[chall03]

Our fridge is a bespoke system featuring an older Danfoss compressor( BD 3 I think, maybe BD 2 will check) condenser with fan and A Danfoss 1020N3030 control module all mounted in the engine bay.

It has worked a charm for the past 4 years including a few periods of 6+ months continuous running but of course just as we are about to head off again on some extended cruising it is causing some dramas.

When I turn it on it begins to run seemingly fine, but after a time ( an hour?) it will begin starting and stopping in a cycle where it runs for 30 seconds, squeaks to halt for 2 seconds and then seems to begin running again for another 30 seconds but the fridge does not cool....

I have a Watt meter connected to the fridge circuit that displays good voltage 12.5 12.7 and I have also tried Connecting A wire between the T and C terminals on the Danfoss control module thus bypassing the thermostat to see if it was the issue but with no change.

Open to all and any advice as where to next!
Thanks.

 

[Don L]

I would think if you are jumping the thermostat, but the compressor is still cycling that it is the control module that is bad. But that wouldn't explain why it would run for an hour upon startup before the cycling starts.

 

[aeventyr60]

Is the evaporator plate getting cold? How high up is the frost line on the plate? Can you put a gauge on it to see if has lost the R134a? I have a 1 old brain and a brand new one if you are in need...Sometime in hot environments the brains get fried. Also is it a BD 35 or BD 50 compressor?

Check the connection between the compressor and the evaporator plate..2 brass looking nut fiitings...use the correct size spanner, no stilson on these guys, they deform very easily

 

[deniseO30]

Don't, put a guage on it! Just one guage hose is half the refrigerant charge!

 

[chall03]

Thanks guys, I am suspecting the module(brain) as it sits in a hot poorly ventilated engine bay and I had heard that they are susceptible to fail in less than ideal environments.

The plate does start to cool some. Today the problem appeared within minutes of startup, I agree the intermittent nature of it all has got me beat.

Tomorrow I am going to try hooking the module directly to the batteries bypassing the boat's wiring to rule out low voltage or wiring problems all together.

Will let you know how I go!

 

[Stu Jackson]

Kollmann Marine

99% are electrical.

 

[SVAuspicious]

The plate does start to cool some. Today the problem appeared within minutes of startup, I agree the intermittent nature of it all has got me beat.

The control module could easily be failing after it reaches operating temperature.

 

[chall03]

Thanks guys....

So today's update is that I ran wiring straight to the battery, bypassing the boats electrical system and the problem still presented, as our house bank is getting a little tired I also ran it to the the starter( Optima 55ah Blue top) and the problem also presented straight away.

Also to clarify......what is also happening when the problem presents it that the fan starts, big squeak like something wants to get going, but seemingly the compressor then is NOT running( no tell tate noise or vibration, no cooling of plate) but the fan is running quite happily.

After playing the game today with about 20-25 attempts at turning the fridge on it ran normal(the compressor seemed to kick in and no 30 sec intermittent break) twice. The rest of the time there was the issue detailed above.

 

[aeventyr60]

Redo all the spade connectors on the brain..sometimes they get a bit crusty.+,_ and the two thermostat connectors. Strip back the wire a bit and see if the inside wires have gone black. Tinned wire I hope?

 

[chall03]

it is tinned wire....I cleaned all the terminals but your right I will redo terminals today.

I could go a cold beer right about now!

 

[Don L]

It's the control module or the compressor itself, but my bet is the module. That's my theory.

 

[aeventyr60]

it is tinned wire....I cleaned all the terminals but your right I will redo terminals today.

I could go a cold beer right about now!

Clean up those internal male spade connectors with a bit of fine grade sandpaper...My beer was so cold it had bits of ice in it last evening...

 

[Bill-Rangatira]

do you put dielectric grease on your connectors? help prevent corrosion and beter conductivity

 

[deniseO30]

Actually, it should be Noalox® Anti-Oxidant Compound

do you put dielectric grease on your connectors? help prevent corrosion and beter conductivity

 

[chall03]

It's the control module or the compressor itself, but my bet is the module. That's my theory.

Thanks Don.

That's my thinking at the moment as well. Time to buy a new module.

 

[deniseO30]

Thanks Don.

That's my thinking at the moment as well. Time to buy a new module.

They aren't cheap! (around $300) Kollman may have some he repaired he "wrote the book"

 

[hellosailor]

If it is something on the electronics board, that is heating up and failing after initially running fine, then you can test for that with "freeze spray". This is commonly sold in all electronics supply stores, maybe even Radio Shack if they're around. It is a can of some refrigerant type gas, you spray it on components and it ices them down, so you can find out if the problem is from thermal (overheat) failure. Then it evaporates cleanly. Probably $10-15 the can but it will tell you quickly if the problem is a component overheating.

Of course, you can also hold a finger on each component on the board and try to find the hot one, but this keeps you out of the circuit, and actually cools the parts to make sure they are working cold.

The squeal makes me think something is binding up, but the cooling spray is a routine diagnostic. Computer shops might have it as well.

 

[aeventyr60]

Actually, it should be Noalox® Anti-Oxidant Compound

Is that stuff a good face cream?

 

[Stu Jackson]

Is that stuff a good face cream?

Only on Blue Moon Tuesdays.

Dielectric grease: the most often misunderstood face cream in the world.

 

[chall03]

Just to update this thread.....I replaced the module and so far so good.

Now the new module seems to also be getting quite warm in the engine bay as well, so next project I need to look at ventilation options, or moving it....

Thanks all for the help.