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recharge freezer/ fridge

Sep 10, 2012
Hunter 450 Gulfport, Florida
My freezer would not cool after being shut down for several months, worked well before that. The compressor and fan runs as does the box circulation fan. No refrigerant escapes when the shreader valve is slightly depressed, so it seems it lost charge. I ordered a gauge set, vacumn pump and adapters. The fridge was once a cold plate but now is a flat white metal panel (don't know what it is called) with one 90 degree bend to cover two sides of the box, both are cooled by hermetic compressors with air cooling. Recharging the freezer seems straight forward with Calder's refrigeration book although Calder's book refers only to R12, but two things are odd. one there are no sight glasses on either system and although they are helpful they are not required for operation. The refrigeration box plate gets cold but the low pressure line does not get more than cool. I wanted to check its charge level but discovered that there is no low side port to connect to. The freezer has both high and low but the fridge has only the high, images attached. The fridge compressor was a replacement and it was charged so how do you charge it without a low pressure port or even check charge level? Is it accomplished through the high port? Anyone seen this before?


Feb 10, 2004
Hunter 40.5 Warwick, RI
Who is the mfg of the freezer system? How do you know that the refer port is the high side?
These small systems only use about 5 oz of freon and Adler Babour systems are typically filled while monitoring compressor current.
You would do well to get Richard Kollemann's book on refrigeration.


Jan 15, 2010
Hunter Legend 40.5 Victoria
You can also post your question on Cruisers Sailing Forum in Plumbing Systems and Fixtures.
I had a somewhat similar issue in 2020 and Richard Kolleman has helped with numerous expert answers/suggestions.
Feb 26, 2009
Oday 30 Anchor Yacht Club, Bristol PA
I've been in the HVAC business my whole life what you have there best that I can tell is a BD compressor with a Schrader valve already soldered to the compressor body which means it's a low side connection and the system has been messed with before.

First mistake was depressing the Schrader valve to see if there was anything in there because, the low pressure is so low when the system is operating, you could have pulled air into the system.
These little systems only hold around 5 oz of refrigerant you absolutely need to know if it was R12 or 134 because you cannot use 134 on an older system the oil will break down and cause nothing but problems.
The biggest mistake people make is overcharging because they hold such a small amount of refrigerant.

the right way is to charge with an electronic scale that reads in fractions of an ounce.

To get any more help you will need better pictures, model and or name plate information.
If you start hooking up gauges you're going to cause more problems because there is air in the lines of the gauges and the three gauge hoses probably hold enough refrigerant to charge the system alone and it's a critical charge meaning if it's a 5 oz charge if it's off by half an ounce it will be affected.

Another common mistake people make when the system is first turned on, it can take an hour or more to actually feel any cooling in the evaporator.
Feb 10, 2004
Hunter 40.5 Warwick, RI
the right way is to charge with an electronic scale that reads in fractions of an ounce.
Is this process as simple as setting a can on an electronic postage scale, pushing the tare to zero, and then adding the Freon in short bursts until the weight goes down 5.0 oz? Or is the scale a specialized piece of equipment that only HVAC have?

And assuming that you are starting with a system that has no pressure (zero Freon) how do you know exactly the correct amount to add. The common knowledge is "around 5.0 oz". That could be 4.5-5.5 oz, and it is also common knowledge that 0.5 oz more or less has a significant effect on the system efficiency.

I'm asking because my BD3 freezer is not cooling properly and according to Richard Kollemann the symptoms and data suggest that it is likely to be low on Freon. I plan to recharge and test for leaks with a sniffer next spring, and I want to be sure to add the correct amount of Freon.
Feb 26, 2009
Oday 30 Anchor Yacht Club, Bristol PA
Nothing is simple on miniature systems. But, service the costs are just as high as they would be they on large systems if you call a professional, if you can find a professional if you professional is even interested in coming to your boat.

Around 5 oz I'm only putting that out there because that's what I've seen on the name plates. One needs to know what the factory charge.

There is nothing simple about charging, by time the DIYer buys all the equipment they could have called a professional which is why it almost always makes more sense to just replace these machines.

Everybody assumes which should not be assumed it's very rare sealed systems like these need refrigerant. The operating pressures of R134 used in a small refrigerator freezer are very very different from the pressures on the air conditioning system you see on on vehicles there is no comparison and this is why people get in trouble, they keep trying to generalize.

On your own system freezer let it run a couple hours do the wet finger touch to the evaporator see if your fingertips sticks listen for the gurgling noise of the refrigerant after an hour or so, why you're doing all this waiting you can scrutinize the box to seal on the lid and other ways that the box is not cooling.
Jul 7, 2004
Hunter 30T Cheney, KS
I had a HVAC tech come out to the boat to work on my fridge. He located and soldered the leaking line, evacuated the system and recharged it for about $200. Been working great ever since. It works too well if the t-stat gets set too low.