Refrigerator/Freezer Problems

[CAVOK]

Looking for advice on a continuing refrigeration problem afflicting our 1 yo Beneteau Oceanis 46.1
From the outset our compressors have been running 24/7 and temperatures are totally inadequate. Freezer 0c and fridge 15-20c. Whether we are on shore power or on anchor it seems to make no difference. I’ve had tech look at it but they can’t fault the mechanics of it.
My question is if there was a large voltage drop on the power cables to the fridge and freezerndue to inadequate gauge wires or bad connectors, would that affect the cooling capability of the fridge and freezer, which run off separate units

[OzeLouie]

Assuming the cabinet is adequately insulated and the refrigeration equipment is sized to suit the project, then your suspicion regards voltage drop (power supply) could be correct and the cause of the poor performance.
Power supply issues are the most common cause of 12 / 24VDC refrigeration system failures.
You may check and the compressor is running, but does it continue running to complete the cooling cycle or not?
To explain: The MDM (motor driver module ... black box) at the compressor monitors and protects against low / high voltage, over load, over heat etc and these 'fail safes' are auto resetting so you can have a situation where a poor power supply can allow the comp to run for a short period, cut off prematurely then start again etc. Effectively running in increments and therefore not performing correctly.

To check:
Using a good multi-meter connected to the negative and positive terminals (- & +) on the MDM read the voltage before and when the compressor starts or attempts to start.

The voltage reading with no load, before the compressor starts is meaningless but do note that no-load voltage.

Next, continue to monitor the voltage as the compressor starts or attempts to start. If this voltage drops away by say a volt or more or below 10.9 volts then that is confirmation that most likely the power supply is the problem .


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[krid2000]

Originally Posted by CAVOK

From the outset our compressors have been running 24/7 and temperatures are totally inadequate. Freezer 0c and fridge 15-20c. Whether we are on shore power or on anchor it seems to make no difference. I’ve had tech look at it but they can’t fault the mechanics of it.

My question is if there was a large voltage drop on the power cables to the fridge and freezer due to inadequate gauge wires or bad connectors, would that affect the cooling capability of the fridge and freezer, which run off separate units

Regarding your direct question: did you actually check the voltage where you suspect the voltage drop?

More likely reason: Did you check if you need to add refrigerant to the systems?

[CarlF]

Is the entire evaporator covered with frost? (if not, the refrigerant charge is likely low from a leak) This is for Frigoboat but should be mostly applicable to you:

https://www.coastalclimatecontrol.co...guidelines.pdf

Here's how to check the voltage https://www.coastalclimatecontrol.co...50_systems.pdf

[Anna Sail]

If your system runs continuously, then power is not the issue - it's running. If there is not adequate voltage, then the MDM will shut down the system and if you have a LED (a compressor fault indicator) connected to the D and + terminals it would blink one time to tell you compressor shut down for low voltage issue.


However, your system is not shutting down. What are your set points? It could be running non-stop because it hasn't reached the set point. If you adjust the set point to the actual box temperature, does the system shut down?


The earlier links sent to Coastal Climate Control's refrigeration troubleshooting guide should help you, assuming you have a Danfos/Secop system.

[CAVOK]

Hi
Thanks for your replies.
To quickly answer your queries.
Yes the plates seem evenly covered in frost. We have defrosted them but it hasn’t resolved the problem.
The compressor runs and it’s fan seems to run at appropriate times.
The radiators are perfectly clean and the enclosure doesn’t seem overly hot.
There are compressors for each unit (fridge and freezer)
With all that neither fridge or freezer keeps cold enough. 15-20c for the fridge and 0-2c for the freezer. Outside air temperature doesn’t alter that much.
I’ll go through the links, but am about to pull this Beneteau screw up and start again. How they sell boats has me baffled. Very sadly, they have the quality control of a Russian work camp in the 50’s.
If they stood behind their product they’d have a Customer Hotline, instead of hiding behind their agents. If you can find one please let me know.
Rant complete! I’ll have another hot beer and settle..

[James M B]

So I have had my 2008 Benteau 373 (built in Marion, SC) with Seafrost system since new.
It has separate top load freezer, and front load fridge. Both powered from one unit (12 volt air cooled)
In the winter when the lake water is 42f and outside air temp is same, the fridge section will actually freeze items.
In the summer when lake water is 84f and outside air temp is 90f fridge is barely cool.
Freezer section always freezes, but in the summer I can put things on the shelf next to the hull and those items may, or may not freeze (in the freezer).
Bottom line I am convinced there is little or NO insulation between fridge box and hull. Bottom half of fridge box is below the water line.
I have yet to run across a post anywhere where someone has figured out a fix.

[krid2000]

Originally Posted by CAVOK

Yes the plates seem evenly covered in frost. We have defrosted them but it hasn’t resolved the problem.
The compressor runs and it’s fan seems to run at appropriate times.
The radiators are perfectly clean and the enclosure doesn’t seem overly hot.
There are compressors for each unit (fridge and freezer)
With all that neither fridge or freezer keeps cold enough. 15-20c for the fridge and 0-2c for the freezer.

Besides poor insulation, you might actually have too much refrigerant in your system. This can have the following effects:

• increases the pressure on the low-pressure side of the system and thus increases the boiling temperature of the refrigerant which leads to less heat extraction through the evaporator and
  
• extends the freezing line beyond your evaporator, i.e. outside of the fridge/freezer, effectively trying to cool down the outdoors. You can probably check this by feeling the copper line that goes out of your cool box.

That's what happened to my system when I first refilled (= overfilled) it. I've since gotten better pressure gauges and was able to reduce the refrigerant pressure so that the boiling point is lowered ("evaporator gets cooler") and the freezing line is inside the cool box and not outside.

I've found the three YouTube videos of "Emily's and Clark's adventure" about explaining and refilling the refrigeration system very helpful for understanding how the system works plus how to refill it properly. You might want to check them out!