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  1. #1
    Join Date
    Mar 2018
    Posts
    282

    Default Dometic CU84 evaporator plate totally iced up.

    Not having much luck with my fridge.

    I posted recently about the compressor running hot which seemed to solve itself.

    The fridge was cycling on and off nicely.

    Noticed over the last few days that it was running longer and slightly warmer.

    Couldnít understand it as usage hasnít changed but I felt under the condenser and it was solid ice!

    The fan that would normally blow air through the fins is working fine but was obviously just hitting the ice and blowing the resultant warmer air into the fridge.

    No open liquids in fridge.

    Any ideas why it should ice up and is it normal to have to give it a defrost occasionally?

    Thanks
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  2. #2
    Join Date
    Dec 2012
    Location
    Gone cruising
    Posts
    2,318

    Default Re: Dometic CU84 evaporator plate totally iced up.

    Did you recently cruise into warmer weather? This is fairly normal here. The fridge has to work harder (run longer), the outside air is very warm and therefore has a much higher capacity to carry moisture, which it often does (especially here in Greece). Every time you open the fridge, some of that warm, moist air goes in, gets cooled and the moisture condenses and then freezes.

    A fan blowing over the evaporator helps reduce this a lot, but even so you will have to occasionally defrost the thing. Or if you have done the £10 upgrade to a digital thermostat, you can set the hysteresis larger so that it defrosts itself (but then you need a drain in the fridge for the water to leave, and ideally not into the bilge, lest it gets very stinky very soon). Ours drains into a bucket with a few drops of bleach that is emptied every two weeks or as needed.

  3. #3
    Join Date
    Mar 2018
    Posts
    282

    Default Re: Dometic CU84 evaporator plate totally iced up.

    Interesting thought re the moisture in the air.

    We have been on board during some really heavy rain over the last few days, we don’t normally bother, we just go home.

    The boat is dry inside but I did notice the humidity % on our “weather reader” was very high.

    A bit bizarre really, wet outside, bone dry inside but display showing high humidity. Hmm.

    I wonder if the “damp” air has slowly made it into the fridge every time we open it.

    Anyway, we’re due a heat wave this week.

    That’ll give me some more data.

    Good to know defrosting is normal, thanks.

  4. #4
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,833

    Default Re: Dometic CU84 evaporator plate totally iced up.

    You might find some useful hints here http://coxeng.co.uk/heating-and-refr...ation-systems/
    Answers to some technical queries at new website http://coxeng.co.uk

  5. #5
    Join Date
    Mar 2018
    Posts
    282

    Default Re: Dometic CU84 evaporator plate totally iced up.

    Excellent read thanks Vyv but the fridge was re-gassed a couple of years ago, the connecting nuts had vibrated loose enough for gas to escape.

    I have marked their respective positions and they are as was left by the engineer.

  6. #6
    Join Date
    Nov 2016
    Location
    Lincoln
    Posts
    828

    Default Re: Dometic CU84 evaporator plate totally iced up.

    How are your door seals? Looks like a severe case of air ingress, donít forget ice can only form from moisture so unless youíve put water in the box it has to be moisture from outside.

  7. #7
    Join Date
    Mar 2018
    Posts
    282

    Default Re: Dometic CU84 evaporator plate totally iced up.

    Another good point thanks. It’s a top loader and the seal looks good.

    It does seem to be moisture related and the only things that are different are the intense rain conditions and there was a lot of soft fruit in there but what you can see in the photo is frost on top of glacial ice.

    Literally 10 minutes with my wife’s hair dryer to melt.

    Seems to be running well at the moment and I will leave the front cover screws out so I can monitor the frost.

  8. #8
    Join Date
    May 2001
    Location
    where democracy needs no guns
    Posts
    15,706

    Default Re: Dometic CU84 evaporator plate totally iced up.

    As liveaboards in UK with a front opening Dometic cu80 something, we defrost it weekly before we have food delivered. That takes just 40 minutes by putting bowls of hot water in the freezer compartment several times and wiping it dry after the ice melts. That way we don't get a massive build up of ice. The compressor presumably defrosts at the same time whilst the fridge is off, in our case not into the bilges, we put a shallow tray in the bottom of the cabinet to catch melt water during defrost. My tem gun reads 4-6C in fridge and -20 +/- in the freezer when cooled down which takes 24 hours from defrosting to normalise.
    Sermons from my pulpit are with tongue firmly in cheek and without any warranty!

  9. #9
    Join Date
    Nov 2016
    Location
    Lincoln
    Posts
    828

    Default Re: Dometic CU84 evaporator plate totally iced up.

    The unit will only defrost when off / duty satisfied so if ambient very warm the compressor will run longer and then not allow much time to defrost. As Robin has said it may need to defrost manually just before you need to fill it, also soft fruit has a lot of moisture in it, can be option to put fruit in bag but it then may sweat too much or put fruit in a cool bag as it does not really need to be stored below +8

  10. #10
    Join Date
    Mar 2018
    Posts
    282

    Default Re: Dometic CU84 evaporator plate totally iced up.

    Really appreciate all these thoughts, thanks.

    After the 35 degree hair dryer blast where ice floes were dropping off things seem to have settle down.

    Not sure that the bottle of 1996 Dom Perignon Rose Gold Methuselah will have survived the rapid changes.

    Might have to open it to see

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