more Frigoboat fridge problems

[sv.antea]

I have a strange problem with my Frigiboat Capri35, aircooled, with 160F evaporator. I am fairly competent boat mechanic and have much experience installing refrigeration and airconditioning units on boats, but I never ventured into the refrigerant side of the systems. I installed the unit 5 years ago and it performed flawlesly untill about 6 months ago.
I have turned it off at that time to do some work on the icebox and when I turned it on a day later, it started to run normally, I could see the 4A current going in as usual, evaporator was frosting over, but after few hours I found the ice box creeping up to room temperature. High and low pressure lines at the compressor were warm, about same as the compressor, which, from the faint vibration was still running, but now drawing only 2A. I thought the compressor was toast, but I kept turning it off and on (after 20 minutes). I checked electrical connections, all good, plenty of voltage 13.6V. Same thing, the compressor would quiet down after 10-15 minutes, draw half the current and provide no cooling. Then after third or fourth try it stayed running and worked as usual for the next couple of months.
At that time I still had the mechanical thermostat, but had a problem with it as the slightest brush against it would alway turn it to lower temp. setting. Had to tape it over with masking tape to keep it set. As I was about to install same Frigoboat set up on my friends boat, I added extra Guardian digital thermostat to the parts order and replaced the mechanical thermostat. Now I will be able to use the diagnostic fleshing LED to pinpoint the problem if it happens again.
Same thing happened after I restarted the unit. The fridge would run for a bit, then, compressor still running, the evaporator plate would get to the icebox temperature. Puzzled, but armed with experience, I turned the unit on and off, untill it stayed running.
The new digital the thermostat does a marvelous job keeping the ice box between 40 and 42F, but now the evaporator gets frosted up. Takes a month or so, but eventuall I have to turn the fridge off to defrost it. Each time it has few false starts before drawing the box down to 40F. Yesterday it wouldn't stay working even after six attempts. And the diagnostic LED is not blinking.
Any ideas, please help.

[ColdEH]

Im no expert , but sounds like a low voltage problem. Richard Kollman just commented on a very similar problem on another thread. The voltage drop on startup is so short that you can not see it on a multi meter, but enough to set the controller to a restart mode . Try running a whole new wire directly to the battery bank , make sure it is a good size for the distance and current.

Regards

[sv.antea]

Thanks Typhoon, I am very thorough installing elctrical systems, while I haven't check the voltage at the unit, the problem persisted through a complete rewire when I converted to the Guardian digital thermostat. Besides, a voltage drop would likely cause the compressor not to start. In my case it starts, provided I leave it off for 10 minutes or more, bringing the Icebox temperature down rapidly, initially drawing 7.5A and over a period of 4 minutes, taper down to the healthy 4.3A. It holds that for 10-15 minutes, but then keeps running without cooling and the draw gets to steady 2A. The error LED should come on if the voltage was too low as well.
As I said, I m good with things electrical, but stayed away from the Freon and the gauges. Let me ask this to the experts here. Wouldn't blockage in the freon circuit casue higher current to the compressor? Bit of ice forming in the capilary? If I restart the unit too soon (less than 15 minutes after shut down), I see the dreadded 2A draw, no cooling, no familar hissing around the evaporator plate. Makes me thing ice blockage. I haven't disturbed the freon circuit since installed though...The little yellow icon in the upper left hand corner of the Guardian thermostat stays on, too, which seems to confirm the compressor is running. Still no diagnostic LED flashes.

[a64pilot]

OK, until someone smarter than me comes along and gives a better answer, will a partially blocked evaporator orifice do this?
I read your last post after I posed this, I don't think you can get ice inside of a refrigeration circuit ( no moisture), but I have seen other systems suffer from a small particle blocking the orifice, maybe dirt, maybe a small piece of metal, I don't know.
Does your system have a drier? Driers also function as filters I believe.

[sv.antea]

OK, guess I am SOL this time, turned it of and back on after various intervals 10 to 40 minutes. It is not going to wake up. Did check the voltage at the electronic module. I doesn't budge from what the house bank reads when the system ramps on, presently with the 40A ProNautic in bulk it's at 14.7V. What with the digital thermostat using about 0.2A, the fan about 0.7 (I am guessing here), the compressor is humming and drawing less than 1.5A. Could it be that the compressor is not turning, just humming from small supplied AC and the fault is in the electronic controller? Again, no fault display, no red blinking LCD.
Any of you "license to chill" types have any suggestions what to check next?

[sv.antea]

ok, so no one has any ideas, nobody's writing, so I'll sit myself down and write myself a letter.
Yesterday I put couple of bags of ice in the ice box and the system settled itsef in a definite pattern. The temperature with the ice bags holds around 35.5 deg F. I flip on the breaker, the compressor starts, the current ramps up to 6A then slowly down to 4.5A. The ice box temperature starts dropping but the current continues to drop as wll. Within 10 minutes, the compressor still humming, although much quieter now, the temperature is down to 33.8F but climbing, current is down to 1.5A, so I turn the power off.

Now, I have read the threads on CF and the troubleshooting guide on the Frigoboat website, but before I go twisting the capilary tube, tapping with a screwdriver, or get prefessional help, I'd like get a clue what might be the problem. The symptoms don't quite fit the problems I have read about.
Again, the fridege performed as usual until two days ago, the speed set for 60% on 40% off pattern. Three times within the past 6 months I had to turn it off and back on few times after power was turned off for couple of hours to get it to stay working. But it always resumed normal operation until now.

[Ndavies]

Interesting problem and some interesting thoughts and advice. Like you, I am no refrigeration or A/C expert - but I have fixed and replaced a few. My first thought is voltage - you will not be able to measure instantaneous start voltage with a typical meter, so the only thing to do is check every connection - twice! or try heavy gauge jumpers directly to the battery.

Is it a variable speed compressor? Some compressors are, and can run variable speed if using a digital thermostat. What type is it? Danfoss? - if so, search Google, there is information out there on how to use in variable speed or fixed speed mode. If its variable speed, I would check the configuration and try it in single speed mode. If all else fails, I would try adding a little Freon - but a very small amount, and see if that makes a difference. Good luck, and please report back!

Neil

[onestepcsy37]

Go here first.

Kollmann Marine

Richard Kollmann is maybe the best boat refrigerator guy around. He's retired now - used to have the best boat refrigeration shop in Fort Lauderdale - but still keeps up his website and often answers questions here. Suprised he hasn't come on your question yet but maybe he's on vacation. Oddly enough, even retired people go on vacation.

His site is full of useful information. If you have a bad control module - and you may have one - he has some kind of a "loaner" program to help you diagnose your problem.

[mikereed100]

I have found the folks at Great Water, where I bought my Frigoboat, be very helpful and knowledgeable. It would be very worthwhile to give them a call. Frigoboats have had issues with blockages due to contaminants and ice in the lines and now sell a filter that you can put inline to address this.

https://great-water.com/products/fri...-filter-drier/

[Moontide]

Had a similar problem with an air cooled danfoss compressor last year while in Mexico. Turned out it was low on freon. Would run but never get as cold as it used to. First guy added freon and it seemed to work for a little while, then problem returned. Of course by then we were further down the coast. Second guy checked and turns out it was now overfilled with freon. He took a vacumn pump and extracted all the freon. Left it for 10 minutes to make sure no leak in the system, then refilled it. Has worked great since then.

Second guy told me that you should never add freon to an existing system. Need to evacuate all the old and then refill it.

At least now I am a better supervisor of refrigeration repairs. :-)

[sv.antea]

Thanks for all the replys. I do not suspect the power supply. The compressor ramps up on this Danfoss model anyway. I monitored the voltage and it doesn't dip. Also, if I give it 20 minutes or so, it always starts and starts cooling. There is a diagnostic LED on the Guardian digital thermostat, that would confirm low voltage. It works, I faked poor connection and it lit up.
Low freon occured to me, but I had the same problem three times in the past 6 months, but until now it always came to it's senses and started to work again. Could it be the inverter that supplys the compressor with variable frequency alternating current? I think it's refered to as "electronic module" If the voltage fades out due to some internal component that heats up, that would explain the current fade and the fade of the humming of the compressor. Externally it stays cool, the diagnostic LED should blink an error code to indicate when it overheats.

[senormechanico]

It sounds like an ice blockage in the refrigerant to me.

[sv.antea]

If I assume ice forms with a great regularity, would the current draw gradually decrease as the the freon flow is restricted?

[sv.antea]

I almost concluded that the problem was low refrigerant, but after reading the Frigoboat troubleshooting and recharging guidlines, neither slight or sever undercharge symptoms as described match the symptoms in my system. In both cases, the evaporator sound should be constant.
Here upon start up, the evaporator stays quiet for 20-30 seconds, then little squeeks start at irregular intervals, then become more frequent. After about 90 seconds, it sounds like a distant steam locomotive for a few seconds. hiss and pause beat of about 1second period. Later the pauses go away, hissing is continuous but a squeeking sound is added, sounds like an old AM radio tuning over distant stations. The tone goes up and down. At this point, frost starts forming on the evaporator. Then at about 4 - 8 minutes, the hiss becomes interrupted again, as if some valve opened only when adequate pressure builds up. The noise volume goes down and eventually the hissing stops, the frost melts.
The freon connectors have never been opened since installation 5 years ago. Could it be moisture and ice forming at the capilary? Could the ice blockage, maybe combined with some debris restriction produce such regular and repeatable symptoms? Combination of above and some freon shortage?

[mikereed100]

Originally Posted by sv.antea

. Could it be moisture and ice forming at the capilary? Could the ice blockage, maybe combined with some debris restriction produce such regular and repeatable symptoms? Combination of above and some freon shortage?

Several of us have suggested this already. Not sure what you are waiting for? The following is from the Great Water website that I linked to previously:

http://great-water.com/store/PDF/fil...and_Repair.pdf

Intermittent Blockage of the Cap Tube – Diagnosis and Repair

If you have been experiencing intermittent problems whereby the compressor runs but no cooling
takes place, there is a possibility that you have a small piece of debris in the system that is
intermittently blocking the entrance to the capillary tube (cap tube). The classic symptom of this
condition is that the temperature in the box starts rising, but the compressor continues to run.
Turning off and restoring power to the system after a short rest may restore the system to normal
running again, but some time in the future the problem will usually return, although this could be
minutes, hours, days, weeks, months or even years later. Quite often this condition appears after a
rough or boisterous passage.
The cap tube looks like a piece of wire, but in fact is a small tube with a micro-bore down the
center, and this separates the high and low pressure sides of the system. Any small piece of debris
(usually introduced during installation) that finds its way to the end of the cap tube can block it, and
so no refrigerant flows even though the compressor is running. Turn the system off, and the
pressures equalize which releases the debris and unblocks the end of the cap tube. It's just a
matter of luck as to where the offending piece of junk sits in the rest period, and whether or not it
causes a blockage on the next cycle. With the boat at rest in a marina, etc., the problem may not
surface again until you encounter some heavy weather, and then the debris is disturbed from its
resting place to cause havoc and mayhem again. Very frustrating!
So what is the remedy? Evacuating the system with a vacuum pump will simply relocate the
debris, and this may prove to be all that is required, but the only true cure is to replace the
evaporator and install a filter-drier in the liquid line. The filter-drier will stop any more debris getting
to the end of the cap tube (the cap tube is integral with the tubing attached to the evaporator). But
there is something else that is worth trying, as it has worked on numerous occasions. You will need
to locate the section of tubing that incorporates the end of the cap tube and orientate that section
vertically in the hope that the debris has enough mass to be trapped somewhere and cannot get to
the end of the cap tube. The cap tube is run inside the suction tube, and if you follow the tubing
back from the evaporator for approx. 9ft you will come across a section where the cap tube exits
from inside the suction line. It then takes a few turns around the suction line before disappearing
inside a slightly larger tube and then on to a coupling, and it is this area we want to focus on. Once
the cap tube enters the slightly larger tube it extends inside it for a few inches, maybe three or four,
(it depends on who fabricated it) and so it is this section that needs to be fashioned so that it is
vertical. Either way up should work, but I suggest you try first with the cap tube entering from the
top, and if that doesn't work try the other way up. A few sharp taps on the tubing with a screwdriver
handle when vertical will help to settle the debris. If neither method is successful there is no
alternative but to replace the evaporator and add a filter/drier.