Referigeration help

[Gene T]

I have a Frigoboat refrigeration system. It is working now and cycles on and off as it should. However twice now it has quit cooling. The compressor is running but it is not cooling. I have been able to turn it off for and hour and back on and it works again. I runs for months with no problems then quits. It is probably a 1998 unit. Unknown when it was last worked on as I have had the boat for a year now. R134a

Hoping there are some refrigeration gurus on the list.

The beast:


Thanks

Gene

[JohnRPollard]

Hi Gene,

We have a Frigoboat unit too, but ours is keel-cooled. Yours appears to be air-cooled, no?

Are you certain that the compressor is running, or could it just be the cooling/radiator fan?

[Gene T]

Air cooled. Compressor running? Good question as the fan make more noise than the compressor, but I checked the current draw and (my impression was) it was drawing about about 3.5 amps. The fan should only be about half an amp. So I am guessing the compressor was running, however next time it does it I will check it out closer.

Thanks
Gene

[JohnRPollard]

Gene,

I'm not a refrigeration guru by any means. I do know that we can hear our compressor cycling, but only just barely -- it is VERY quiet. With a cabin fan running, we'd never hear it.

The current draw would be the biggest indicator -- and your 3.5 amp draw is right on spec for the smaller Danfoss compressors that Frigoboat currently uses.

The good news is, it sounds like your unit works, but is just experiencing a gremlin. Hopefully someone else will chime in with some suggestions for where to check.

[svHyLyte]

Gene--

You might want to click over to Richard Kollman's site (the Gruru of Chill) and speak with him but it may simply be a case of low refrigerant. We had a (roughly) similar problem with our Frigoboat unit a number of years ago and low coolant was the issue. The good news is that the units are quite robust. Ours lasted upwards of 20 years (although we are now in the process of replacing it).

FWIW...

[deniseO30]

Gene,
the condenser fan motor would be the first and most likely part to ck. they have a way of running all the time and quitting after an off cycle. The amps on the fan motor would be very very low. You could also ck and make sure the condenser coil is clean and the fins have good air flow. You should hear refrigerant gurgling in the evaporator when the system is running also.. the correct temp check would be air coming off the condensor fan would be about 10-15 degrees warmer then the air going in.

[Omatako]

Gene, if it works OK sometimes and not at all other times and the compressor appears to be running, I would suggest that it may be the expansion valve that is messing you about. They are not a dynamic component but they do sometimes cause fridges to come and go. When next the fridge doesn't cool, use a drift on one side of the valve and give it a light whack (I think it's the valve on the left side of the picture). It may start cooling.

Having said that, I think 3.5 amps is quite light for an old-generation unit. Maybe that's just the fan? I have an old-generation fridge on my boat similar to yours (that is getting thrown out soon) and when it runs it draws 10 to 12 amps.

[JimsCAL]

Based on it happening only occasionally and fine when you turn it off for an hour, I suspect the compressor high pressure cutout may have tripped. Make sure the condensor airflow is not restricted, coils and fins are clean, fan running well, etc.

[Zanshin]

This could be a compressor stall. I installed the Frigoboat SSC devices and once saw the flashing light for a compressor stall and that would explain the seeming running of the unit without doing any cooling. Refrigeration

[Gene T]

Thanks to all for the good information. I was wanting to avoid becoming a refrigeration mechanic but that may be my destiny anyway. If/when it fails again I will have an idea what to check and whack.

Gene