12volt boat fridge

[priory]

Hello everyone, although i have been a member for some time now due to technical problems i have never been able to post, but all sorted now. So here goes. Looking at a fridge on a yacht for a customer. running a 12v comp with 134a refrigerant. water cooled condensor(small one). Found unit running in a vaccum. on stopping the compressor suction pressure rises, still got some gas. thinking it has lost a bit of gas i try to charge it up and all seems well. 2 hours later my customer phones to say, its not really doing a lott and the compressor is v.hot. on checking pressure suction pressure is still ok ( 0.5 bar) cant test discharge but temp seems ok. I am unsure if this is a moisture problem/ condensor problem(air lock)/ or compressor problem. manufacturer(norwegien) said it sound like the compressor and for simplicity sake change the whole condensing unit !!! sounds pricy. I am going to recover gas, change drier and fit discharge schreader port to check this head pressure..... any one else got any ideas??

[chemi-cool]

hi priory,

yes, i have an idea,

first, i belive somewhere in the system there is a blocked cap tube or drier.
if there are no leaks, you should'nt be charging it.
second, before you recover, connect this adapter which is fastened with three little bolts to the discharge line and get the real picture instantly.

when you done, you can take it of and braze the tiny hole.

these little things (I dont know the english name) always leak.

good luck

chemi

[frank]

Got to agree Chemi - if the suction rises when you switch off after running in a vacuum and the compressor is hot due to a lack of suction gas cooling then it is probably a blockage.

[priory]

This unit had already been charged (due to leak) 2years ago, they had fitted a line tap valve (although there was a schreader on the comp) hence i thought of moisture .....l thanks you for the advice....we will see.

[Brian_UK]

these little things (I dont know the english name) always leak.

We call them a line-tap valve and as you say they always leak in time.

[Brian_UK]

they had fitted a line tap valve

So that's where it's leaking from then
But seriously you must do a leak test especially on these small systems

[superheat]

134a uses POE oil. Low side leak draws moisture. Moisture kills POE oil.
You should not need to change the whole CU. You can just change the oil in the compressor.

I have one that leaks down into a vacuum. The leak is inside the case someplace, too hard to find for the money this guy wants to pay. I drilled a hole in the bottom of the compressor and installed a tap. Now I can change the oil regularly.