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 Washerhelp
Thank you for comments, very helpful.
I have a Prestige PRT 325 FFCS my fridge has packed up I have tried turning off the fridge and leaving the freezer as that is functioning ok but still not cooling. Have seen some terrible comments on this model from another site. Is it worth calling an engineer. Had this one for 3 years.
I have a JOhn Lewis fridge freezer. I’ve been away for the weekend and came back to a fridge that smells a bit. I noticed the fridge temp has gone up to 14! What can I do? The freezer part is fine. I did leave the door open a few times last week!! Please help. Thanks
Frost free fridge freezers are prone to icing up around the fan if the door is left open. This can cause the fan that blows the cold air around the fridge to become encased in ice and stop running. Prior to stopping all together they often make a searing noise as the fan catches on enclosing ice. If the fan is restricted or the fan chamber blocked with ice the fridge can warm up as cold air can no longer circulate.
A remedy to this can sometimes be a complete defrost by removing all food and unplugging the appliance then leaving the door open for at least 24 hours. As the ice is deep in the fridge it will take a long time to defrost properly.
Hello – I have just switched my fridge freezer back on after defrosting it. How long do I have to wait before I can safely put some food in it? Many thanks.
my frost free fridge freezer seems to have puddles water at bottom fridge an ice has now formed at bottom freezer help only 4yrs old expected to have longer.
Louisa: Sorry about the delayed reply. I would say when it’s reached temperature which is normally around -18 degrees on a freezer.
Katie: The hole at the bottom of the back wall is possibly blocked. When defrosting the water from the back wall runs down into two channels and out through the back where it evaporates in a tray on top of the compressor. If this passageway is blocked water will run into the base instead and freeze up.
Greetings Washerhelp – no worries, I understand. Thank you for taking the time to reply. I’m so glad that I have found such an informative website.
Hi, I have a John Lewisfreezer model: JLUCFZ6002 now 5 years old. 2 years ago the drain valve was replaced. Now I appear to have small deposits of frost on the bottom. Tried a 13 hour switch off which resulted in losing my ice cream ( no big deal ) but the problem is still there. Any ideas?
I have had trouble with my frost-free fridge freezer since purchasing it in 2007. The first one had frost on ‘ceiling’ of the freezer and condensation on the outside of appliance. Repairman concluded it was faulty and I was supplied with a new one of same model. This one, which arrived in 2008, also gets frost on the ceiling of freezer and last autumn had terrible noises which I think was fan icing up. I called repair team and was told to switch machine off. This meant had to do a total defrost which took forever, and you can’t leave the machine for more than 5 mins at a time as not designed to be defrosted so nowhere for water to go except floor! therefore need to be on hand to mop up all day) . Repairman arrived and said there was a fault with a hose not being large enough so he cut a ‘v’ in it and sealed something at bottom.
For the first time ever my appliance had no ice on the ceiling for 3 months. But now – it’s back with a vengeance and even icicles have formed! I have done 2 mini defrosts by placing my food in freezer bags for a couple of hours but the frost returns. I never leave the door open and am always checking that it is closed, especially at night when it is a ritual to check it like switching off lights and locking doors. I have no young children either so the door is firmly closed for most of the time and really only opened in evening when I need food for cooking or sometimes in the day when putting frozen shopping away. The seals all look fine and the appliance is properly surrounded by ventilation. Help please! ps. Do frost-free freezers hold loads more water than conventional ones? I think now I will return to purchasing a conventional non frost-free freezer.
Hello,
I had a Beko frost-free fridge freezer deliverd on Saturday. I wasn’t aware that it was frost free (and to be honest, would have not known to check this). The fan comes on every half hour for 10 minutes. I have an open plan lounge / diner and this is quite annoying. It emits a high pitched whistle (and gurgling).
I note from the site that this noise may be normal? I used to have a Zanussi manual defrost. However, this actually made even louder noises (so would have been no good in an open plan room). My parents have a 17 year old fridge freezer, totally and utterly silent (although it’s still working!).
I am trying to ‘live’ with the noise. The fridge and freezer are currently empty, I have simply plugged the unit in (after waiting 6 hours).
Question : is it normal for the fan to come on this regularly and will the noise diminish when the fridge & freezer are full?
I am tempted to ask for a refund and go to back to manual defrost. However, is there any guarantee that this may be totally silent?
Thank you