Samsung RS21DCNS evaporator core frosting up

[cdx]

Hello folks, new to this forum and hoping someone can help with some suggestions. Its the usual Samsung RS21 “freezer OK but fridge not” scenario. The unit is about 2.5 years old.

I have had the water dispenser freeze up and have defrosted the fridge evaporator core / fan a couple of times previously, and in the past this has lasted quite a while – a matter of months. Not so this time – I last manually defrosted on 30 April 07 and tonight the telltale ticking started when the fanblades started to catch the ice building up. Ive defrosted it all manually again straight away and this time done a few tests:

Heres what I know:

1) Fan is still working OK, no damage.
2) Thermal fuse has continuity = OK.
3) Defrost sensor resistance changes as sensor is heated / cooled
4) Metal drain at base of evaporator has never frozen up
5) Top half of evaporator core was completely frosted up.
6) Bottom half of evaporator core was virtually frost free.
7) Some light icing in fan shroud causing telltale ticking of blades
8) Drain hole in fan assembly virtually blocked with frost with some icing
9) Temps in fridge and freezer are correct for user settings

What Im guessing:

The evaporator cover might be waterlogged (and it does retain some moisture in the polystyrene when defrosted), so theres a possible evaporator cover issue here. BUT… the main issue seems to be that the top half of the evaporator core is heavily frosted up (and it has done this quickly) suggesting a defrost cycle problem. Or… is the drain hole in the evaporator cover freezing up causing the fan circulation to drop, thereby causing the core frosting?

I dont know what the defrost sensor resistance should be at various temps. Is it out of calibration I wonder causing a defrost cycle that is too short? Im thinking that it is cheap enough to change to rule it out anyway.

Hope Ive included enough diagnostic info… Any thoughts on this much appreciated.

Jon

[helo_75]

Re: Samsung RS21DCNS evaporator core frosting up

you never mentioned the defrost heater?

didnt u check it?

i would, personally…

[cdx]

Re: Samsung RS21DCNS evaporator core frosting up

Hi helo,

Knew I missed something – the defrost heater is showing resistance, about a couple of kilohms if I remember rightly. Certainly not open circuit…

Jon

[helo_75]

Re: Samsung RS21DCNS evaporator core frosting up

then if its iced up at the top, and u want to cure it.. change the sensor, the thermal fuse, and the evaporator cover assembly.. that’ll more or less hit the nail on the head

the sensor , btw is the one buried in the fluffy ice at the top, with the yellow wires

the new evaporator cover comes with a fan, with a slightly bigger hole for drainage, so it does helpt o change it

hope this helps

[cdx]

Re: Samsung RS21DCNS evaporator core frosting up

Thanks for the suggestion helo. Ive got one more bit of information, gained this morning. A fault code test (press & hold both buttons at top etc) shows the middle horizontal segment (only) to be lit, on the fridge side, right hand side digit. Is this of any use?

[helo_75]

Re: Samsung RS21DCNS evaporator core frosting up

yep.. hang on for mac or r600a, theyre the samsung guys.. they’ll be here at some point, i dont have that info to hand

[Mac1982]

Re: Samsung RS21DCNS evaporator core frosting up

Helo _75 hit the nail on the head-sensor, evap cover assy and thermal fuse need replacing.

If ure qualified to do it yourself, speak to Spares@ to get the parts

[cdx]

Re: Samsung RS21DCNS evaporator core frosting up

Thanks Mac and Helo for the replies. I will be shortly winging spares@ an email for some parts as you suggest…

Im not planning to skimp on the repair, far from it, but Im curious as to why you suggest the thermal fuse should also be changed? For sure, its a cheap enough part to change, but just wondered why you thought it needed to be changed when it is not open circuit?

Familiar with A/C & refrigeration but not with the Samsung range – so thanks again for the suggestions and advice. Its appreciated.

Jon

Oh and PS – did the single horizontal segment on the fault code mean anything? I guessed not as it didnt show dS etc. But I thought they were blank if no code…

[admin]

Re: Samsung RS21DCNS evaporator core frosting up

Hi CDX

Centre line meads defrost failure in the past 8 hours,normally due to defrost sensor failure or heater failure.

Bryan

[cdx]

Re: Samsung RS21DCNS evaporator core frosting up

r600a wrote:Hi CDX

Centre line meads defrost failure in the past 8 hours,normally due to defrost sensor failure or heater failure.

Bryan

Bryan thanks very much for that info – its very helpful. Time to order some parts I think.

Just curious, but if in future the defrost heater (evap core) needs changing is it a complete evap/heater unit replacement or can the defrost heater be swapped out without breaking into the system?

Cheers

[helo_75]

Re: Samsung RS21DCNS evaporator core frosting up

yes, it comes attatched to the evaporatr!!! with a bit of tact, the heater can be taken off, carefully and refitted to the original evaporator

if you order an evaporator from samsung, it comes with the sensor, heater and thermal fuse, to eliminate further problems

not that expensive either

[cdx]

Re: Samsung RS21DCNS evaporator core frosting up

Cheers helo and all who have posted a reply to my query…. Im really impressed at the willingness to help on here. What a find this site was – well worth a recommend.

Thanks guys 😀

Jon

[thenewts]

Re: Samsung RS21DCNS evaporator core frosting up

Hi all. My mate’s got exactly the same problem as listed above. Can anyone supply a link to where the spares mentioned above are available? I.e. Sensor, Thermal Fuse and Evaporator Cover + Fan.

Many thanks.

[kwatt]

Hi,

Samsung bits are HERE

I dunno if the cover is in there right now but, if not an email to Dave on spares@ukwhitegoods.co.uk will soon sort one out for you.

K.

[THE BLACKSMITH]

Hi Guys, Can anyone tell me how to get the evaporator cover off! I appear to have the same problem but can’t get past the 4 screws.

[Author]

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