Liebherr CUN3033 Freezer not cold enough

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  • October 3, 2015 at 12:26 pm #86278
    PClem
    Participant

    Hi,

    I hope somebody can help me with a fault I have on my Liebherr CUN 3033 Fridge Freezer (service code 0907994-00)

    Unfortunately this fridge freezer is just out of the 2 year warranty guarantee and has developed a fault that the Freezer only goes down to a temperature of -12C. The upper fridge section works fine. It appears that the temperature adjustment control is only for the fridge and the freezer section is automatic.

    Are there any reset procedures I can try or diagnostic modes?
    Can you please assist with helping me troubleshoot this problem. What sensors etc. can I check and when should the fan in the freezer come on. I have a service background and am happy using a multimeter.

    Any suggestions or advice would be much appreciated.
    Thanks in advance
    Pete


    Liebherr CUN3033 Fridge Freezer

    October 3, 2015 at 7:50 pm #430684
    ELDAR59
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    Hi Pete, I’d check behind the back panel in the freezer to see if there was an ice build up on the evaporator.
    That or the freezer evaporator fan not working is the likely source of a problem.

    Cheers.

    October 6, 2015 at 7:35 pm #430685
    PClem
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    Thanks ELDAR59,
    Your diagnosis was spot on, there was a build up of ice on the evaporator.
    I have defrosted the unit and normal operation appears to have been restored with the fan operation confirmed.
    If the problem should return should I start fault finding by checking continuity of the defrost heater circuit. This appears to include a thermal switch on the front of the evaporator unit, visible through a cut out in the polystyrene front cover.

    Thanks again for your assistance
    Regards
    Pete

    October 6, 2015 at 9:44 pm #430686
    ELDAR59
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    Hi Pete, hopefully your problem was caused by nothing more than a blocked evaporator drain hole.
    If the problem occurs again, then you do indeed need to be checking the defrost circuit

    November 15, 2015 at 1:39 pm #430687
    PClem
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    Hi,

    Unfortunately after approx. 6 weeks it looks like my original problem is back with the Freezer only going down to a temperature of -12C. However when I removed the back panel the ice build up on the evaporator is nowhere near as bad as last time.
    I removed the 2 pin connector to the defrost circuit and checked the circuit which appears to have a continuous reading of 386 ohms. Am I right in thinking this circuit is made up of a heater and the thermal semiconductor mounted on the front (markings: IRCA M G5 TL11 86C)of the evaporator unit. I both heated this with a hairdryer and freezer spray but the reading never changed.
    Any suggestions would be much appreciated.
    Thanks
    Pete

    November 15, 2015 at 2:27 pm #430688
    Tony R
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    I would advise you to have the freezer evaporator sensor replaced and a new PCB fitted.
    Beware the unit marked 86c is a thermal saftey device, if this trips at it’s rated temperature it will be destroyed, and need replacing.
    I would also check that the defrost water exits down the drain hole and that the drain valve is not malfunctioning.
    http://www.liebherr-randallrefrigeration.co.uk

    November 16, 2015 at 7:55 pm #430689
    PClem
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    Thanks Tony R,

    I have checked that the defrost water exits down the drain hole at the bottom of the evaporator unit in the freezer section. Can you tell me how to locate the drain valve. Will I have to pull out the fridge freezer to access this form the rear.
    Thanks
    Pete

    November 16, 2015 at 9:27 pm #430690
    Tony R
    Participant

    Re: Liebherr CUN3033 Freezer not cold enough

    Hi Pete, The drain valve is located at the rear above the drip tray, it is black in colour and looks like a teat from a babys bottle.
    It has slits in it that open as the weight of water builds up in the drain. they can become sticky and prevent the water from flowing away. But as you have stated the water does run away, I would recommend fitting a new freezer evap sensor and replacing your pcb for the latest one.
    http://www.liebherr-randallrefrigeration.co.uk

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