Liebherr fridge “forgets” to start cooling

[poce]

Hi,
I’ve got a 6 years old Liebherr CNES4056, which has worked wonderfully well until a couple of months ago.
I am now facing this problem:
Often, particularly during the night, the temperature inside the fridge is not kept at the set level (5C in my case), but it rises up to 12C-13C.
If I press the Super Cool function on the LCD panel, the temperature drops fairly quickly down to 2C, so the compressor seems to work fine and it doesn’t look like there is a lack of gas in the circuit.
I’m not a professional, but I decided to extract the PCB from the back and I re-seated the all the sockets, hoping that the problem was caused by a faulty contact. Unfortunately this didn’t fix the issue, so the prime suspect in my opinion is the temperature sensor in the fridge that doesn’t detect the temperature rising and doesn’t trigger the cooling.
Please note that:
– The problem is not always happening (the fridge can work fine for several hours keeping the temp to 5C)
– It seems that the issue is more common at night, that is when the door is not opened for many hours
– The Freezer doesn’t have any problem and is keeping the temperature steady at -18C
I looked in the forum and I found a similar issue, but my fridge behaves differently.
Did anybody have a similar experience or is there any advice/suggestion that you can give me?
Many thanks and regards,

Davide

[kwatt]

Re: Liebherr fridge "forgets" to start cooling

It’ll be one of the sensors probably and if you can give me the service number I or others can look it up and see what’s fitted and where.

K.

[poce]

Re: Liebherr fridge "forgets" to start cooling

Hi kwatt, thanks for the quick reply.
the service number of the fridge is 9989186-01
I’m keen on trying to replace it myself, unless it’s a very difficult job.
In case, do you know if there is any service manual that I can look at?
I have seen where the cable runs along the back of the fridge, but I am unsure about how to extract the sensor from the fridge itself.
Many thanks again,

Davide

[kwatt]

Re: Liebherr fridge "forgets" to start cooling

There are two sensors in the fridge and one in the freezer shown as 190, 195 and 200 on the attached blowout.

Info on thermistors here:

http://www.ukwhitegoods.co.uk/help/fix- … hermistors

Fault code on that mode here:

http://www.ukwhitegoods.co.uk/help/faul … 2061506660

On service manuals, you won’t get one here’s the scoop on that:

http://www.ukwhitegoods.co.uk/help/fix- … ce-manuals

But what you need to do really is suss out what thermistor is not working then replace it.

K.

[poce]

Re: Liebherr fridge "forgets" to start cooling

Ok, thanks for all the info.
I read the one about the manual and I completely agree.
I am an IT manager, so not really very familiar with home appliances, but I like to understand how things work, that’s why I wanted to give it a try.
And of course there is the cost aspect.
I know that there are plenty of honest technicians, electricians etc. out there, but there are also a lot of dishonest ones, which would come, charge 100 just for the visit, and another 300 or more claiming that both the thermistor and the PCB were gone and there was nothing else to do but replace them, and I won’t have arguments against that.
I am happy to pay a fair amount for a good and honest service, but when I called Liebherr, the first thing that I was told was that they can contact an authorised support engineer that will come and charge 150 (if I remember correctly) for the visit. Than there is the work and parts…
I would have liked to say that in my opinion a fridge that cost around £1000 shouldn’t be faulty in 6 years, but maybe i have just been unlucky.
Anyway, enough with the rant.

Coming back to your suggestions, they make a lot of sense, but the problem is that I don’t get any error message on the panel, so the “brain” of the fridge seems to think that everything works perfectly well.
So the only option for me to check which thermistor is the faulty one, will be to extract and test them both.
I’ll try to do it this weekend, and if I screw up the fridge, well, I’ll need a new one 🙂
Many thanks for the links the help so far.
poce

[poce]

Re: Liebherr fridge "forgets" to start cooling

Hi kwatt,
finally I managed to do some further tests on my fridge to try to figure out if it’s the temperature sensor or a faulty PCB that prevents the fridge to keep the temperature at the correct level.
I extracted the sensor (I found only one in the fridge compartment, unless the second one is inside the internal fan, which I didn’t open) and I kept it near a hot cup of water. I noticed that the fridge digital display wasn’t changing if not every 3-4 minutes and always increasing the sensed temperature by 1 degree at a time, while the sensor was surely at 20C or so.
So I switched off the fridge, left it off for few minutes and then switched it back on. At the start, display would report the correct temperature (around 20C) and the compressor would start.
This makes me think that the problem might actually be the PCB and not the sensor.
Have you got any suggestion?
If it is the PCB, how can I get the right one and do you know how much it could cost roughly?
The service number of the fridge is 9989186-01 and the model is Liebherr CNES 4056 bought in 2009.

Many thanks,

poce

[Author]

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