42DS fridge

[NZL50505]

On our annual family cruise and think my fridge is misbehaving. Sorry don’t know what make / model but it’s a 2006 SO42DS. Over last few days I noticed it wasn’t keeping stuff so warm and so I’ve tried adjusting the thermostat (in case that got knocked during loading fridge) but still not convinced. It is running but only keeping about 8-9C whereas I’m sure it used to be lower around 4-5C.

When I turn the thermostat it sometimes (but not always) switches on & off as I’d expect when adjusting the thermostat.

Or could it need re-gassing after weeks of hard work during our hot NZ summer?

Any other ideas?

Thanks

[Tafika II]

Try re-gassing it 1st...it's the cheapest. Next is the thermostat, then the compressor. We replaced the thermostat and compressor last summer and works fine now. re=gassing didn't help

[rene460]

Hi NZL, like running out of gas for the barbecue, it always happens just when you most need it.

Like Trafika, I would make a first guess that it is out of, or low on gas. If this proves to be so, the obvious question is where did it go? One clue is in your first sentence, “annual holiday”. Does the fridge get used much in between? I have always been advised that these small fridges, probably any fridges really, need to be used regularly. Something about oil seals drying out. I am not really sure of the details, as I thought most were sealed units. It will be interesting to hear what the fridge mechanic says. If the gas has leaked out recently it would be great to learn why, and anything we should all do to avoid it happening.  I assume the mechanic does a leak test before regassing in case it is a more fundamental problem.

While you are waiting for the mechanic, it might be worth checking, does the evaporator get cold over any or all of its surface? And make a measurement of the compressor current draw if you have suitable equipment. These factors provide important clues as to what is going on. No gas means low compressor discharge pressure so low current consumption. Obviously the mechanic will do these checks again, but it will be easier to understand the explanations if you have done these things yourself first.

I suspect you can also get clues to whether the thermostat is working by observing whether the unit runs continually when the setting is low. Does it then turn off when you turn it to the warmest setting? Does it cycle if the setting is consistent with that temperature it is achieving? As you will realise, I always like to understand what is going on, even though I am not able to fix it myself. And I don’t recommend spending your holidays on a research project. There is not much most of us can do on a fridge unit.

Also, if you are close to a town, it is worth putting an ice block in the bottom of the fridge to preserve your food while you wait for the mechanic. If you can get it to the boat in a cheap cooler box, it will last several days.

Rene460

[zaphod]

There are a number of things that should be checked before you get to the refrigerant charge. Is the compressor actually running? Is the condenser fan running? Is something obstructing airflow through the condenser?

Under normal conditions when the compressor is running you should hear a hissing sound as the refrigerant is being fed into the evaporator. The evaporator plate should start to frost consistently over the whole surface. If it only frosts on part of the plate it may be low on refrigerant.

If the condenser fan is not working, the condenser coil, (the radiator looking thing beside the compressor) will get hot, and the system will not cool properly because it cannot reject the heat and fully condense the refrigerant. The same would apply if there is restricted air flow to the condenser. The refrigerant pipe going into the top of the condenser should be hot, and the pipe coming out of the bottom should be slightly warm. A problem with the condenser fan or airflow can cause the compressor to cut out due to high pressures and temperatures.

If the compressor does not run, and turning the thermostat lower than your usual setpoint brings it on, the thermostat could be failing. Most thermostats are simple mechanical switches with gas filled capillary tube sensing. If that tube gets damaged and starts losing its gas, the thermostat will think the temp is lower than it is. Simply disconnect the 2 wires from the thermostat and connect them together to see if the thermostat us the culprit.

If it does come down to a refrigerant leak, make sure the tech finds and repairs the leak. It is not normal to have to add refrigerant to a system, and just "topping it up" is just a temporary fix. Hopefully the tech you get to look at it is experienced with these small systems. They are critically charged, meaning they will only operate efficiently with precisely the correct amount of refrigerant. While a really experienced tech could just top it up based on careful temperature and pressure measurements, the safest way to do it is to remove the remaining charge, pull the system into a vacuum, and then weigh in the correct factory charge with fresh refrigerant.

[sleighride]

My reefer-freezer combo went out last spring in my DS43. The refrigerator repairman started with the thermostat, then did the gas check, and finally found that the problem was the compressor fan. The new replacement fan takes less power and has led lights that go on when it is cycling properly. 

[zaphod]

Jan 14, 2019 20:30:35 GMT sleighride said:

My reefer-freezer combo went out last spring in my DS43. The refrigerator repairman started with the thermostat, then did the gas check, and finally found that the problem was the compressor fan. The new replacement fan takes less power and has led lights that go on when it is cycling properly. 

Yes, typically the last thing they will check is the refrigerant charge, because in these systems we want to avoid connecting gauges unless absolutely necessary, because every time you do, you loose a little bit of refrigerant, and there is always the risk of introducing contaminants from your hoses if you are not careful. Indeed, many small systems do not even have access ports to connect gauges to the system, so they need to be installed in order to get system pressures. That's why it is best to eliminate everything else first, and then verify refrigerant charge using temperatures. Tapping into the refrigerant circuit is the last resort.

[Syrah]

I have a similar problem with my 42ds. Nowhere near as cold as before. Fridge around 12C and freezer temp 5C. It seems like it may have got very cold prior this happening as we had a couple of drink cans explode in the fridge.

Appreciate any guidance on locating the compressor, regassing, changing the thermostat.

Regards

Wayne

[ianf]

My model is a 2006 42DS and this summer I have been through a lot of similar problems before finding a fix.

First of all the compressor location is accessed via a removeable panel at the right side of the cupboard under the sink unit.

I had similar problems with the fridge not getting cold and called in a refrigeration "expert" who just stuck some extra gas in and left after relieving me of 110 euros. It sort of worked for a few days and then packed in altogether.

Incidentally, I'm not sure you are aware but if your fridge is the same as mine there is no compressor fan. The heat is dumped through a large copper block fixed to the outside of the hull which has to be in the water to be effective so don't use your fridge when you are on the hard. You can see where the fridge pipes attach to the copper block if you lift the floor panel directly below the cooker.

Next I engaged a different fridge engineer who had been recommended after the previous debacle and he did a proper job. Unfortunately it seemed that the original engineer had bent and crimped one of the copper refrigerant pipes next to the compressor while working in the very tight space and this had caused the compressor to overheat and eventually burn out.

The new engineer also found that the thermostat wasn't working properly so replaced that and the compressor and re-gassed and tested it. Everything was fine 
but I later found that the fridge was hunting, switching on for a short time and then cutting out again so not getting really cold. I measured the supply voltage from the panel while it was doing this and found that it would drag the voltage down to about 11.5 Volts and then switch off whereupon the voltage would recover and the process would start over. To get over this, as I couldn't find why the panel voltage dropped under load, I installed a relay next to the compressor switched from the original feed and ran a dedicated power supply to it directly from the isolation switches in the aft cabin.

I hope some of this is helpful - good luck

[Syrah]

Does anyone know what sort of fridge is fitted to a 2007 42ds?

[Tafika II]

Our boat was built in France in late fall 2007, although it's classified as 2008. It had a Vitrifrigo ND35VR3-VQ (Old # ND35VR-V-GR). it was replaced in OCT/2018 with a ND35VR Compressor.

[Syrah]

Thanks ianf and Brent. Our compressor is air cooled (no copper plate). We had a detectable gas leak, which is now fixed. Unit was regassed and now appears to be working properly.

[freeflow]

Thanks for the info, our2003 43DS had the same problem and I was adding R134a every few weeks all summer.   Easy enough to add gas and fairly inexpensive.  Boat is now in winter storage and all gas has leaked out in less than 1 week.   I tried soapy water spray to find a leak to no avail.  Time to stumble through and find a pro I guess.   

[Syrah]

The guy that I used had a sensor to sniff out the leak so that he could fix it.