Dometic RML 10.4 S troubles

[blackpete]

Hi - I’ve been singing the praises of our Dometic 3 way fridge freezer then suddenly……
I have spent a few days working through the fixes and think I have it all in hand, just waiting for the thermal paste to arrive.
I removed the aluminium plates and cleaned back the cooling tube - then put it back together without paste to test the temperatures.
I got my freezer down to -12C with the fridge sitting at +9C.
The actual cooling tube behind the freezer aluminium plate is at approx -25C.
So what difference will the paste achieve - I am obviously hoping it can make that 5/6C reduction to give me a safe fridge at 5C or less.
This was set on level 2 and I have fans on the exterior vents.
Any wisdom gratefully received
Thanks
Peter

 

[blackpete]

Sorry forgot to add that is on EHU not sure if that makes a difference - I know gaz is much better but the thermal paste temperature reduction should be about the same?

 

[Two on Tour]

Hi - I’ve been singing the praises of our Dometic 3 way fridge freezer then suddenly……
I have spent a few days working through the fixes and think I have it all in hand, just waiting for the thermal paste to arrive.
I removed the aluminium plates and cleaned back the cooling tube - then put it back together without paste to test the temperatures.
I got my freezer down to -12C with the fridge sitting at +9C.
The actual cooling tube behind the freezer aluminium plate is at approx -25C.
So what difference will the paste achieve - I am obviously hoping it can make that 5/6C reduction to give me a safe fridge at 5C or less.
This was set on level 2 and I have fans on the exterior vents.
Any wisdom gratefully received
Thanks
Peter

The thermal paste acts a contact bridge for the cold of the evaporator pipework to pass to the aluminium cooling fins in the fridge.
The paste makes contact between the irregularity in the narrow contact area between the evaporator pipework and the backplate of the cooling fins.
Applying thin application to where the two surfaces touch offers the best results, too much will reduce the performance.

 

[blackpete]

The thermal paste acts a contact bridge for the cold of the evaporator pipework to pass to the aluminium cooling fins in the fridge.
The paste makes contact between the irregularity in the narrow contact area between the evaporator pipework and the backplate of the cooling fins.
Applying thin application to where the two surfaces touch offers the best results, too much will reduce the performance.

Yeah understood but if the evaporator pipe work is -25C when the freezer is -12C without paste can I expect it to reduce the freezer temperature further or even mirror the -25C?

 

[Two on Tour]

Yeah understood but if the evaporator pipe work is -25C when the freezer is -12C without paste can I expect it to reduce the freezer temperature further or even mirror the -25C?

Applying the thermal paste will lower the temperature in both the fridge and freezer compartments, but I would expect that you could down to about -18C to -20C, but -25C woud be pushing it.
Our freezer at home is set to -18C, which is a freezers recommended temperature.

 

[blackpete]

OK that’s just what I needed thanks. I will be happy at -15 to -20 with a that the fridge dips below +5C
I think it’s been a combination of factors as we also have a door that moves more than I would like but keeping it locked seems to help. Thanks again for your input/help

 

[Sleeveless]

Best to only test for temps with the diffuser properly assembled i.e, paste applied . Regarding the thickness to apply it must bridge any gaps between evaporator tube and diffuser plate so a " generous bead " is required to achieve this or you're wasting your time. Once the two components are mated together don't pull the diffuser off again, so paste it up and slap it on . See quote from Dometic/ Norcold agent ...

Step 7: Apply New Thermal Mastic​

Apply a generous bead of fresh thermal mastic where the new cooling unit will contact the refrigerator. Don’t skimp — use all the tubes that came with your new unit. Proper heat transfer is essential for cooling performance.

 

[blackpete]

Best to only test for temps with the diffuser properly assembled i.e, paste applied . Regarding the thickness to apply it must bridge any gaps between evaporator tube and diffuser plate so a " generous bead " is required to achieve this or you're wasting your time. Once the two components are mated together don't pull the diffuser off again, so paste it up and slap it on . See quote from Dometic/ Norcold agent ...

Step 7: Apply New Thermal Mastic​

Apply a generous bead of fresh thermal mastic where the new cooling unit will contact the refrigerator. Don’t skimp — use all the tubes that came with your new unit. Proper heat transfer is essential for cooling performance.

Will follow thank you

 

[Two on Tour]

Will follow thank you

Good luck, as that goes against the experances of Funsters that have reapplied thermal paste, I'll stick by what I posted from having successfully done several F/Fs.

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These are results for what are the affects of appyling too much thermal paste to a fridge cooling fins

AI Overview
Applying too much thermal paste to a fridge's cooling fins or evaporator tubes will primarily decrease the refrigerator's cooling efficiency and create a significant mess.
Unlike a computer CPU where immense spring-loaded tension forces excess paste to squeeze out the sides, refrigerator cooling elements are typically held together by basic clips, small screws, or minor physical contact. Because there is much less mounting pressure, the consequences of over-application manifest differently:

1. Reduced Cooling Efficiency (Insulation Effect)
The sole purpose of thermal paste is to fill microscopic air pockets between the cooling/evaporator tube and the aluminum finned plate. Thermal paste conducts heat much better than air, but it conducts heat much worse than direct metal-to-metal contact.

2. The Correct Approach
You only need a very thin, uniform layer (often a thin bead or smear). It should be just enough to bridge the tiny uneven gaps where the pipework touches the aluminum plate. If you can slightly see the metal through the film of paste as you spread it, you have the right amount.

 

[Sleeveless]

When replacing the thermal paste on my Dometic, I found the new paste to be the consistency of toothpaste and had no issues trying to compress and certainly no need for any significant force, also the pic below shows the remains of original manufacturer's application of thermal paste ( some has remained on the evaporator tube and some has fallen off ) to be at least 1cm or so wide and thick enough to give a good contact area to effectively transfer heat. This confirms the "generous application" mentioned in the agent's instruction above. This I consider to be the correct approach.

 

[RM_Marine]

I've done mine a few times now since having the van (6 yrs now)

I skimped the first time and it was ok, this time i used around 20g of a 30g tube (all I had left) and it really has been better thank last time and next time would just use the full tube on the fridge and freezer.

More isnt better as alot have said, but I haven't found out what is to much (more) yet and when I do I'll let you all know.

20g of GD900 isnt to much from my findings

 

[Lenny HB]

I've done mine a few times now since having the van (6 yrs now)

I skimped the first time and it was ok, this time i used around 20g of a 30g tube (all I had left) and it really has been better thank last time and next time would just use the full tube on the fridge and freezer.

More isnt better as alot have said, but I haven't found out what is to much (more) yet and when I do I'll let you all know.

20g of GD900 isnt to much from my findings

Once you have done it it with a decent thermal past like GD900 it shouldn't need doing again, it's only the crap Dometic use that degrades

 

[blackpete]

Once you have done it it with a decent thermal past like GD900 it shouldn't need doing again, it's only the crap Dometic use that degrades

That’s the one that I have ordered.
Have you any wisdom about the application thickness - generally the thick or thin debate?

 

[Lenny HB]

That’s the one that I have ordered.
Have you any wisdom about the application thickness - generally the thick or thin debate?

Thin, just enough to make contact between the two surfaces.

 

[RM_Marine]

That’s the one that I have ordered.
Have you any wisdom about the application thickness - generally the thick or thin debate?

Ive done it thin and it was ok, but want to see if it would be better with a thicker application due to the fridge being good but the freezer only being ok

So this time Ive done it thicker and less sparingly and its been alot better

Used around 20g/mls over the fridge and freezer parts and it has been better.

As iev said I havent gone made with it to find out whats to much yet

 

[Sleeveless]

Ive done it thin and it was ok, but want to see if it would be better with a thicker application due to the fridge being good but the freezer only being ok

So this time Ive done it thicker and less sparingly and its been alot better

Used around 20g/mls over the fridge and freezer parts and it has been better.

As iev said I havent gone made with it to find out whats to much yet

Me too , when I did mine I researched the type and amount of paste to use , couldn't find any reference to applying a thin layer so I matched the width and depth of the original factory application , this stuff after all provides the thermal transfer, so with a thin application there is the risk of incomplete contact in places, as well as reducing the surface area in contact with the evaporator tube . This guy did make me laugh though ...

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