Liebherr CUN 3031 not cooling

[JamboChris]

Hi,

I have a Liebherr CUN 3031 fridge freezer and the freezer part is not keeping a constant temperature. It varies between -20 and -4. It has been fully defrosted for a day and this has not made any difference.

The service number is 0902988-06.

The fridge part works ok but there is what looks like a rust mark running down the back wall on the right hand side. It looks like a dirty water mark running down when the frost on the back wall of the fridge defrosts. Any coincidence ?

I am quite handy with a meter so any guidance on where to look for faulty sensors etc would be appreciated. 🙂

Thanks,
Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

hello chris, is the fridge ok? if so, i’d be looking at if the fan in the freezer is working or not.
if the fridge is ok, then it’s not a system fault, more likely something on the periphery.
the freezer compartment relies on the fan circulating the cold air.
fan faults themselves, whilst they do occur are quite rare and it’s likely that something is impeding the fan or the fan isn’t getting an impulse to run.
hope this helps.

cheers.

[JamboChris]

Re: Liebherr CUN 3031 not cooling

Hi,
thanks for the reply.
The fridge seems to be ok, it does vary between 4 and 8 degrees though. Is that normal?
The fan seems to be running normally as well.
Any more ideas? Your input is appreciated.

Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

You sure the fan’s running ok? It turns off when you open the freezer door.
The fact that the fridge is ok rules out a refrigeration system fault and so your problem must lie inside the freezer compartment.

[JamboChris]

Re: Liebherr CUN 3031 not cooling

I can hear the fan running and it stops when the freezer door is opened. Is it operated by a magnet on the door?
I’ll get a more accurate thermometer and monitor the temperatures of both fridge and freezer the next few days.
How much should the temperatures vary? Is between 4 and 8 degrees normal variations for a fridge?

Thanks again,
Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

hello chris, what you should be concerned with when measuring the temperature of a fridge is the core temperature of the things inside and not just the air temperature, which is what most people take.
also, keep in mind that within the cabinet, there will be a disparity of temperature from the front to the back of the appliance and from the top to the bottom.
if there’s a fan on your model, then that should help keep the temperature fairly even inside.
put a glass of water in the middle of the cabinet and put your thermometer inside the water.
over a couple of hours, the water will assume the temperature that you need to be measuring.
obviously with the door opening and closing and with cold air being heavier than warm air, then just measuring the air temperature will give you a greater fluctuation.
the fan in the freezer is controlled by a magnet which interacts with a reed switch, when the door is opened or closed.

cheers.

[JamboChris]

Re: Liebherr CUN 3031 not cooling

Ok, understood.
Thanks,
Chris

[JamboChris]

Re: Liebherr CUN 3031 not cooling

Hi ELDAR59,
I’ve measured the core temperature of the fridge using a glass of water over the last 24 hours. It’s varied between 3.2 and 5.4 so pretty steady. (There is no fan in the fridge)
I put a small plastic cup of water in the freezer and put a probe in it. The coldest the ice has got is -13 and this morning when I got up it was -8.2. It has slowly dropped back down to -9.5.
I am waiting for a magnet to come from ebay to test the fan with the door open. I’m not sure how often the fan should be running but I can hear it. Sometimes it sounds steady and other times it sounds as if it is ‘pulsing’ ie 5 seconds on, momentarily stops and 5 seconds on etc.
Help!! 🙂

Thanks,
Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

Hello chris, from what you’ve told me re the pulsing, your problem will be with the small pcb that’s housed at the back of the fridge, by the compressor.
Not sure of the part number because I can’t access tech info right now.

Cheers.

[JamboChris]

Re: Liebherr CUN 3031 not cooling

Thanks ELDAR59,

A part number would be appreciated when you can. Is it easy to change? Any idea on the cost?
The feezer has been steady at -15 +/- 1 degree all day.

Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

Chris, if you look behind the fridge, you’ll see the white box holding the pcb by the compressor.
You’ll just need a T15 torx bit to open the box. I’ll come back to you with a part number, unless someone on here has it to hand?

Cheers.

[JamboChris]

Re: Liebherr CUN 3031 not cooling

Hi ELDAR59,

There is no rush, I’ll be leaving early in the morning for a week, so no more freezer dreams for a while.
Thanks again for your help, night night.

Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

hello chris, part number is 6113868. this should do the trick.

[JamboChris]

Re: Liebherr CUN 3031 not cooling

Hi ELDAR59,

Just off the phone to Liebherr and they say they will not sell the PCB to me. They will only sell to electrical companies/engineers.
Any suggestions of how to get it?

thanks,
Chris

[ELDAR59]

Re: Liebherr CUN 3031 not cooling

Have you tried this site?
Not that I’m aware of any terms or conditions that may prevail, but it’s worth a try.

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