ok I'm not expert on fridges but have messed around including building and installing the isotherm asu fridge in my last boat build. That was a utectic holding plate system and the electronic thermocouple failed after two years so we fitted a manual thermocouple to the existing unit.

Now the new fridge seems to have some fan system inside the fridge that blows cold air rather than makes a ice block With a utechtect plate.

so what I have noticed is that the compressor runs for half hour then shuts down but I can still here a fan running in the period the compressor is shut down hence I'm seeing my battery life last just a 24 hour period. I have 800 amp battery's
So it seems the fridge and freezer are not very energy efficent ......

can an someone shed some light on my refrigeration system?

Not much info there SA. It's probably a Danfoss compressor/control unit. These have a fan with the compressor and condenser, but that fan should only run while the compressor is running (and maybe for a minute or so before the compressor starts). Is the fan you're hearing with the compressor, or inside the fridge?

Find the control unit (will be with the compressor), and if it's a Danfoss system there will be some diagnostic LEDs. Google it up for more info, here is an example:
www.cruisersforum.com/forums/f115/plan-ahead-and-reduce-boat-refrigerator-down-time-and-repair-osts-96254.html

BUT: 800AH gone in 24 hours implies 33A continually. That seems very unlikely - I'd guess that the compressor will use about 4A when running. So maybe you have a battery or charging problem? Do you have any monitoring on your batteries?

[EDIT: missed the photo first time. I think I've seen your unit somewhere, will look around....]

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QLDCruiser said..
Not much info there SA. It's probably a Danfoss compressor/control unit. These have a fan with the compressor and condenser, but that fan should only run while the compressor is running (and maybe for a minute or so before the compressor starts). Is the fan you're hearing with the compressor, or inside the fridge?

Find the control unit (will be with the compressor), and if it's a Danfoss system there will be some diagnostic LEDs. Google it up for more info, here is an example:
www.cruisersforum.com/forums/f115/plan-ahead-and-reduce-boat-refrigerator-down-time-and-repair-osts-96254.html

BUT: 800AH gone in 24 hours implies 33A continually. That seems very unlikely - I'd guess that the compressor will use about 4A when running. So maybe you have a battery or charging problem? Do you have any monitoring on your batteries?

Yeah it's the Danfoss bd50. It is the fan inside the fridge that continues to run . I know there is one/two fans inside the fridge I will check it out further.

I never seem to have any luck with fridges and battery's!

The inside part looks like the Waeco VD14 - scroll down a bit here:
www.alternategasfridges.com.au/subpage6.html

That's just the evaporator - your compressor and control unit will be somewhere within a metre or two.

Yes that's it. anyway after testing in silence (turned the cabin heater off)! The compressor shut down for just 10-15 minutes before running again And the brushless fans run the whole time non stop.

What's the duty cycle? Ie, on time vs off time? I think you'd expect the compressor should run about 20 - 50% of the time. If it's more, there may be poor insulation in the fridge, or it might need regassing, or, if it's been running a while, it might be iced up. However, it's still not enough to explain the loss of 800AH in 24 hours. I think you might have more than one problem!

I have a Danfoss BD50 with 2 fans inside the fridge to circulate the cold air - keeps the beer nice & cold.

These fans have a separate switch independent of the compressor & I only have them turned on when I'm aboard & using the fridge - no need when I'm not there opening the fridge.

Nice work lazzarae..... It seems the fans draw bugger all. My compressor is running every 15 mins drawing 4.5 amp and my cabin is at 22degrees. I think that's the problem.
I have have turned my battery charger off and will do another load test overnight but I can see what the outcome will be. I am running the Waeco freezer as well which also seems to run alot in freezer mode although it is empty which doesn't help..

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QLDCruiser said..
What's the duty cycle? Ie, on time vs off time? I think you'd expect the compressor should run about 20 - 50% of the time. If it's more, there may be poor insulation in the fridge, or it might need regassing, or, if it's been running a while, it might be iced up. However, it's still not enough to explain the loss of 800AH in 24 hours. I think you might have more than one problem!

Your compressor shouldn't be coming on that often!! - May need regassing.

Is your compressor air cooled or water cooled?

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Lazzarae said..

QLDCruiser said..
What's the duty cycle? Ie, on time vs off time? I think you'd expect the compressor should run about 20 - 50% of the time. If it's more, there may be poor insulation in the fridge, or it might need regassing, or, if it's been running a while, it might be iced up. However, it's still not enough to explain the loss of 800AH in 24 hours. I think you might have more than one problem!

Your compressor shouldn't be coming on that often!! - May need regassing.

Is your compressor air cooled or water cooled?

I second that motion Lazza
The utechtic should run and freeze the the cooling plate solid and should last many hours
www.ozefridge.com/?page_id=22

Update .
At 0600 the battery's where at 11.7 volts!
I'm currently checking to see if the 600amp AGMs in the bow are banked with the 200 amp acid battery's in in the stern.
found all the manuals for the mixture of fridge components which brought not much light on the situation.

two strange things , one is that the fridge gets to 4 degrees and the compressor shuts off but within minutes the temp rises up to 5.7 and engages the compressor again. The insulation appears to be the required thickness.

secondly the heat exchanger mounted above the compressor? Is blowing hot air onto the compressor is that right?

my guess is it needs re-gassing ........

any my help much appreciated.

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southace said..


two strange things , one is that the fridge gets to 4 degrees and the compressor shuts off but within minutes the temp rises up to 5.7 and engages the compressor again. The insulation appears to be the required thickness.

secondly the heat exchanger mounted above the compressor? Is blowing hot air onto the compressor is that right?

IMO the compressor seems to be working OK with the thermostat cutting off & back in when required but the temp of the fridge should stay at 4 degrees for ages if you're not opening it to get beer out all the time!!

Is there a control knob to set the thermostat - make it colder or warmer anywhere?? You should be able to hear the thermostat click in or out when you turn this up or down. Have a fiddle with this.

Where are you getting the temp readings from?? It may be a faulty thermostat causing the compressor to cut back in when the real temp inside the fridge is staying at 4 degrees.

I have my fridge set so that it stays about 3 degrees - going by a thermometer inside the fridge.

Or there must be a reason why the fridge is not keeping cool - door seals or getting air in somewhere.

I'm definitely no expert but I don't think the heat exchanger blowing on the compressor would matter too much - it is to keep the coolant which flows though it at the right temp. The whole fridge area should be ventilated though otherwise the air passing through the heat exchanger won't do it's job properly.

I think the control knob from the thermostat located inside the fridge next to the fan is obsolete it has been replaced with a digital dixell prime unit which shows me temp and has a set point which I set at 4 degrees I was hoping I could ajust the rising temp point but apparently it's pre-set.

dunno it's got me stumped .

I may have to fit a temporary bulkhead inside the fridge box and see if reducing area changes anything.

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southace said..

I may have to fit a temporary bulkhead inside the fridge box and see if reducing area changes anything.

Buy a cheap little thermometer & stick inside the fridge - this will tell you if the digital readout/thermostat is correct.

Just seems wrong that it goes from 4' to 5.7' within minutes.

Or get a fridge mechanic or "someone who knows" to have a look - they're not cheap though!! Cost me $300 odd to gas up my fridge :(

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southace said..
Update .
At 0600 the battery's where at 11.7 volts!
I'm currently checking to see if the 600amp AGMs in the bow are banked with the 200 amp acid battery's in in the stern.
found all the manuals for the mixture of fridge components which brought not much light on the situation.

two strange things , one is that the fridge gets to 4 degrees and the compressor shuts off but within minutes the temp rises up to 5.7 and engages the compressor again. The insulation appears to be the required thickness.

secondly the heat exchanger mounted above the compressor? Is blowing hot air onto the compressor is that right?

my guess is it needs re-gassing ........

any my help much appreciated.

Your compressor my be cycling on the pressure cut out and not the temp thermostat . Make sure the condenser ls clean and the fan is working. Make sure there is no ice on the evaporator and if it has a fan ,it too is working. Feel the two pipes coming out of the compressor, one should be hot the other should be cold when the compressor is running. Turn the temp control right down to see if is controlling the compressor.

Id try re gassing it South Ace . Car A/C should be topped up every year or two most don't . I know truck companies top theres up every spring before it warms up.
I realize its a fridge but there much the same .

Yeah my boat aircon cost $500 to re-gas after the broke the gas line and had to re-weld it. it had a simular problem it was cycling on and off.....but usually when it's low on gas it doesn't pump any cold air.

The forum on this site: http://www.kollmann-marine.com/Refrigeration/ used to be a terrific resource for anything related to marine refrigeration. You now need to register to access it, I'd recommend you do that. Spend an hour or so browsing the forum, or post questions there.

From memory, you can tell if it needs gas by looking at how much of the evaporator is frosted once the system has been running for a while. It should be all or mostly frosted. Less than say 70% means more gas needed; if the frost extends along the low pressure line, there's too much (he latter less likely to be a problem here where you must be a licensed frig tech to work on these, than in the US where apparently anyone can buy a cylinder of refrigerant).

You'll probably need to take the cover and fans off the evaporator to have a look.

Yeah there's no frost on the lines. The aircon runs with 70% frost now it's been re-gassed, I moved the thermostat to the other side of the fridge but somehow I dont think that will make a differnce. Thanks for your advise guys!

Another update.......

Today I did some extensive research into my fridge components.......its turns out it is the Waeco cold machine vd-14n machine hooked to the danfoss bd50f compressor.

it works a little different than the utetic holding plate system.

The cold frost that accumulates on the fins inside the cold machine box gets forced up by the two fans and blown into the fridge.

Today I have moved the thermostat that controls the compressor start up to the lowest part of my ice box, it now appears now to give a cold blast for 5 minutes every hour brining the fridge temp down to my set point at 4 degrees.

Aparently this system is more efficient than the holding plate arangment in tropical conditions and large iceboxes.

i will monitor the run times from now on and hold of from re-gassing as that will cost just over $200

Next job battery's!

I meant to actually give you this page at Oz fridges if you look down the lower part of the page it might give you a few extra tips who knows
www.ozefridge.com/?page_id=28

thanks HO2 for that.

if you read my last post I have solved the problem by moving the thermostat away from the direct flow , obviously who ever fitted the system has had this problem since installation!

Now I'm getting at 6 degrees a compressor run for 7 minutes at 4.5amps till 4 degrees with shut down for 30mins And so on.

have you checked your run times of your waeco I would be interested to hear a comparison?

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southace said..
thanks HO2 for that.

if you read my last post I have solved the problem by moving the thermostat away from the direct flow , obviously who ever fitted the system has had this problem since installation!

Now I'm getting at 6 degrees a compressor run for 7 minutes at 4.5amps till 4 degrees with shut down for 30mins And so on.

have you checked your run times of your waeco I would be interested to hear a comparison?

Ive a couple of Engles in mine South Ace MB 40's 40 liters each freezers or fridges
http://www.engelaustralia.com.au/2products_details.asp?pid=22&productid=21565








Ive wired them in and there both working but need to mount the compressors still Ive remotely fitted them under the settee next to the fridge .
Id would like to wrap them in Space loft areo gel but hard to get locally I found some up in Sydney but they would not freight it down pick up only.
It will show up one day one inch of that stuff is worth 3.5 inched on the next best insulation
Its all painted in there now thats my next job after the forward cabin is fitted out
Power Consumption: 0.7 ~ 2.8 Amps each