Central refrigeration problem - Frigomar

[markc]

Hi, I have 3 fridges on the boat. The FB fridge is 24v only and has its own compressor. The galley fridge freezer has 24v and 240v and the saloon fridge is 24v. Both the saloon fridge and the 24v part of the galley are cooled by a central Frigomar compressor etc in the engine room. Yesterday after returning from a trip I noticed that the 24v system was not working, nothing had tripped. I twiddled the thermostat and nothing. The compressor was not running. However when switching on the breaker it seemed to be drawing 3amps. A little later I tried again and it worked, but I did notice a lot of fluctuation in current draw. The 3 solenoid coils are working. The next part was to look in the wiring panel in the engine room. I think the culprit may be what I assume is a relay, the internal gubbins seems loose and no longer held captive by the aluminum case. I'm not great with electrics so would really appreciate any input as to whether this is a likely cause. I didn't delve any further as I'm not 100% sure that there are no 240v circuits running into this panel.

 

[Portofino]

Frigomar have a very good Eng speaking tech guy on the end of a phone / e Mail .iirc called “ Johnathan “ ?

Daughter last yr 8uggered up a AC control panel and he kindly talked me through a reboot , you know hold theses two down until X flashers , 20 sec s for Y to flash the release and press Z etc .Saved buying new .

They seemed quite on it ….the long range support .

 

[jrudge]

I don’t know the answer but testing the relay is simple if you have a volt meter

The feed will run a coil. Is there voltage ?

There should then be a click.

Use a volt meter on ohms to determine if the relay has closed the contacts.

Hope all is well otherwise. The joy of repairing boats all season. I have had my share.

 

[luke collins]

Are any of the fridges working? There may be pressure switches and if it’s under or over pressure the pressure switches may be holding off the relays etc.

 

[markc]

Are any of the fridges working? There may be pressure switches and if it’s under or over pressure the pressure switches may be holding off the relays etc.

when running, everything is cold. I think there is likely more than 1 issue - the starting I think is a sticky relay. I've got in touch with Frigomar with a list of symptoms and I'll see what they say & update here

 

[luke collins]

That’s good if things are cold. Rules out on problem hopefully being the charge of r134a.

 

[jrudge]

You good news. It must be something in switching so relay / thermostats.

Most relays are standard and can be found on EBay.

 

[vas]

Hi, I have 3 fridges on the boat. The FB fridge is 24v only and has its own compressor. The galley fridge freezer has 24v and 240v and the saloon fridge is 24v. Both the saloon fridge and the 24v part of the galley are cooled by a central Frigomar compressor etc in the engine room. Yesterday after returning from a trip I noticed that the 24v system was not working, nothing had tripped. I twiddled the thermostat and nothing. The compressor was not running. However when switching on the breaker it seemed to be drawing 3amps. A little later I tried again and it worked, but I did notice a lot of fluctuation in current draw. The 3 solenoid coils are working. The next part was to look in the wiring panel in the engine room. I think the culprit may be what I assume is a relay, the internal gubbins seems loose and no longer held captive by the aluminum case. I'm not great with electrics so would really appreciate any input as to whether this is a likely cause. I didn't delve any further as I'm not 100% sure that there are no 240v circuits running into this panel.

View attachment 162237

cannot really help as i've never seen a remotely controlled fridge system, but the above pic is a simple relay, 99.9% 24VDC (could be a 12 or even 6V primary coil in there) and can be bought from any auto/electrician shop for a few euros, worth getting a couple. Just check the rating, doubt its going to be more than 15A.
Also most likely the loose bits is the metal shield itself, if not, you definitely replace it and you should be good to go!

V.

 

[markc]

cannot really help as i've never seen a remotely controlled fridge system, but the above pic is a simple relay, 99.9% 24VDC (could be a 12 or even 6V primary coil in there) and can be bought from any auto/electrician shop for a few euros, worth getting a couple. Just check the rating, doubt its going to be more than 15A.
Also most likely the loose bits is the metal shield itself, if not, you definitely replace it and you should be good to go!

V.

Thanks VAS, I took the relay out yesterday - it's 24v and 50A with 4 connectors

 

[vas]

50A??? blimey, do the cables support that 50?
EDIT: rhetorical Q, definitely not!
maybe that's why it has this metal shield on it.
Did you open it? (relatively easy to do without breaking the plastic lid if you're careful) Mind I'd just replace that and keep the one in my spares box if it behaves!

 

[MapisM]

Vas, if you enlarge the pic showing the compressor, you'll see on the motor label that its absorption is 14A.
I guess the relais was either already replaced or just used with a higher capacity because that's what they had on hand upon boat assembly.

@ markc: IIRC, Ferretti used to fit a thermal breaker for the fridge line in the 24V section of the electrical panel.
How much is that rated for? Around 20A, I suppose...?

 

[markc]

Vas, if you enlarge the pic showing the compressor, you'll see on the motor label that its absorption is 14A.
I guess the relais was either already replaced or just used with a higher capacity because that's what they had on hand upon boat assembly.

@ markc: IIRC, Ferretti used to fit a thermal breaker for the fridge line in the 24V section of the electrical panel.
How much is that rated for? Around 20A, I suppose...?

Hey P, the breaker on the panel is indeed less, 16a. The relay is OEM, I have found the wiring diagram

 

[MapisM]

The relay is OEM, I have found the wiring diagram

Fair enough. It surely doesn't hurt if the relay is rated for much more than he will ever handle, considering that above 16A the breaker woud trip.
Interestingly, I see no mention of AC supply - according to the diagram, everything seems to be feeded by 24VDC.
If you are that the galley fridge can run on either AC or DC, I suspect it might have its own separated compressor...

 

[markc]

Fair enough. It surely doesn't hurt if the relay is rated for much more than he will ever handle, considering that above 16A the breaker woud trip.
Interestingly, I see no mention of AC supply - according to the diagram, everything seems to be feeded by 24VDC.
If you are that the galley fridge can run on either AC or DC, I suspect it might have its own separated compressor...

The fridge freezer has a separate 240v compressor, separate to this system, with separate cooling plates in the appliance.

 

[MapisM]

Aha, I see.
Sounds like its motor always runs on AC, probably with a dedicated inverter providing AC from 24V DC when neither shore power nor genset are available.
Not that this is relevant to the troubleshooting of your problem, but if nothing else I don't see reasons to worry about AC circuits running somewhere near the motor+compressor in your first pic, which are DC-only instead.
BUT, don't even think to ask me a refund in case of electrocution!

 

[markc]

I'm resurrecting this thread as despite the fridges having behaved themselves for a year, the problem is back, just in time to coincide with the summer! All was working fine for about 5 days then it stopped. I have swapped out the relay, and it's not that. There is power to the relay and the coils, but not to the motor. I am assuming that something is preventing the relay from switching. Logically, as there are 2 fridges, each with a thermostat, I can't imagine that both failed at the same time. That leaves 3 things as per the wiring diagram, items 13 to 18 which seem to be a frost sensor, valve / coil for defrost and a defrost timer. I'm assuming these are automatic defrost functions because there's no obvious way to control these. I would appreciate any tips on either testing these - not sure if I should jump them, disconnect, which one first etc...

 

[jrudge]

I would put a meter on them to confirm they are on / off as opposed to resistance

If on / off then I would either short them if off or disconnect if on and see what happens.

Worst case you can hard wire the pump via the thermostat which as long as it is able to switch the current would be fine. If it can't then you can wire the thermostat to trigger the relay by removing it and doing a hack wiring job.

 

[markc]

Thanks Jeremy. I tried all of the above... a good learning experience as I'm not super confident with electrics, but to no avail. I didn't give up and decided to start testing again from scratch. I think I must have originally taken my reading for zero power to the motor from the wrong place, because this time it was showing power. I though I'd inspect the brushes, and hey presto, one had completely worn out. Replaced both brushes and all works again. Glad I had spares on board!

 

[jrudge]

Good news. I carry many spares but not fridge motor brushes ! Well done !