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Old 06-10-2024, 09:29   #1
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Frigoboat K50F not cooling

I have a keel cooled Frigoboat K50F refrigerator that worked normally with the thermostat on anything up to the maximum cool setting but then started to quit. A workaround was to limit the fridge to low settings only. What happened was the compressor motor kicked off with a 7amp draw (12volts) then continued a cycle of reduced current draw until the thermostat opened, when on a low setting. When the thermostat closed again a successful repeat cycle followed. On a high setting it never "got there" with the slow part of the cycle not maintaining the initial evaporator frosting, allowing it to melt. Now it starts with only an initial 5A draw then continually maintains its slow cycle with no cooling at all. I replaced the controller but it behaves the same.

It's looking like the system needs re-charging but I would be grateful for any advice to confirm this or otherwise. The boat is 22 years old, does refrigerant deteriorate over time or only if there's a leak?
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Old 06-10-2024, 10:07   #2
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Re: Frigoboat K50F not cooling

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Originally Posted by RobandMarj View Post
I have a keel cooled Frigoboat K50F refrigerator that worked normally with the thermostat on anything up to the maximum cool setting but then started to quit. A workaround was to limit the fridge to low settings only. What happened was the compressor motor kicked off with a 7amp draw (12volts) then continued a cycle of reduced current draw until the thermostat opened, when on a low setting. When the thermostat closed again a successful repeat cycle followed. On a high setting it never "got there" with the slow part of the cycle not maintaining the initial evaporator frosting, allowing it to melt. Now it starts with only an initial 5A draw then continually maintains its slow cycle with no cooling at all. I replaced the controller but it behaves the same.

It's looking like the system needs re-charging but I would be grateful for any advice to confirm this or otherwise. The boat is 22 years old, does refrigerant deteriorate over time or only if there's a leak?
Frigoboat has quick connect fittings that require O-ring replacement every 5 years. It comes with spares and also the caps to cap it off during shipping have the same O rings.

Also, the keel coolers tend to be problematic with releasing particles into the refrigerant which clog up the evaporator tube.
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Old 06-10-2024, 12:03   #3
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Re: Frigoboat K50F not cooling

Thank you kindly for your prompt reply. I guess I need to replace the o-rings, clear out the system and recharge. As a newbie I'll weigh up whether to buy the kit to do the job myself or call in a refrigeration specialist. Apparently disposal of refrigerants is illegal in the UK unless done by a licensed operative.
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Old 06-10-2024, 21:04   #4
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Re: Frigoboat K50F not cooling

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Thank you kindly for your prompt reply. I guess I need to replace the o-rings, clear out the system and recharge. As a newbie I'll weigh up whether to buy the kit to do the job myself or call in a refrigeration specialist. Apparently disposal of refrigerants is illegal in the UK unless done by a licensed operative.
You don’t need to evacuate the system to replace the O-rings, just switch it off and undo the connections with two wrenches (you call them spanners, right? )
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Old 07-10-2024, 01:05   #5
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Re: Frigoboat K50F not cooling

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Also, the keel coolers tend to be problematic with releasing particles into the refrigerant which clog up the evaporator tube.



Is this a general statement about keel coolers or specific to Frigoboat? I have 2 of these and replaced one due to external damage. There is a copper tube containing the refrigerant that is fully encapsulated by sintered bronze block. How could this release particles into the system?
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Old 07-10-2024, 06:42   #6
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Re: Frigoboat K50F not cooling

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Is this a general statement about keel coolers or specific to Frigoboat? I have 2 of these and replaced one due to external damage. There is a copper tube containing the refrigerant that is fully encapsulated by sintered bronze block. How could this release particles into the system?
It’s what happens with Frigoboat units. Maybe they fixed the issue and my info is outdated but I didn’t hear that…

There has been speculation on where these particles come from but nothing more than that. I think it’s from the production process. What is sure is that they are there and plug up the capillary tube. I fixed my installation a number of times by using a vacuum pump to create reverse flow, then install a large filter/dryer between keel cooler and evaporator.
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Old 07-10-2024, 07:54   #7
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Re: Frigoboat K50F not cooling

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It’s what happens with Frigoboat units. Maybe they fixed the issue and my info is outdated but I didn’t hear that…

There has been speculation on where these particles come from but nothing more than that. I think it’s from the production process. What is sure is that they are there and plug up the capillary tube. I fixed my installation a number of times by using a vacuum pump to create reverse flow, then install a large filter/dryer between keel cooler and evaporator.

Agree the capillary blockage is quite common but this is next to the evaporator plate and is due to oil in the system. We cut one open to see. It occurs on the air cooled units as well. The standard bullet style driers are inadequate. I have replaced mine with large AC, beer can size driers, 15 years ago never had a issue since.
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Old 10-10-2024, 10:53   #8
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Re: Frigoboat K50F not cooling

My K50 keel cooled fridge has been running for almost 10 years with not a single problem. You should get advice from people that actually have a K50 keel cooled fridge.
I had to wire mine direct to the house bank. Fused properly. When we would flush the electric head the water pump and head macerator would turn on and the fridge would see a voltage drop and shut off. When voltage was back up it turns back on. Direct to the batteries this doesn't happen
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Old 10-10-2024, 12:08   #9
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Re: Frigoboat K50F not cooling

I always have a bit of concern about the little 12V units that have water cooling.
They seem to work best when the water temp is neither not very cold nor hot, as without receivers and using cap tubes they have no ability to either provide excess refrigerant flow to the evaporator or retard flow/store refrigerant.
If operated in colder water the refrigerant can become sub-cooled to the point where it fails to fully expand in the evaporator, this causes a reduction in the ability of the refrigerant to absorb heat.
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Old 10-10-2024, 12:40   #10
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Re: Frigoboat K50F not cooling

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I always have a bit of concern about the little 12V units that have water cooling.
They seem to work best when the water temp is neither not very cold nor hot, as without receivers and using cap tubes they have no ability to either provide excess refrigerant flow to the evaporator or retard flow/store refrigerant.
If operated in colder water the refrigerant can become sub-cooled to the point where it fails to fully expand in the evaporator, this causes a reduction in the ability of the refrigerant to absorb heat.



My 12v units are 22 years old, replaced one keel cooler due to external damage but was still working. Ran constantly for 15 years with a break of 10 months. Mostly in the tropics but also in UK. Freezer sits at -20C drawing 20A/day and is good for keeping Magnum ice creams, the fridge is equally efficient drawing a little more than the freezer.
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Old 10-10-2024, 13:06   #11
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Re: Frigoboat K50F not cooling

^ Understand what you say.
I perhaps could have been clearer.
I was only trying to make the point that without the ability to modulate water flow the operational efficiency of water-cooled units take a big swing when going from 30C water in Mexico to 1C in Alaska.
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Old 10-10-2024, 18:17   #12
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Re: Frigoboat K50F not cooling

Here’s another tip: if you have the keelcooler option, you can get an air cooled condenser and put it in series, giving you a choice on which one to use. When hauled out, you can’t use the keelcooler but you can simply switch to the other one.

Anyway, I think I may still have one of those as well as maybe a big filter/drier, both with quick connects for easy install. If you need any of that and are in the US, let me know and I’ll see what I still have…
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