Fridge troubleshooting - advice requested

[chris in SG]

My Frigoboat front-loading fridge has a keel-cooler system. Recently the compressor started running continuously and the fridge was warm (negligible cooling) so I switched off the power, moved perishables into the freezer (separate system) and roughly one week later invited a technician onboard.

The technician asked me to switch on and a few minutes later the fridge started cooling. Aside from slight embarrassment, I was just thankful it worked.

In fact, it functioned normally for about one month after his visit. Now the same symptoms have re-occurred and I have just switched it off again - wondering if it 'needs a rest'. But seriously, this seems an unlikely intermittent fault. Does anyone recognize the symptoms or can anyone explain how the fridge was able to recover and function perfectly for a month without any action apart from resting it for one week?

[tkeithlu]

I'm supicious of moisture in the refrigerant, which is freezing up and then thawing. That would suggest a shorter "rest." If it's not that, I would be curious about a clog in the keel cooler or some other problem on the refrigerant side, because it does not sound like either an electrical problem or a failure of the compressor.

If none of that rings a bell, best wait for advice from someone with particular knowledge of these systems. Good luck with it.

[Coolerking]

Did he add any refrigerant to it?
If so it's possible the O rings are leaking at the fittings.
As mentioned above, moisture will/can also cause intermittent issues.

[B28_Majic]

Possible moisture or fouling on the keel cooler. When you say that the compressor is running, how can you tell, is it by amp draw or are you touching the compressor to see it its working?

[chris in SG]

Originally Posted by tkeithlu

I'm supicious of moisture in the refrigerant, which is freezing up and then thawing. That would suggest a shorter "rest." If it's not that, I would be curious about a clog in the keel cooler or some other problem on the refrigerant side, because it does not sound like either an electrical problem or a failure of the compressor.

This is very helpful (and the other replies reinforcing the diagnosis). I 'rested' it overnight and switched on again this morning and it is working fine, so this does seem likely to be moisture.

Presumably I need to find a different technician, who actually travels with a gas cylinder (the last one did not) and ask him to flush out and fully recharge.

Thanks for the feedback.

[RaymondR]

The noise you can hear when the fridge is running is only the cooling fan and the compressor may not be running and no cooling taking place even though it appears the fridge is running.

The problem could be just low battery voltage.

[skipgundlach]

There are extensive threads about Frigoboat issues in CF.

If yours is one of the older ones, the tiny filter-drier (about the size of a CO2 cartridge) is located too close to the compressor and never actually sucks out any moisture because it's too hot. The tiny capillary tube on the back of the evaporator can clog; a warm wet washcloth will sometimes allow it to free up.

A cure to the issue (or a help, assuming no other issues) would be to have a fan (tiny computer fan) blowing at the F-D to help keep it cool. Newer versions of FrigoBoat have larger RFDs and better positioning, so less likely to be that issue.

Check the other threads for hints on what might be happening in your system...

L8R

Skip

[Dougtiff]

From your description, i believe it's low voltage, [ i made that mistake, thinking it was low on gas], so you need to check the voltage, you can check for moisture , by applying a hot cloth to the evaporator line, where it exits the evaporator, lastly, pull a vacuum with a pump, while the box i.e. evaporator is warm [70 Deg., using a heat gun or lamp, pull down for say 4m hour's, then charge, it's easy to overcharge, the system only takes a few ounce's, frost line stops at the exit of line from compressor at box exit. [i'm in the Bay area if you need help].

[thunderhoof]

I think Dougtiff has it right. With the entire unit warm, room temp or above, pull a -20 psi vacuum and hold it for several hours. The elapsed time is necessary to get the water in the system to evaporate. Then, without breaking the vacuum recharge the unit making sure to add only gas, no liquid. I do this by placing the can of refrigerant flat on the sole, with the valve up. Then, with the compressor off, open the valve until the hissing stops, then close it. Run the compressor for a minute or so. then stop it and repeat the process. On my Frigiboat F35V I do this about 4 times, then run the unit for about twenty minutes. Check that the refrigerator is cooling and the frost line on the coolant return line is several feet from the compressor. If no frost line is visible, add a small amount of coolant and allow to run another half hour or so. Continue until you see a frost line but do not overcharge. Let the unit run all night and check the frost line again, If it is near the compressor, release a small amount of coolant.

[stormalong]

Most Danfos based refrigeration systems have a blinking LED that indicates what the problem might be. Different blinking pattern for different problems. The feature is built into the controller. If it doesn't have the LED you should be able to fit one.

For an intermittent problem that's where I'd start.

[Richard Kollmann]

If this is a keel cooler system with a Danfoss BD 35 or BD50 compressor install with the troubleshooting LED mentioned above the problem is easy to solve if electrical. If you need info on this $3 LED installation Email me and I will send you a PDF. It is unlikely LED will ever flash if compressor is running when compressor fails to run. It is most likely LED will flash a problem of low voltage spikes during start up or a fan is used to cool compressor, if fan is bad when it is drawing too much current, too much refrigerant will prevent compressor from running do to excessive amperage . Remember the compressor will only run if control electrical module is satisfied with amperage and voltage are correct.

If you checked the compressor to see if it is actually running and continuous hissing sound in box then check units amp draw to rule out poor keel cooler cooling do to material build up on its exterior.

It is unlikely the incorrectly installed filter in this system is the cause of problem at this tome. If you have been operating this unit for three to five years with compressor temperature to warm to to keep your hand, or this system has ever bin operated with boat out of water. I recommend installing a new oversize filter dryer in line between keel cooler and flow control capillar tube to prevent destroying complete system do to over heat contamination.

With an intermittent refrigerant flow as you describe moisture in system is easily detected by a hissing sound in refrigerated box when compressor is running and evaporator cooling is working. Then at times again when compressor is running and there is no cooling there will be no hissing sound in box as refrigerant flow is blocked temporally as moisture freezes and several minutes later melts.

[chris in SG]

Originally Posted by RaymondR

The noise you can hear when the fridge is running is only the cooling fan and the compressor may not be running and no cooling taking place even though it appears the fridge is running.

The problem could be just low battery voltage.

Thanks Raymond. The compressor is easily accessible and it's easy enough to confirm by touch that it is running continuously. Low voltage isn't an issue. But I appreciate your thoughts on this.

[Eder]

I have the same problem ....I have 2 danfoss systems. You definitely are having a moisture problem. This can arise from using the keel cooler out of the water as well as storing system in hot climates for extended periods...most likely not the o rings unless someone already has screwed around with your system



Go here 1st


https://coastalclimatecontrol.com/in...igeration.html


Do not let any tech mess with your system...!!! Serious.


Phone these guys up....order the premade dryer with quick connects about $129. 301-352-5738


When the temp gets more than 2 degrees above set temperature follow the video in the link I provided to fix an icing problem...no need to turn off fridge. Push the moisture thru to the dryer by warming with a hair dryer works. Once you hear the hissing noises you know the ice has been melted & fridge is working.


Repeat every time the fridge acts like this....I can do it in less than 5 minutes lol.


Fixed.


Once you open the system to try add refrigerant etc you're screwed and may need to replace cooling plates etc...no need to do it.

[Coolerking]

Originally Posted by Eder

I have the same problem ....I have 2 danfoss systems. You definitely are having a moisture problem. This can arise from using the keel cooler out of the water as well as storing system in hot climates for extended periods...most likely not the o rings unless someone already has screwed around with your system



Go here 1st


https://coastalclimatecontrol.com/in...igeration.html


Do not let any tech mess with your system...!!! Serious.


Phone these guys up....order the premade dryer with quick connects about $129. 301-352-5738


When the temp gets more than 2 degrees above set temperature follow the video in the link I provided to fix an icing problem...no need to turn off fridge. Push the moisture thru to the dryer by warming with a hair dryer works. Once you hear the hissing noises you know the ice has been melted & fridge is working.


Repeat every time the fridge acts like this....I can do it in less than 5 minutes lol.


Fixed.


Once you open the system to try add refrigerant etc you're screwed and may need to replace cooling plates etc...no need to do it.

If you have moisture in the circuit, and you continue to allow the system to operate, it will, mainly due to the acidification of the oil, destroy itself.
The o-rings are a consumable part, they ship the systems with spares because of this.
I have found most systems that have moisture got it by first leaking enough to cause the system to run in a vacuum on the suction side, drawing in the moisture, then they were merely topped off with 134a, or poorly/incompletely evacuated, and retained the contamination.

Listen to Richard. He knows what he is talking about.

[chris in SG]

Many thanks to Richard K and the other experienced contributors. It does seem clear from all the feedback that my problem is moisture in the system.

My current temporary solution is to switch off at night. I can't use a warm towel or hairdryer on the evaporator exit because the fridge is a front-loading cabinet which is officially described by Frigoboat as a "hidden evaporator larder fridge", with no freezer box type evaporator inside. The evaporator is enclosed between internal and external SS panels at the rear. I chose this design because I was also building a more efficient top-loading freezer. Stupidly, it didn't occur to me that this might be a maintenance nightmare waiting to happen.

This also means that the 'hissing' of a properly cooling system is difficult to hear, although in this climate there is a very fast appearance of condensation on the rear of the fridge interior when it IS working.

As for a more permanent solution, I'm hearing conflicting ideas here. I can avoid technicians if the addition of a "premade dryer with quick connects" is a likely solution, because this is a job I can do myself. I'm not going to attempt anything more ambitious..

Thanks again!