Eutectic Fribge

[Nick D]

Hi All,
I bought a30 ft Farr with retractable keel and keep it on a trailer.I have not sailed it much due to lack of time but every time I do and turn the fridge on it makes the engine revs drop to almost cuttting off and dose not get cold.it is an eutectic fridge that works off the engine,any idea what is causing this.
Thanks Nick.

[Oceanride007]

All diesels AFAIK have a governor between your speed control cable and your fuel rack. There is a droop in speed characteristic that will drop your revs with sudden increase in load. Could be the Compressor load is huge, may be mechanical defect, maybe your governor not working well.

Does increasing Fuel throttle setting help, when you are starting Fridge compressor. Don't know much about electro mechanical clutch defect. But if its compressor $$$ for someone to have a look. You don't see these kinds of compressor drives anymore for good reason.

[OzePete]

Originally Posted by Nick D

Hi All,
I bought a30 ft Farr with retractable keel and keep it on a trailer.I have not sailed it much due to lack of time but every time I do and turn the fridge on it makes the engine revs drop to almost cuttting off and dose not get cold.it is an eutectic fridge that works off the engine,any idea what is causing this.
Thanks Nick.

These systems are very much out dated but can still do the job if set up correctly. Assuming the compressor is actually rotating, I suggest you have a fridgie check the compressor oil, leak test the system, (repair any leaks) replace the filter drier, evacuate and re-gas. It is likely the system has a guts full of air which pushes the compressors head pressure extremely high and as a direct consequence the compressor load will be abnormally high.

Cheers OzePete

[Alan Mighty]

Originally Posted by Nick D

I do and turn the fridge on it makes the engine revs drop to almost cuttting off and dose not get cold.it is an eutectic fridge that works off the engine,any idea what is causing this.

Welcome to CF, Nick.

I assume you've an engine-driven refrigerator compressor, probably with an electro-magnetic clutch.

What's the power rating of that refrigerator compressor? I'd guess it to be somewhere in the range 3/4 horsepower (0.6 kW) to 2 hp (1.5 kW).

What's the power rating of your auxiliary engine at the engine speed (rpm) at which you're engaging the refrigerator compressor?

If your yacht's auxiliary engine is only at idle, producing perhaps 3 or 4 kW, then the load from your (perhaps) 1.5 kW compressor would of course drop engine rpm. And perhaps even bring a diesel engine - if that's what you have - close to lugging. If you increase the engine rpm does the engine respond?


As for your fribge not getting cold, for how long have you run the engine-driven refrigerator compressor? What are the heat loads associated with your fribge: what is it's ambient temperature? what's the volume of the fribge? at what temperature is the thermostat set?

The jobs you're asking of your engine-driven refrigerator compressor are:

first, to pull the temperature of the holding plate down from ambient to some sub-zero temperature;

second, to respond to a signal from the fridge thermostat to electro-magnetic clutch to disengage; and

third, after heat from your fribge has warmed your holding plate up again (as your fribge or icebox has cooled down), for the thermostat to signal the electro-magnetic clutch to engage the refrigerator compressor again.

I don't know your ambient temperature and so on, but I'd guess that those three steps might take as long as 45 or 60 minutes.

For how long have you run your refrigerator compressor?

Does your compressor have a sight glass through which you might be able to see a bubble?

What heat exchange mechanism do you have? Do you for example have a raw-water cooled heat exchanger or a fan-forced air radiator? At what temperature is the sea-water? What is rate of flow of the sea-water?