Frost free fridge frosting up

[stolagt]

I have an AEG Santo 72358KA fridge, installed just under 2 years ago. I noticed a few weeks ago that there was a build up of frost inside the fridge. I called AEG for advice and they suggested I check that the drain hole was not blocked. This I did and it was clear. I changed the carbon filter, defrosetd the fridge and the frost has come back. Has anyone any idea what might be causing this and how it can be fixed without the £65 callout charge>

 

[r.bartlett]

It could be a few things-

1 Door not closing properly
2 Defrost timeclock
3 defrost heater
4 Defrost termination stat

Cheers

Richard

 

[JohnD]

...or thermostat too cold so the ice never melts.

Is it one with a fan?

 

[stolagt]

The fridge has a fan and the temperature readout shows a steady 5 degrees. It's less than 2 years old so I'd be surprised if door seals had gone, and I would have hoped that being made by AEG it would have components that would not give up the ghost so quickly!

 

[JohnD]

unplug it for a while to let any ice in the drain tubes clear.

 

[stolagt]

I did try defrosting it a couple of weeks ago and left it switched off for the best part of a day. As far as I am aware, all the ice had melted, although I couldn't really tell for sure because there is only so much you can actually see. We put a thermometer into the fridge today, and although the digital readout on the outside was showing 5 degrees, the temperature on the top shelf was nearer 10 degrees. We dropped the thermostat down to 2 degrees, the temp on the top shelf went down to about 8, although at the bottom of the fridge it is now showing 4 degrees but the digital readout shows 2. I imagine that the temperature in the fridge will be variable in different parts, but 10 degrees seems very high even accounting for differences. What should the optimum temperature be at the top/bottom of the fridge? Could it be that the thermostat has packed up? Should this be happening to an AEG fridge that is only just 2 years old?

 

[JohnD]

if you pull it out and look round the back I expect you will see a plastic dish on top of the motor. Defrost water runs down a tube into this dish, and the heat from the motor evaporates it. You will know there is no blockage when the tube drips freely until all the ice is melted.

You can sponge out the dish as well and inspect the tube as they sometimes bock with dust, mould or bits of food. If blocked, the water in the tube tends to freeze solid preventing the frostfree from working.

When you defrosted it, did you take out all the food, and leave the fridge door open (and give the inside a wash down)?

p.s. the inside temperature should be about 6 deg C.

Frost free freezers and fridges with fans are relatively prone to blockage and faults as they have more to go wrong that simple ones.

 

[TicklyT]

If the door is twisted or warped (or maybe heavily loaded with milk bottles etc.) the door seal may leak.

You could check the door seal will grip a slip of paper all the way round. If it doesn't, the door seal is suspect.

Some door hinges can be adjusted so the door seal meets the case properly.

I have seen a frost free fridge ice up when one member of the household used to leave the fridge door open when he made his sandwiches in the morning to save turning the kitchen light on

 

[Steve]

I have seen a frost free fridge ice up when one member of the household used to leave the fridge door open when he made his sandwiches in the morning to save turning the kitchen light on

Reminds me of the time I came into the shop to find someone had left a glass display freezer door about 4 inches ajar overnight (it had caught on a stick-out magnetic sign that sticks between the doors). Everything inside was covered in very soft snowy ice. Still frozen though, reading -26!!

 

[stolagt]

Thanks for your replies.
I defrosted the fridge again, leaving it with the door open for almost 24 hours. The drain was working as the container at the back was full and overflowing all over the floor! I then tested the drain again to make sure nothing was stuck in it and the water flowed freely. I tried the slip of paper, but it was a bit difficult as the fascia across the top of the fridge made it difficult to get anything smaller than a sheet of A4 into the door seal. It pulled out quite easily, and when I tried to do the same with the freezer that is bolted to the fridge (it's a side by side model) it came out easily as well, yet I have no probelms with the freezer icing up. We took off all the panels covering the cooling fins inside the fridge but couldn't see anything untoward.
The fan seems to be working OK. The only thing we can think of is that the thermostat is faulty and so causing the compressor to work overtime as it is not registering that the temperature is low enough. Would an engineer be able to do a diagnostic test to identify any faulty component or is he likely to replace a part and see if that works, then move onto the next possibility? I don't want to be forking out a small fortune unnecessarily

 

[Chris_Sav]

Unlikely after all these years that the O.P. will read this but thanks to them anyway!

I have the same fridge Santo 72358 KA3 which I found was terribly iced up. Reading this helped, but mine was so bad I could not get the back panels off as they were locked in the ice. Had to melt it with a hair dryer before the simple job of taking the covers off the cooling fins could take place.

Door seal OK but temp was set low at 3 degrees so might have prevented the ice from melting, raised to 5 and chilling now, hope it's OK

 

[foxhole]

Fan should keep temp fairly even throughout unless it’s seized or blocked by ice , there is a tell tale rattle as you open the door if the fans obstructed ( fan stops when door is opened).

 

[Chris_Sav]

Thanks for the advice, fan is clear on ours which actually appears to be a S75578KG3 from the January 2009 delivery note, just the handbook is 72358. I cannot check due to recent hip replacement so cannot drag the beast out from the wall.

All of the area under the cooling fins covers was a solid block of ice right the way up to the join between the fan compartments. We spotted it due to ice growing on the outside!! of the cooling fin covers. We got half a washing up bowl of water from the volume of ice! Must have been like it for a long time!

All the other checks produced nothing apart from we were running it on 3 degrees, have increased that to 5 degrees and it has settled overnight.

Even if it's terminal, cannot grumble at eleven years. Will monitor closely after Xmas, strange its predecessor failed inconveniently at Xmas as well! too much turkey on board.

 

[JohnD]

sometimes the ducts get choked because the defrost heaters or control circuit have failed. This is not economically repairable but worth a manual defrost once, then wait to see how long it happens again and if you can tolerate it while you save up for a new one.

Sometimes the ice blockage occurs because the door has been left open or something, and, once blocked, it just gets worse. A manual defrost will sort that.

Get an extra thermometer so you will spot if the temps go wrong in future.

But you do have to allow quite a long time for the melt, and if you stop defrosting before all the ice has gone from the dusts, you've wasted your time.

I wish I'd known that before getting my old mum a new FF and paying to have the old one taken away.

 

[Chris_Sav]

Thanks, we used a hair dryer up behind the panels to aid getting them off, all cooling fins warm too the touch before reassembly.

Be an easy job next time as I'll check before the panels get locked into place with ice.