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Techdesk, Field Service Engineer
Category: UK Appliance
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Experience:  Whitegoods engineer working for a multibranded national company in the UK.
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Hello Fred, I hope you dont mind me asking, but I saw you

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Hello Fred, I hope you don't mind me asking, but I saw you had given a very helpful reply resolving an issue with a Beko Fridge Freezer CDA543FW two years ago, and I thought you might have a hunch what's wrong with mine. You said there is just one thermostat for both compartments. I was searching to work out if there were two, because I had a feeling that the fridge was switching on and off with the knob inside, but the freezer compartment below was apparently always on, the fan running and the temperature down to -24 C before I switched it off. I noticed something was wrong when the fridge was too cold and ice was forming in the bottom of the vegetable chiller, right above the freezer. However, the upper part of the back of the fridge was also frosted up, so I removed the ice, and I then thought it was defrosting ok, sometimes drops of water, sometimes ice. Maybe this was just with warming the whole thing up when I was taking it apart, and perhaps the thermostat has gone after all. I hope so - I can replace it easily for under a tenner. If not (I could try to check again if the fridge rear panel is really switching on and off), what else might cause the freezer to be on constantly? Many thanks in advance if you can help. At the moment it's plugged in to a mains timer to keep the fridge somewhere near the right temperature. Incidentally, I've checked at Beko and it's not one of those requiring a recall.


The fridge thermostat controls both compartments.


If your freezer was down to -24 then the thermostat wasn't cutting out to stop the compressor.


It can be a fault with the thermostat or, it can be a fatal fault where the sensor bulb at the end of the thermostat capillary has come away from it's fixing to the evaporator.

This is foamed in so cannot be repaired.


Basically, the part that the thermostat phial goes down into should be held against the evaporator, where it senses the temperature.

When this pops away from the evaporator, the phial isn't in contact and can't sense the temperature.


The only way to tell is to change the thermostat.


If it still gets too cold and freezes in the fridge, it's the fatal fault I'm afraid.


Try a new thermostat, it's a fairly inexpensive gamble to try it.


Check it out, let me know how it goes.

Hope this helps


Customer: replied 3 years ago.

Thanks Fred. I'm thinking I must have got the wrong end of the stick regarding the thermostat. I thought it was the PCB directly attached to the temperature control knob. Is that it? Your answer suggests that it's down behind the freezer, unless I'm wrong about what the "evaporator" is - I was assuming this is the reservoir for the defrosting run-off water on top of the compressor (big black thing!). I obviously need to get the right thing. Is it this? If not, could you give me any direction to find it (on the machine and/or online to buy)?


I haven't been able to find anything else that looks easy to replace. Cheers.


OK, you have the later version of the machine.

Early versions had a thermostat with a capillary tube and phial.


You have an electronic thermostat.

This is in the fridge section.


The freezer still controlled by the fridge though.


I'm just going to have my tea, then, I'll look up your machine and see what's what and what part is most likely to have caused the problem.


Since you defrosted, has it been ok?




Customer: replied 3 years ago.

Thanks. No, after I defrosted (and there was hardly any ice in anywhere), I put it back on after a few hours and it just went straight down to -24 C. The full model number is XXXXX (sorry, I only found this after my first post). It was bought 2011, and the serial no. is XXXXXXXXXX From what you say, it sounds like the part I linked to must be it, as that is listed as the correct "thermostat" for that model. Your info also explains why I found other "thermostats" that look entirely different - I guess for the earlier version. Look forward to your post, enjoy your tea.


OK, thanks for that.


It gets even better, you're on a much later machine.

Using the full model number I've got the information on your appliance now.


The sensors for your appliance are in the freezer.

The temperature in there controls the fridge.


The part you linked me to is simply a potentiometer that adjusts the temperature inside the appliance.

There is a main control board and it should be mounted in a box on the rear of the appliance.


It's possible that either of the boards could cause the fault but it's much more likely to be the sensors.

Particularly, the air sensor.


I don't think Beko thought these would ever need replacing but, there is a technical bulleting giving instructions (and part numbers of the sensors) on how to replace them.


Click here for the information sheet.


I'd be more inclined to say that the air sensor was the cause of the problem.

Check it out, see how it goes and get back to me if you need more help.


For parts, I'd suggest checking

Use the part number from the information sheet and put it in the search box. It should find the parts for you.


Hope this helps


Customer: replied 3 years ago.

Much appreciated, Fred. I've been able to remove the back plate in front of this assembly, which I didn't want to pull before, but it just waggles out. So I'll get the air sensor and replace it and see whether that fixes it. I'll let you know. You don't think it's likely to be the potentiometer PCB, or if there's a quick way to test that, before I go ahead (including with a multi-meter)? Many thanks. You've done a lot - I should really have paid the higher amount, but I've not been on this site before.


It's not normally the potentiometer but, there's a small chance it could be.


Roughly, the potentiometer, main board or sensor can all cause the problem.

The most common cause is the sensor.


Don't worry about the amount, it's fine.


I can only tell you, from previous experience on these appliances, that I've replaced a lot more sensors than I have replaced potentiometers.


If you have a multimeter, measure the resistance of your one, as you turn it, it should change resistance.

If it does, it's more likely the sensor, if it doesn't change, it's the potentiometer.



Customer: replied 3 years ago.

Thanks Fred. I'll order one and be in touch when I've fitted it, unless the pot doesn't show any change.


No problem.

Customer: replied 3 years ago.

Hi Fred, a funny thing happened last night after I found the sensors, replaced the back panel and drawers and plugged it in again - it started working, or rather, not working constantly. I left it overnight with my max-min thermometer in and it was -18 degrees in the morning, having gone from -15 to -20. I've tried turning the temperature knob down and after a minute or so it switches off, and up again it switches on. So I'm thinking it might be that while I had that panel off I tried pulling and wriggling the connectors (I think one goes to the other sensor and one to the fan), and maybe there was a dodgy connection. If this gives you an important idea about what else might be wrong, please let me know (I've now got to live with the slight worry that it might do it again, while we're away on holiday or something) - otherwise I guess we're done. You've been a great help despite the advice not having to be put into effect, and I've learned a lot. Thanks. John


Fingers crossed it lasts.


If it doesn't, I'd still suggest the sensors be changed first.


Good luck with the appliance.



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Customer: replied 3 years ago.

Hello again, Fred,


Things have taken a turn for the worse here. The fridge freezer started diving below -25C again yesterday and didn't respond to turning the temperature down - a return of the same problem, it seems. I thought I would check with Beko that the air sensor was the correct one for the model (number taken from the pdf you linked to, and a couple found online) - I sent them the fridge model and serial number. I had already asked and also whether the method was to cut it and re-wire the new one in, and they declined to advise me, probably for health and safety reasons on the fitting, but they also failed to assure me it was the right part. This time I [email protected] via the main website. I've just got the reply "The CDA543FW-2 does not have an air sensor." from a Will Mushamba, Spares Adminstration Team.


I'm not sure what to do next, other than phone a local engineer to come and fix it, or phone the beko number in the user manual. I wonder, however, if you might check for me, please. Your initial advice was mistaken, if you remember, regarding the "thermostat with a capillary tube and phial", which didn't seem to square with what I was thinking was the "thermostat", behind the temperature control knob, which I identified by its markings and appearance and found online, described sometimes as a thermostat. You decided I had a later model and that was when you sent the pdf. I would have rated your service as excellent, but for that change of mind. Now I'm not sure what to think.


I wouldn't be surprised, however, if Beko have it wrong. Certainly the pdf looks somewhat like what I found in the back of the freezer, although it seemed to be on the opposite side of the fan in mine.


It is also playing on my mind whether the failing part (if it is the air sensor) would be likely to go intermittently, or if the last week of perfect behaviour indicates something else - hence I'm starting to think fixing it myself was maybe false economy and to get someone in with proper equipment to check it over.


If you are able to put any more time into this and need the full email I got from beko (not that there's much more), please let me know - I guess I can forward it to your latest. I've copied the serial number I sent them from that email and now send it again for you to check (as it's turned to Xs in the web page): XXXXXXXXXX


Kind regards



No sensors are shown in the diagrams.

The only place they are shown is in the technical bulletin I posted, this is listed under your machine.


Beko are a nightmare I'm afraid.


The initial advice was given on the model number originally posted.

Unfortunately, you had a later version (shown by the -2 after the model number), hence the reason I had to go back and look at different technical information.


Sorry, but you would need to check, using the technical bulletin, and see what's actually on your machine.



Customer: replied 3 years ago.

OK, thanks Fred. I'll have to get an engineer in. I don't really know what I'm looking at, and Beko don't think it has the air sensor listed on the technical bulletin. I don't have any diagrams. You say there aren't any sensors listed on the diagrams. Nobody on the planet seems to know what parts the thing is supposed to have. I give up! Not your fault, of course, and yes, I didn't quote the -2 part of the model originally.


Thanks again, all the best



If you look back through the posts you'll find the links to the diagrams on sensor replacement.

If it's the exploded view you mean, sorry, there's no sensors shown on them.


If there's no air sensor then the machine couldn't know what temperature it's achieving.

However, knowing Beko, you may have the air sensor in the fridge and defrost sensor in the freezer.

I also think, most people at Beko don't have a clue.


How many sensors did you find in the freezer?



Customer: replied 3 years ago.

Sorry, I thought you meant technical drawings. Yes, I found the replacement pdf before. I'm pretty sure you're right about Beko, and if that pdf applies to my unit, they're obviously wrong.


I think I found two sensors, as you suggested there would be. One is as the pdf shows and as you suggested, wired in through a seal - hence it would be likely to be as per the pics here:


and here


(I sent these links to Beko!)


The other sensor, if that's what it was, was a similar looking cylindrical thing, but it was plugged in to the socket bank. Another plug went to the fan.


I'm sorry - I'll have another look - it's full of food and running on the mains timer again just now. I could take a photo and send it - either attached to your email or I have an online image host I could link to.


But it really wasn't far off the photos in the pdf, although reversed, oddly - on the other side of the fan. Actually, I never tested the pot, since the fridge started working again. I'll start there when I get time - test the potentiometer and see what it's doing. Then, if that's ok and you're fairly sure that pdf applies, I'll risk the tenner for a new air sensor (that it doesn't have, lol).


And you'll deserve an upgrade to excellent. :-)


I'll enjoy emailing Beko to tell them I've replaced the part they say it doesn't have, too.





Nice one.

Have a look again at the sensors and if they look right, I'd risk the £10.


The alternative is a new machine.


Good luck with it.


Customer: replied 3 years ago.

Hi Fred, sorry to bother you again. I'm confused about these sensors. I'm going to try your advice of changing the air sensor. I wondered if you could just confirm that I'm about to get the right thing, and how to fit the business end. This seems to be one


But it also mentions the evaporator sensor, with a "large insulator". It seems to suggest that this is wired in like the air sensor, but the insulator is heat shrunk. The general instructions say:


"Put the insulators to connecting points and shrink with warm air" (I presume this means the electrical insulation heat shrink) ...

"For evaporator sensors, put the big insulator to all connecting surface and shrink with warm air" (No idea what this is - I don't see anything similar in mine, maybe hasn't got one?)


The document you linked to also mentions both sensors. It also gives a "before" and "after", but I'm not sure what's what really.


The only sensor that is wired through the freezer insulation in mine has a cylinder of white plastic at the end of it, cable-tied to the evaporator assembly (evaporator or heater perhaps), and the photos of the air sensor on the websites just shows a black object, and doesn't seem to show what the "large insulator" looks like for the evaporator sensor.


Does the black air sensor fit into the white cyclnder? Is is sealed in? Or how else do I fit the business end of it?


Here's what the inside of my fridge looks like:


Many thanks


I don't have any more information on this.

I'll opt out of the question, see if any one else can help