Fridge suddenly stopped!

[TOM]

We purchased our boat Nov 08 and are preparing to leave Oz {Sydney} in April for our 5 year circumnavagation, Me the Wife and 3 year old Daughter. Our 12m steel sloop is not young but has been well looked after. Recently we have had a few things break all understandable and i have fixed myself .However our engine driven fridge which was working a treat {ice cold beer in 35mins!} has suddenly decided to stop working we have a 12v system as well but realey do like the eutectic.
When i switch it on it works for about 2 mins then the reset button cuts it out ,if i wait a few mins and hit the reset button it starts again but only for a short time.
Im hoping someone else has experienced this problem and could offer some advice before i call a mechanic that is likely to cost $$$$$$ .

Any advice would be great thanks.

Tom.

[Richard Kollmann]

If it is the high pressure switch that trips it would be caused by poor or no cooling water flow.
If it is the DC 12/24 volt circuit breaker that trips then either the compressor clutch coil is shorted or there is a short to ground in the refrigerator wiring.

[TOM]

Thanks Richard, although that sounds quite tecnical it is a good starting point for me and i appreciate your responce .It is interesting that all this happened after we had the boat hauled out to get work done on the cockpit drains ,so we had a Shipwright crawling around the engine bay im concerned he may have broken something I did notice that the black dome shaped thing {would assume this was the copressor} was getting very hot .I suspect it is the 12/24 circuit breaker that is tripping so there may be a short somewhere?

[Pblais]

I think Richard outlines the possible problems well. If the cooling is poor it cuts out to save itself from total thermal destruction. 2 minutes sounds about right. A short is an electrical fault that also trips the reset. They both cut the power.

You'll need to investigate why. If you can prove the cooling is working then it leaves an electrical short. The compressor will get warm even when it works properly. I would hold off going after the guy that was on your boat until you get the reason determined.

[Richard Kollmann]

Tom, you said it was the engine driven refrigeration that trips off and not the second system's electrical compressor which is now cooling the box, is this correct?

An engine driven compressor is driven by a belt off engine crankshaft. This engine driven compressor has an electrical clutch that is supplied power from a DC circuit breaker. In order for the clutch to receive power there are generally three other switches in series that must be closed, the thermostat, a high pressure switch and a low pressure refrigerant switch. If it is the engine driven system circuit breaker that is tripping there is a short to ground somewhere. Troubleshooting for this problem is to first disconnect the compressor clutch wire and reset breaker. If breaker still trips the problem is in the wiring from circuit breaker. If breaker does not trip the clutch coil has failed and must be replaced. Most of these systems use the engine water pump to cool refrigeration condenser but you may have a 12/24 volt pump connected to the same circuit breaker as the compressor clutch, if so it may have failed.

[TOM]

Hi , Richard Yes it is the engine driven system that is tripping the switch {grey box in pic} Im a bit confused that you say in order for the compressor clutch to work that the thermo ,hp and lp must be closed {are these the 3 taps in the pic one does say hp } surely if these were all closed the system would not work at all?
I have since found out that the system is probably 20 years old but all the pipes look good and the copressor and condenser all look in good cond,but the little grey box that has the reset button looks old,are these easy to replace will the gas run out if i disconect it. i think i have located the wiring to disconect the compressor clutch and i will try that when next on the boat.Would really appreciate if you could clear up the "off" thig with the switches.

Thanks again. Tom.

[Richard Kollmann]

Tom,I dough that you have a clutch or electrical problem. The gray box in picture is a combination high and low pressure switch in one box, its purpose is to stop compressor at 200 psi before system explodes. For this switch to trip there is refrigerant blockage or the seawater that cools condenser is inadequate.

Because problem occurred after boat was worked on there is a chance that one of the hand operated shut off valves in picture has been closed. There are four hand valves in picture but I can not determine from picture what each are for but there will be one on each side of the bright blue filter at top left corner of picture. Both of the filter valves must be open full counterclockwise.


Test to determine if seawater cooling is adequate. Find seawater condenser I do not see it in picture. Turn unit on and when it trips pressure switch feel refrigerant tubing coming in it will be hot. Then feel refrigerant line coming out it should be around 100 to 115 degrees F.

[markpj23]

Since the problem started after the boat was hauled out, the salt water cooling system might be air-bound? If water is not passing through the condenser it will trip off as Richard has said.

[TOM]

Thanks again for the great advice, its now starting to make more sense as there is copper pipeing coming out of the grey box so it must be a pressure switch. Im back on the boat this Friday and pretty excited with the new information on trying to fix it .The real truth is my wife does'nt reakon I can {have not told her about the Forum!} She thinks im working all this out by myself! which is good as i need to impress her with my mechanical skills before She will let me take her aroud the world.

[Pblais]

She thinks im working all this out by myself! which is good as i need to impress her with my mechanical skills before She will let me take her around the world.

Not a bad approach provided you can actually fix the fridge. It's an all or nothing type of thing. One of the rules of the Admiralty apply here: The Admiral knows when she is right so don't ask to be reminded.

Lots of hekp can be found here. If you can stick to it you can get better.

[Sandero]

I had the same symptons with my Grunnert Caribbean. it was the clutch coil which went south was drawing too many amps and popping the breaker. The fix was a few hundred bucks and it works like a charm again.

[Richard Kollmann]

defjef, Troubleshooting is a process of elimination first step was confirm problem area . Now that it has been confirmed that high pressure/low pressure switch is tripping and not the circuit breaker this should eliminate a wiring short or clutch coil failure. Attention should now be to see if there is a refrigerant flow or a high pressure problem. After pressure and flow are eliminated we can go to the next step.

[Sandero]

Roger than RK. Many symptoms can present for different underlying causes. I didn't mean to imply that it had to be the clutch coil, only that this was my experience.

[TOM]

Hi Richard, been onboard for the last few days and was pretty confident i could sort this problem out but still no luck. As you advised I checked that all the taps were fully opened one of them was only half open so i opened it all the way but stil the copressor cuts out.I have a strong suspicion that there is a problem with the cooling to the condensor if so could this be causing the high pressure problem? and how do i identify this,I{m presuming that the system is salt water cooled} . I have attached a couple of pics . The compressor is just out of picture bottom RHS the black thing with R404A ON It i assume is the condensor {this gets very hot very quickly when i turn on the fridge and before it trips. There is another black dome shaped canister alost identical but just a bit smaller closer to the actual fridge itself and near the pressure switch which also gets very hot, could the system have two Compressors?
In between all this is a long blue metel cylinder about 1and a 1/4 foot long it has what appears to be water hoses running in one side and out the other I know it has something to do with the fridge as it has a manufacturers name on it {who are no longer in the business}nothing seems to happen to it during the short time the system runs but it looks like some sort of heatexchanger.
Sorry about the long winded post but would once again appreciate any help/clues you can give me on where to look next.
Tom.

[Richard Kollmann]

Tom, the pictures still do not show the engine driven seawater condenser. If the electrical compressor was not turned on one of the hot objects you felt would have been the engine driven system’s seawater condenser. If both refrigerant lines connected to condenser were hot then the problem is excessive refrigerant pressure caused by poor seawater cooling. Some systems use an electric pump to circulate seawater through condenser. Either the pump is not working or for some reason water flow is restricted.