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post #1 of 6 Old 3 Weeks Ago Thread Starter
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Replacing a refrigerator compressor

I have a fridge which is powered by a Cubigel compressor (made by huawei) which is very similar to the Danfoss BD35 and uses standard R134a refrigerant. I have always been quite unhappy with the compressor, the associated cooling and the high energy consumption coupled with lack of support from the manufacturer so I would like to get a Danfoss BD35 or BD50 replacement; I am looking at a combined controller/fan/compressor as found in the Dometic CU-100.

I think that I can use the existing evaporator plate as is it big enough and already installed. But I can't find any references to "compatibility" for evaporator plates. I am assuming that since both compressors use the same refrigerant which has the same thermal attributes the evaporator plates should be compatible...

Perhaps someone here could could confirm that assumption or explain why it is incorrect and I'd need to rip out the existing plate installation and replace it with a new one...


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post #2 of 6 Old 3 Weeks Ago
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Re: Replacing a refrigerator compressor

contact Pete Krieling @ HelmYachts

[email protected]

brilliant and ethical refrigeration mechanic

pay attention... someone's life depends on it
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Re: Replacing a refrigerator compressor

Hello SanderO,

thanks for the post, but it didn't really address my question; I don't want to waste the time of a professional if I don't intend on using his services. Either the evaporation plate doesn't need to be changed, in which case the project will go ahead and I'll either do the work myself or get a local expert to do the work, or the plate needs to be changed which would mean that I'll have to make do with the existing compressor.


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Re: Replacing a refrigerator compressor

I can confirm that as long as they use the same refrigerant, they are compatible. Actually, it isn't the refrigerant that is the issue with compatibility, it is the oil used in the compressor (which is different for different refrigerants).

However, your problem may be in the connection fittings. Those are not standardized, and it is likely that the new compressor will come with different fittings. You should determine this before proceeding so that you know what will need to be done to make things work together.

You can cut off fittings and braze matching ones on, but I'd leave that to a specialist with a clean shop, nitrogen purging, and pressure testing equipment. You may be able to order the new compressor with fittings that fit your existing plate.

While you are making this change, do yourself a huge favor and install a real filter/dryer in the liquid line between the compressor and evaporator plate.

You will need to put the system under vacuum, and ideally heat it, for several hours - preferably overnight - before recharging with refrigerant. If you can purge with nitrogen, that's even better.

Be careful and methodical on recharging it because there is a very narrow range between undercharged and overcharged, and it takes several hours for the system to re-equilibrate after adding/subtracting refrigerant. Fill it until it draws 5A, then let it run for several hours. See where the frost line it - you want the plate frosted, but not the line outside the box. An inch or two outside the box is OK, but any more and it is over-charged.

Mark

Edit: these small systems are usually soldered, not brazed. But still needs purging and a clean environment.

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Last edited by colemj; 3 Weeks Ago at 07:58 PM.
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Re: Replacing a refrigerator compressor

Thanks Colemj,

I think that the fittings in this case are going to be identical, but since I don't have a vacuum pump and some of the other equipment I will have a marine A/C expert do the work while i'm off doing things that I can do better and which will finance the marine A/C expert in his or her work But if I were to have to rip out and replace the evaporator it would become a much more complex job and not worth the effort. This Cubigel compressor has always been a disappointment to me; the energy consumption has been excessive and I just hooked up a pressure gauge and R134a refill kit and was surprised that it seems to have been overcharged rather than undercharged! Nonetheless a Danfoss replacement is going to be a drop-in change apart from the refrigerant connections.


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Re: Replacing a refrigerator compressor

Overcharging will eat more power than undercharging for sure. You can't tell too much from a pressure gauge on these systems, nor from weighing the refrigerant - following the frost line is the most accurate way to tell charge. If overcharge was the problem, why replace? Maybe get someone to balance the charge correctly and see how it goes from there? Make sure the airflow through the condenser is good? Cubigel are not known for being problematic.

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