more Frigoboat fridge problems

[sv.antea]

Thanks Mikereed, I have read the opinions and the the post you coppied. In fact I read that post 6 months ago when I encountered the proble first time. Then the problem was intermittent, so the conclusions had more merrit, but I chose to leave well enough alone.
I have also read a thread, where same problems were casued by faulty controller module.
So before I dive in and start taking things appart, I was hoping someone would suggest a test or check that will confirm I will need to replace the evaporator and add a drier and eliminate the defective controller idea. How would moisture get in after 4 years of undisturbed system? Debris, I can see that. But normal cycling never caused any problems. It was only when left turned off untill the box reached room temperature that the condition appeared. Several times it resumed normal operation before after few on/offs, but not this time. Wouldn't the electronic module shut down the compressor if the capilary is blocked? If ice blockage is slowly formed around the debris blocking the capilary, wouldn't the current go up rather than slowly decrease. Wouldn't my Guardian digital thermostat diagnostic LED indicate the compressor is stopped?
Replacing the electronic module is cheaper and, on my boat, vastly easier to do than replacing the evaporator. So I am in denial, I guess. I seems also, that the length of time the colling lasts is proportional to the time off. My fridge had been cycling 14 on 12 minutes off, which could mask the problem in the past as the thermostat would shut the compressor off before the current decline. I'd really like to avoid replacing the evaporator, or calling a refrigeration pro, mostly for financial reason.

[mikereed100]

I understand the reluctance to call a refrigeration professional as that term is very broad (to be kind). I also understand your reluctance to replace the evaporator if you are not sure that's the problem. If you are lucky, Richard Kollman will see this thread and chime in with much better advice than the rest of us can provide, but until then why not give Frigoboat a call? Tech support at Great Water is very good and they should be able to answer your questions.

[rveldman1]

Good morning. I don't know if you've solved your problem yet, but I had a similar problem with my refrigeration unit. When plugged into the dock, I had 13.6 volts and the unit would turn on run for 15 to 20 seconds and turn off . After much ado, , I found my battery was no good. I replaced the battery that was powering the unit, and all my problems were solved.

[Richard Kollmann]

SV antea, First question, does your Capre 35 compressor have the $3 troubleshooting LED installed on Danfoss module terminals small+ and terminal D?

If compressor does not run trouble LED will send a flashing code as long as thermostat circuit is good. One flash every 4 seconds means a problem with boats electrical power grid or circuit breaker or wire terminal corrosion. Two flashes, fan is drawing more than ½ amp. 3,4,5 and 6 flashing code would indicant a strange or high amperage.

Your question would blocked capillary tube stop compressor? Compressor should keep running unless there is too much refrigerant in system.

Moisture in refrigerant freezing in cap tube is easy to determine by evaporator temperature remaining at 33 to 37 degrees and covered with cold condensation and no frost. A second method used to determine ice blockage of cap tube is by listening inside box for the hissing noise of refrigerant that stops when ice forms and as ice melts refrigerant hissing sound begins again briefly until it freezes again.

Frigoboat keel cooler systems are very unfriendly when operated in hot climates I believe do to poor compressor cooling.

Here are parts of my standard troubleshooting steps. Do not overlook the fan if one of its 10 internal transistors is bad or its bearings are worn module will not let compressor start although fan will still run on 12 volts.

Three and Four pin Danfoss BD troubleshooting

If your refrigeration unit is over 10 years old and has a Danfoss BD 2 or BD2.5 or BD3 compressor then it has the older discontinued electronic 4 pin module.
Troubleshooting Danfoss compressors with 3 and 4 pin modules will consists of the following steps:

1. All of these compressors have a 4 pin module connector and their modules contain an external fuse. If this fuse is blown there are two reasons why either power wires to module are reversed or module has an internal failure.

2. Check to see that there is actually power at the refrigerator control module.

3. Place jumper wire across thermostat terminals on electronic module, Compressor still does not run go next step.

4. Disconnect black fan wire from electronic module, Compressor runs, replace fan. Compressor still does not run after fan ground wire is disconnected, go to next step.

5. Run correct size and correct polarity jumper wires direct from a fully charged battery in order to bypass all boat’s wiring. Volt meter readings are of no value when looking for voltage spikes. Compressor still does not run electronic module needs to be removed and tested on another unit. If there are no other units available to test your module on I will test all 12 volt Danfoss control modules free except for BD80 compressor modules. Small 12/24 volt boat refrigeration using Danfoss compressors manufactured after 1996 will have a BD 35 or BD 50 variable speed compressor with a troubleshooting computer chip built into their control module. This circuit makes them easier to find troubled area if compressor fails to run. If your unit does not have this $2 LED install one, as it could save you a lot of money later. Without the LED on these new units troubleshooting will be the same as earlier 4 pin Danfoss BD compressors.

If after running the above checks and you suspect module you can mail it to me an I will test it on a refrigeration unit you only pay shipping .

My advice is free so do not call an engineer or technician unless you want real trouble. Ninety percent of the time even refrigeration experts will cause more damage on a keel cooler system than you already have.

[sv.antea]

OK, thanks for all your help. I will save the reply by Richard Kollmann, The fridge is not fixed yet, but I have isolated the problem. As many of you suggested, it is the expansion orfice getting plugged up with ice, moisture in the freon. Seemed like the most likely problem from the start, but
a/ I don't have gauges and evacuating, looking for debris, flushing and refilling sounded pretty scary
b/ didn't want to do all that and find out that it was something simpler to fix
c/ I was waiting for someone to confirm, that when the capilary gets plugged up, the compressor current goes down, not up as I expected.
In the end, the test was simple. A local marine refrigeration technician, when I finally got hold of him, suggested using hair dryer to heat up the spot on the evaporator where the gas expansion takes place, the orfice. So, after running the fridge for 10 minutes, when the current started ramping down and the hissing noise quit, I used the hair dryer untill the orfice area of the evaporator was just warm to the touch. (see attached detail of Frigiboat evaporator 160F) The hissing returned and the current had gone back to normal. Of course, that hasn't solved the problem, just confirmed the diagnosis. It just froze up again, but now I know there is definitelly a transition from steady hiss to hiss with whistled and chirps as the orfice begins to close up, accompanied by current reduction. I think I have enough material on solutions to this, I just need to read up.

[Richard Kollmann]

Good luck but I think you are on the wrong track. I always recommend non destructive testing to confirm the problem first before tampering with refrigerant by even connecting gauges. How did moisture get in system if no one has ever tampered with refrigerant? By increasing system temperature you did create added flow but only for a short time.

The typical Frigoboat keel cooler system problems begin with hot compressor high pressure gas and line connector O ring leaks. Next comes overcharging of refrigerant increasing heat even more and thickening of oil. Last step is cap tube restriction and replace one or two evaporator assemblies. After spending one or two thousand dollars complete system replacement is final fix.

[mikereed100]

Richard,

As the owner of a Frigoboat keel-cooled unit you've got me nervous. Could all of the above be avoided by keeping the compressor cool using an auxiliary fan and replacing the o-rings on a regular basis?

[skipmac]

Originally Posted by mikereed100

Richard,

As the owner of a Frigoboat keel-cooled unit you've got me nervous. Could all of the above be avoided by keeping the compressor cool using an auxiliary fan and replacing the o-rings on a regular basis?

I have a similar concern and question. My Frigoboat is air cooled but from what I have read, there is still a potential problem with leaks around the O-rings over time.

I guess the answer is to periodically replace the O-rings? But how often?

Also are these connectors totally idiot proof, that is if/when I disconnect the refrigerant lines they will completely seal, zero refrigerant loss and zero chance of moisture or contaminants leaking into the system? The last question of course assumes I am being careful to keep the ends clean and protected while swapping the O-rings.

[sv.antea]

- Richard, I don't understand the part about being on the wrong track. I have warmed up the orfice and noted the freon flow resumed temporarily to eliminate the possibility that the module is defective and cause the compressor to slow down. Is it that you ment it was unnecesary? I am learning here. The Guardian thermostat has the diagnostic LED and it never flashed, so it should have told me that the compressor operates at adequate RPMs. Then again, I had never seen it come on, so to make sure it worked, I intentionally created a poor connection, and, voilà, it blinked as advertised.
It is an air cooled unit, and the freon circuit has never been disturbed since very carefull installation 5 years ago. That brings back the question of O-rings. Replace or not? Again, the unit now always cools untill most of the 160F evaporator is frosted over, the hiss more or less steady, much like it had always been, power draw 4.5A, as it had always been, untill 5 - 10 minutes later the hiss and the current peter out. The compressor never stops.
Now, I am assuming that is caused by moisture in the system freezing up the orfice. I am proposing to evacuate, change the O-rings, put a vac pump on it for 4-6 hrs, then refill with just enough freon little bit at a time untill it frosts up 95% of the evaporator, but not too much so it doesn't frost up the return tube. Local shop mentioned ~4 oz of freon. Somewhere I read something about back flushing, nitrogen and such - any of that is advisable? My friend who does marine refrigeration suggests I forego the O ring replacement. What would be your recomendations?
Someone here asked about replacing the O-ring regularly. From what I read I think that may be asking for trouble. Carying spare sets may be a good idea, the new units come with a baggie of the O-rings taped to the comoressor. As for cooling the compressor, it should stay cool enough from the returning freon once the temp in the box settles down to the required temperature. Here is where the correct amount of freon comes in as well.

[Richard Kollmann]

Skipmac’s is Frigoboat’s fan air cooled system. A conventional refrigerant system begins with a gas vapor compressor moving high pressure hot gas of around 194 degrees F directly into a condenser where the process heat is removed and vapor is condensed into a liquid at somewhere around 115 degrees F. in a warm tropical climate. Liquid leaving condensing unit passes through a Refrigerant filter/dryer before interring liquid line towards the capillary tube refrigerant flow controller. At the end of capillary tube liquid refrigerant changes phase to gas vapor inside evaporator where heat is removed. Refrigerant leaving evaporator retains enough moderate cool temperature to cool compressor completing the closed circuit loop. O ring seal leaks are less likely to leak on the conventional systems because they are not exposed to damaging heat.

What makes Mike’s Keel cooler design non conventional is the filter dryer is located too near the warm compressor in return line from evaporator. Correct location of filter is in liquid line protecting cap tube orifice from blockages. There are many reasons why O ring seals leak with one additional factor on this keel cooler model is the high temperature liquid line connector O rings between compressor and keel cooler are exposed to extreme heat.


My best guess is that if the box being refrigerated is no larger than 6 cu ft and boat is not operated for long periods of time in tropical weather Frigoboat’s keel cooler system will perform well. Most of these failures I believe can be contributed to excessive compressor/oil over heating. I like to think if you can not keep your hand on compressor dome it is running too hot over 135 degrees F. Only Frigoboat may know what causes compressor oil to be contaminated enough to restrict refrigerant flow through cap tube. As far as I know Frigoboat’s fixes listed on their web site are just postponing the eventual removal of complete system. I also can not see justification for routine replacement of O ring line connector seals.

[skipmac]

Hi Richard,

Once again thanks. As always a wealth of knowledge.


Skip

[Richard Kollmann]

SV antea,

Because of Frigoboats history of cap tube blockages I tried not to jump to the conclusion that your unit has a serious problem. There are two possibilities for the condition you describe. Evaporator does get covered with frost then compressor keeps running and cooling stops. There are two reasons for this condition moisture in refrigerant oil and contaminated oil.

I tried to stop you from going down the path of moisture until it was truly confirmed by monitoring refrigerant sound and seeing the evaporator remains for several minutes or hours at a temperature just above freezing and covered with condensation and no frost. With moisture in this small system it freezes and melts to maintain an temperature just above freezing. If it is confirmed to be moisture it will be extremely difficult to remove from the new POE ester oil even with super deep evacuation.

[sv.antea]

Sorry, Richard, haven't been alerted to your post, found it just now. Thanks. I haven't done anything about it and I store my leftovers in friends boat, where I just installed identical set up.
The symptoms are fortunately very constant. If I turn the power on (it's been off for days and the fridge is at room temperature, which here in Florida is ~84deg. The compressor starts, current ramps up to ~6A. Hissing in the condensor starts after 40 seconds and the current tapers of to 4.3A, about what it always did. The plate gets evenly frosted over, the hissing continues for 6-11 minutes, than its starts sounding little strangled with whistles and squeeks at which point the current starts tapering off and the hissing diminishes. in the end, the hissing stops completely and the current drops to ~1.2A. And stays there. The plate frost slowly melts. The compressor never stops. My Guardian thermostat has the diagnostic LED, it never flashes. It works, I tested it. As far as I know, the plate never refrosted again and the current never goes up, untill I turn the power off for at least half hour.
The system, was never disturbed, gauges were never connected. I am waiting for replacement O-rings, I'll either borrow or buy a vac pump, evacuate and add freon myself according to the published Frigoboat guidelines. From your comments, I wonder if that may not fix my problem.
Question: will I be able to deep evacuate the sustem with a under $100 vac pump given time and patience, or do I haver to borrow a professional model.
If it was just moisture, logically, the system should eventually start functioning again when the ice blockage melts, repeating the cycle. At one point I have took a hairdrier to the orfice area of the plate (see picture few posts back) and got the freon to flow again for few minutes. Thanks a lot for your advice, and can I have some more?

[sv.antea]

Update, more testing results:
Previously I have not let the compressor run too long with the orfice blocked, thought it may damage it, but reading Richard's post I just did. I came back on board about 40 minutes after turning it on and the evaporator was hissing. I was lucky. Withing a minute, the hissing stopped. I noticed the compressor got hot, too hot to leave hand on it. Makes sense, no cool freon coming back to cool it. Ha, I am learning. The frosting on the plate got quickly soft, still no hissing, so I rubbed the orfice area of the plate with my fingers to warm it up and, lo and behold, it started to hiss. The ice plug has melted.
So, do you think I will have luck evacuating it and refilling? Do I need an expensive pump? Does the price just determine how quickly it can be done? What are minimal specs for a pump that can do the job, if time is not of essence?

[Richard Kollmann]

If test showed frost cover of evaporator when warm without adding heat and when hissing stopped and started hissing again every few minutes and evaporator plate kept cold condensation on it surface. I would first consider ice blockage requiring deep vacuuming. Sometimes it is difficult to determine Frigoboat’s keel cooler oil thickening problems restricting refrigerant flow from moisture in refrigerant.

Methods used for the last 50 years to remove moisture from these small capillary tube systems will not work with 134a refrigerant and Ester oil. With 70 degrees F ambient air surrounding system 2 to 4 hours on pump is not going to cause this POE oil to give up moisture. Average refrigerant low pressure gauges read vacuum down to 30 inches. The actual vacuum is unknown with this type gauge. As long as vacuum pump will reach 100 micron in hours 3 and 4 of the process I have been successful in getting moisture out. To be doubly sure system is completely dehydrated I raise temperature of all components containing refrigerant to 100 degrees F.

All refrigerant vacuum pumps are rated in CFM and ability to reach a very low vacuum most say 25 to 50 microns. One inch of gauge vacuum is equal to 12,000 microns. Atmosphere pressure is 14.7 psi to remove it from refrigerant it would be around 30 inches of vacuum or more than 360,000 micron. If your $100 pump is rated at to drop pressure to under 100 microns it will do the job, Low Cfm capacity is not a problem on this small system.

If you are unable to resolve this refrigerant flow restriction trouble by a good attempt in dehydration all that is left I am afraid is to replace complete system. I have only seen two non Frigoboat keel cooler systems powered by Dandfoss BD compressors with 25 years in service with oil too thick to flow through cap tube orifices. I believe five years in a tropic climate puts a keel cooler system at risk of cap tube restriction especially when installed in a large heat load box or when demanding low box temperatures.