and don’t want to lose all my food again, and wondered if there’s likely to be any way I can get in there manually, remove the ice blockage myself, and get the unit back up and running before the food has had time to go off.
Also, do you have any other tips as to things we might be able to do / not do to stop this happening in future (fyi we’ve had engineers out, but they just recommend the defrost solution!)
Thanks again for your help,
Stephen
Hi Washerhelp
further to the above comment, I’ve noticed something that may help diagnose the problem (if indeed it’s in any way different to the problems already mentioned on this board): when the f/f malfunctions in this way, it also seems to misread the temperature of the fridge section. It’s currently reading 2-3 deg Celsius, but the temperature in the fridge compartment is very clearly not that low (more like 18 – it’s warmer in there than it is in the room!)
Stephen
i have been trying to establish the difference between fridgefreezers that have both frost free (freezer) & auto defrost (fridge), & those that are advertised simply as frost free. In spite of the huge help your site has been, I’m still confused: on the one hand I’ve been told that ALL modern fridgefreezers have auto defrost, but if so why do manufacturers differentiate – advertising some models as frost free and auto defrost, & others simply as frost free? Beko has both types & so do other makers. This ambiguity along with other constraints like having small kitchen means I’ve spent 6 months without a fridgefreezer, trying to find right one. OK, bit obsessive!
I had a lovely one but left it behind, not expensive but never any trouble; it’s quite scary reading all that can go wrong….but if, like mine did, they work properly they are so much more convenient than those that need defrosting manually. thank you
I have a zanussi frost free fridge freezer which I was expecting to give years of good service but has now broken down. I guess I’ve had it 5 years but that doesn’t seem that long for a good brand. The cold air seems to be circulating to the fridge and there is a humming sound but the usual loud noises that indicate it is working, seem to have stopped – fridge showed sign “too warm” but seemed to be working a little bit but don;t think freezerwas working at all. In first instance I could hear slight “clicks” (and my kitchen lights flickered) when I waited for it to start up but then it wouldn;t kick in as normal. Now I am not sure I can hear anything expect the hum. I left it off overnight and have tried to get a repairman to come today but no-one likes frost free! One person told me to leave it at least 24 hours with doors open in order to ensure it is not iced up behind panel. I am doing that now but none of the 3 people I called, volunteered to come and look at it if this does not solve the problem! And I thought there was a recession and people wanted the business!
Apologies for not replying sooner –
AMBAR: If the power goes off you need to not open the door until power is resumed and the temperature’s gone down again. The fridge is insulated enough to normally maintain temperature for several hours as long as the door isn’t opened though if it’s very hot I’ve no idea how long it would take to defrost. I’m not sure how much impact the ice would have in maintaining a cold temperature with the power off. It’s possible it won’t make much difference but I understand the logic behind assuming it would be better with ice inside so it may be better to keep the old type in your circumstances.
Stephen UK: If you are leaving it unplugged for a couple of days you will be completely clearing the blockage or the ice if the fan is getting encased in ice. If it keeps returning then clearly there’s a fault that needs fixing properly. You need to find a proper fridge repair expert – not ones that just tell you to defrost it. Your fault could be caused by a faulty sensor over freezing, an ill fitting door or one with a worn door seal allowing air to be sucked in which then forms ice around the fan or a blockage or the problem with the defrosting system.
pat, harrogate: Frost free means no frost is generated, but auto defrost means frost is generated and the fridge automatically gets rid of it by defrosting. “Frost Free” shouldn’t need to defrost. Some manufacturers may try to con by saying their appliance is “frost free” because it automatically defrosts but true frost free can only mean that it runs without creating any frost (or ice) in the first place.
maria Modern frost free refrigeration is complex compared to the old fashioned fridges and freezers that just had a compressor and a capillary thermostat. Compared to the old ones they are very complicated and many people who are sent to repair them aren’t really thoroughly up to speed with them. I would try the manufacturer or look for a specialist refrigeration repair company.