Fridge About to Give Up The Ghost?

[Golden Echo]

Purchased our boat in 2008, came with a Norcold Fridge, just a cold box no freezer capability. The model is a "SCQT-6407.

The boat was custom made so the fridge was an add-on. Wiring is good, house bank is good (thank God) because the problem I'm having is when I am running on AC or DC current the fridge doesn't want to shut off or at least seems to run an awful lot. it seems to do better under AC power but not much. It does keep the food cold and when I touch the cold plate it is cold. The back part of the L is iced up a bit but I don't know if this could be effecting performance. Looking for advice/avenues explore.

Now before everybody starts bustin on Norcold (I've read the reviews), I can't complain about this one. The boat is an 87' and I think the fridge might have been purchased in 92' and has been working well to this point.

Waiting anxiously for any thoughts....

[Stu Jackson]

Thermostat?

When in doubt, ask

Technical Tips

[a64pilot]

Is it?
A. running all the time and getting too cold? That could be thermostat.
B. Or, I suspect running all the time and not cooling well, that is not the thermostat

Mine was an old as the devil Super Cold machine that wasn't cooling well. After some investigation I found that even though it was old as Methuselah, it was just simply undersized and I was faced with two options, reduce the size of the box, by insulated the fool out of it, or replacing it with something big enough to do the job.
I got with Rich Boren and he put me a dual cold plate system with a larger than normal compressor, it works, but it's obvious from the duty cycle I could do with better insulation.
How big is your box? How cold is the cold plate getting, it is freezing solid?

[Golden Echo]

Thermostat is a possibility. When it runs does not seem to be getting too cold. It will keep food and beverages cold and if I turn the thermostat down it will freeze water placed need the cold plate. So the thermostat could be the culprit or something called a Thermistor?

[Golden Echo]

Originally Posted by a64pilot

Is it?
A. running all the time and getting too cold? That could be thermostat.
B. Or, I suspect running all the time and not cooling well, that is not the thermostat

Mine was an old as the devil Super Cold machine that wasn't cooling well. After some investigation I found that even though it was old as Methuselah, it was just simply undersized and I was faced with two options, reduce the size of the box, by insulated the fool out of it, or replacing it with something big enough to do the job.
I got with Rich Boren and he put me a dual cold plate system with a larger than normal compressor, it works, but it's obvious from the duty cycle I could do with better insulation.
How big is your box? How cold is the cold plate getting, it is freezing solid?

Not sure how cold it gets. Lent my son my laser temp meter and haven't seen it since. Over this past summer my wife had to defrost it twice due to iceing it may need it again.

[paulajayne]

Originally Posted by Golden Echo

Not sure how cold it gets. Lent my son my laser temp meter and haven't seen it since. Over this past summer my wife had to defrost it twice due to iceing it may need it again.

Thermostat at fault - check that the sensing end is close to the evaporator.
Should be a small positioning clip.

[kas_1611]

I know this is going to sound really daft but what is the ambient temperature in the boat, and particularly where the unit is?

I had a similar problem with my unit this summer as the external ambient temperature was hitting 40ºC. With the sea temperature nudging 30ºC it was quite warm in the bilge and in the under space where the fridge sits. I contacted the manufacturers, who were fantastic, for advice and it basically boils down to the ambient being above the rated temperature for the unit.

Most, if not the vast majority, of cooler units are designed for temperatures around normal domestic averages and rarely exceeding 35ºC. If it is too warm then they continue to run. We also find the same problem if the ambient is close to the internal temperature of the fridge.

Frustratingly there isn't much you can do about the rating of the unit short of changing it. What I did do was add extra ventilation holes to increase the air flow through the compartment and added a small 2" dia computer fan to the system (0.24amp draw) to help suck the warmer air out and into the heads cupboard next door. This did help a little and along with some careful tinkering with the thermostat setting I was able to reduce the overrunning.

For completeness of information I have lined the interior of my fridge with 10mm of closed cell foam all around (15mm in paces) and sandwiched 20mm of catering foil covered foam and corrugated cardboard underneath to insulate the fridge. I also use an automotive interior/exterior thermometer to monitor the temperature and under normal usage the unit runs for 15-20mins every 120mins keeping between -2ºC and 8ºC in the lower half.

Hope that helps

Keiron

[captain mitch]

If the plate is makin ice then it is working.
Look at how much ice is building around the plate as that will reduce the efficiency of the box. You mention that it was an "added box" so you should also look at the clearance around the compressor and the external coils. You had a hot summer and if the air flow over the compressor and coils was limited, the compressor will run a long time. I recently added a pancake fan and a 100 deg thermal switch from Grainger to my fridge to circ. air over the compressor and ext. coil. It goes comes on automatic and greatly reduces run time.

[jamhass]

Assuming it is indeed a cold plate and not an evaporator, then check to see if the eutectic has leaked out. If so, refill it. Eutectics are generally a mixture of water and antifreeze. Don't have the specs handy, but you can google them.

[herbert.dietz]

In a old fridge you will loose the Gas (perhaps R137)by a small leak. you should refill it. if there is no valve to refill (valve like in a car tire) a Spezialist for cooling System can weld in one. cost me in caribean about 60,-.

[CapnBazza]

Had a similar problem, turned out the fins to cool the refrigerant had grown a firkin. About a half inch thick, no air got through or past it. Peeled it off, cleaned up the loose dirt and the fridge is as good as new. Good luck with yours.

[Hard Rock Candy]

What is a firkin? From your description it sounds like some kind of fungus. Sounds like something I do not wish to explore. Mac

[seasick]

http://www.thetford.com/wp-content/u...Parts-List.pdf

Scroll down to compressor runs continually.
Page 5

[paulajayne]

Originally Posted by Hard Rock Candy

What is a firkin? From your description it sounds like some kind of fungus. Sounds like something I do not wish to explore. Mac

It is like a merkin but bigger and fluffier.

[CapnBazza]

Thank you paulajayne, couldn't have explained it better. But it was autocorrect that substituted firkin for merkin, a firkin is a unit of measure, a merkin, well, google it. Fridges don't like either.