Replacing Keel Cooled compressor with Air...

[swisscraft]

Hi,

I'm in Grenada and my compressor died, there are just Waeco Aircooled (Compressor is a BDF 50) available. Since my fudge/freezer is Frigoboat and I cannot get this unit in time the fridge guy (which seems very competent) has to solder connections to fit the new compressor.

He recommended to keep the keel cooler in place, even if the new unit is air cooled. He says there is no much more effort to solder that in as well since he has to do it anyway and it should be more efficient.

Any toughs about that?? Thanks

[Richard Kollmann]

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I would have to question the competence of refrigeration guy as only one in maybe 1,000 BD compressors actually fail unless seawater gets into refrigerant. What signal are you receiving from troubleshooting LED? I would want confirmation that compressor has actually failed first. Three or four LED flashes every 4 seconds could mean too much refrigerant or even capillary tube blockage common on Keel cooler Frigoboat units. I have seen more than one compressor/condensing unit replaced on that system that did not correct a problem. If LED never flashes does compressor get warm if left on for 30 minutes? Frigoboat may not have installed this LED but if present compressor is a BD35 or BD50 service guy would have connected his LED to confirm compressor amperage is cause of compressor failure to run. If compressor runs with little or no cooling it is a refrigerant flow problem not a compressor problem on Frigoboat units.

As to connecting air cooled and water cooled condensers in series yes it can and has been done on keel cooler units.

[swisscraft]

Richard - THANKS VERY MUCH!

To finish that story: Richard was as usual right, when I when trough the whole system myself as described by Nick (http://www.cruisersforum.com/forums/...our-54872.html) the compressor was running again! I replaced now the R134a while heating the evaporator and it works better than ever!

The local Fridge guy was somehow disapointed that I could fix it afterwards, but I think he was keen as well to learn something. To his defense, he worked very methodical and was still better what I heard from other guys traveling the islands. So I guess this issue is now on his list and next one will be served better.

I used the new bought compressor for the fridge compartment so I have now a spitted unit instead of a spill over. I know this will use more power, but despite the fact that the fridge was not always that could we have now a second system. Since we will travel more remote islands and I consider the fridge as basic, I sleep now better since both system may fail hardly at the same time.

[swisscraft]

Hi there,

the compressor worked now for a few days flawless - now it stopped again with three flashes at the LED. I had issue to get it running again. After let it sit for a while it started again and works now. I'm really confused: The refrigerant is changed and should be clear. The question is now what too check next, I mean now its running but I guess it will fail again if I do not find the error. System seems not to be leaking (soap test).

Would adding a bigger dryer filter help or anything else you recommend? Thanks.

[Richard Kollmann]

Three flashes of LED and repeated every 4 seconds indicates amperage is too high probably on compressor start up. Typically this overload is caused by too much refrigerant or poor condenser/keel cooler cooling. Is there frost on line coming out of evaporator and if so how far does it extend towards compressor?

Because the troubleshooting chip has only memory for one trouble the first trouble like low voltage, may be masked over by high amperage on a quick restart.

Does this unit have the standard snap action thermostat?

Changing filter will not change anything unless it has frost on it caused by a restriction.

[swisscraft]

Thanks for the quick response Richard!
- yes there is was frost on the line coming out of the fridge (not now as the is just started to run a few hours ago - but some condensing water indicates there was maybe more)
- Regards the cooling, I'm currently in Grenada and yes the water is pretty warm! The compressor itself has now 125 F, but it can get hotter I guess (runs on low rpm, freezer plate shows -4F)
- I guess we can rule out low voltage for the moment as I'm on shore power and have something around 12.9V at the compressor)
- The unit runs with an SSC Speed control board (currently low rpm) and a digital costal MK 2 thermostat.

thanks

[Richard Kollmann]

Temperature of compressor 125º F is not a problem

Thermostat’s differential setting could be cause of overload shut down. All electric compressors require a pressure equalization period of from 3 to 5 minutes before compressor is restarted. Normally a standard thermostat’s differential is anywhere from an evaporator temperature rise of 10 to 20 degrees. Try to increase Differential to 5 minutes off time between cycles and see if this does not solve problem in the tropics.

[swisscraft]

This damn thing is starting to drive me nuts!
yesterday night I watched the freezer temperature going up to 40 F and the the compressor stalls - 3 flashes

After letting it cool down for two hours it worked, now the same issue: Compressor runs full speed, evaporator temp is dropping to 40F (i normally measure -10F there) and then the compressor stalls.

The compressor draws somtimes almost 10 amps and after stalling it takes several attempts and after one hour it may starts again until the freezer goes down to 0F as planned. I assume its now the compressor (do not know what else). But maybe the vacuum and replace refrigerant of the system was bad or....

The problem is, locally I just get Waeco coolmachines. Not sure if they run with the Frigoboat SSC Controllers and I have to weld connections if I like to keep the keel cooler. Guess the Costal Marine Digital Thermostast will still work with Waco.. Since I do not trust the local guys anymore I'm not sure what to do.

Choice A) Buy a new Waeco compressor (5-600 US) get the guy weld the connection for the Frigoboat connectors to the keel cooler and maybe add an additional Filter/Dryer at the same time). Hope this will work and the problem is not with the evaporator or the keel cooler.

Choice B) Rip everything out and buy new (with an new evaporator) (1200 USD). Forget the keel cooler and do the whole stuff myself- I would end up with two air cooled machines in the locker (waeco cool machines)

I have now a BDF 35 compressor with a VD vented cool plate for the 200L fridge, works fine. I guess the freezer has +/- 100L - need now to decided on which compressor and evaporator - or are there any other ideas??? Thanks.

[Richard Kollmann]

On a Danfoss BD compressor installed in a refrigeration unit where troubleshooting LED flashes three times, it is identifying an overload amperage condition.

From your reports replacing compressor/condensing unit may not correct problem if caused by SSC or electronic thermostat incorrectly switching thermostat off and on.

It also will not change overload condition if refrigerant charge is again incorrect on new unit.

First, I would contact Rob at Frigoboat USA as this problem is not new. If he can not help you I would disconnect wires from Danfoss module terminals C and T and install a standard snap action thermostat. If this does not solve problem I would reduce refrigerant charge a little more and see if this does not solve problem.

[sfnz]

having worked on more than a few of these systems and found a few issues constantly popping up, In New Zealand we receive cruisers after a diagonal crossing (usually from west coast USA or panama) of the pacific, couldnt get a harsher case of constant use if you tried. The danfoss compressors are a bloody sturdy wee beast to say the least, problems arise mostly from installation or air ingress to internals, air contains moisture which in turn clogs capillary tubes, creates acids and sludge etc etc . The capillary tube used is really quite tiny and takes bugger all to block therefore the total absence of air and other contaminants is critical. Have found on more than one instance where the system contained considerable noncondensables, whether this was a result of a factory/ manufacturers issue or due to instalation etc is not always clear, one thing that is clear though is that the connectors will in time leak, and in all reality most when installed never come out unless it's for troubleshooting/ maintenance issues, have also found the seal when disconnected can and will leak so why bother having them there !!
Another issue that Richard mentioned a while back is with regards to fans and electrics, even though your unit is " keel cooled" the compressor still requires a small fan to flow cooling air over the electrics and remove some compressor mechanical heat I would advise to fit one as it does make a helluva difference.
Thermostats can be roughly fine tuned for hysteresis (diff between switch off and switch on) by partially insulating the thermostat capillary with thin plastic tube leaving the evaporator end of it exposed where it contacts
My recomendation would be to
1/ remove refrigerant charge and weld out ALL connectors and change the drier
2/ Vacuum the system for 12hrs(overnight) minimum
3/ Make sure there is a fan at the compressor (cools electrics and does to a degree remove mechanical compressor heat
4/ add recomended charge of 134A ( have found everything from R12 to R404a and in one instance R22 in these systems)
5/ cover thermostat capillary with thin plastic tube completely except where it contacts the evaporator
6/ discard original access port cap and replace with 1/4" flarenut and flare bonnet ( make sure that "whoever" checks the access valve doesn't leak after gauge removal)
That should give you a totally sealed system with few if any weakpoints...............enjoy