ISA Samoa Gelato Case with Eliwell ID974 - works great, then doesn't..

Hi. Nice forum.

I'm not a refrigeration tech.

The nearest qualified tech is some 500 miles away.
I am in eastern Oregon, USA.
I live and work 30 miles away from the gelato case I am inquiring about.

My friend has an ISA Samoa 6 gelato case. It is probably 20 yrs old, but really nice.
They bought it used 8 years ago. It gave them good service for 5 years, then sat in storage for 2 years, then was returned to service. When returned to service, it had a problem.

The problem - it works great for several days, then it goes to room temperature.

They endured 3 iterations of the following cycle: "remove melted product, clean case, call local service man, he plays with controller and cycles power and the case gets cold, pay service man, monitor cold temperature for 24 hours, put gelato in case, have 3 or 4 good days, then room temperature and loss of product."

The service man admitted that he did not understand the controller, and he stopped returning their calls.

That's where I entered the picture.

I visited my friend, removed service panels, inspected for obvious refrigerant leaks and loose or failed electrical connections. I cleaned underneath, blowing and brushing and vacuuming away dust. Nothing was very dirty. Not much dust anywhere. It was pretty clean. I powered the cooler up and watched it make compressor cycles and watched the immediate case temperature drop. Fans started and stopped. The case got cold.
I found a Samoa user manual and set the temperature range properly.
The case ran fine for 3 days, and then it returned to ambient.

So I did some more research.

I found a different forum where an Aussie recommended to replace the controller with a Dixell, but he did not specify a model number.

I found an ID974Plus service manual and learned that the ID974 comes in 240v and 12vdc.

This cooler runs on 120vac, so my assumption is that the ID974 board must surely be a 12vdc models, because other wise they would be transforming 120 to 240 to run the controller.
If the cooler was nearby, i would just go look for the transformer and confirm 12dc output to the controller terminals; but it's far away and i don't go that way very often.

So that's my first question: if an ISA Samoa with an ID974 is running on 120vac, the ID974 must be a 12vdc model, correct?

I read enough on this forum to learn that ID974's are common, and they have 40 programmable parameters, and Samoa coolers that melt product or get stuck in defrost are also fairly common.

My next questions are general:

If the case operates perfectly for 3 days and then quits, and that work-cycle can be repeated, I don't have a refrigerant leak, correct?

Are the older ID974's known to be failure prone, suggesting that the Aussie is correct and the controller should be replaced?

Does anyone here know which Dixell controller is the optimal replacement for an older Elliwell ID974 that runs a gelato case at -13°C? It would be good if the replacement dixell was the same dimensions as the eliwell.

Does anyone know of a U.S. distributor for new Elliwell ID974? I have looked, but apparently they all ship from Italy or other European countries.

Does anyone here think that the symptoms suggest that I should either attempt a thorough reprogramming session with the old ID974 to change fan cycles etc, or that I should just replace the controller?

Can anyone here recommend basic troubleshooting techniques?

I read enough to know that some good steps include:
1 - comparing fan cycles to compressor cycles,
2 - observing fan cycles related to defrost cycles,
3 - voltage or ohm checks of various components,
4 - temperature checks of various components (I have a simple IR checker good for up to 250°F),

I don't know what the exact steps are; open to tips or suggestions.

I have decent electronic and automotive skills.

When you see a 97 GM truck that becomes hard to start, you don't have to check ignition timing or plugs or injectors or intake because everyone knows it's the fuel pump, and that it will fail completely 4 days after the truck exhibits the 1st symptom.

If anyone here knows that I don't need to troubleshoot this cooler because it's definitely problem X, please say so.

Otherwise, I'm open to troubleshooting steps.

My only problem is that the cooler is far away, and i don't have large blocks of time I can spend with it. But I'm willing to try. :-)

Thanks!

hi I think that is a defrost problem

Simple question is when after three days the cooling stops, what is the system doing?

Is it all off and not trying to cool?
Is it still running the same as before but not producing any cooling effect?
Is the controller asking for cooling but the compressor etc not running?

Could be lots of things like controller software gone faulty so its not doing as it should. Relay could be bad so its on but not making contact. Defrost system could have a fault and taking three days to freeze up the cooling coil to the point air flow stops. You get the idea.

The questions to ask are what should the system be doing, and what is it actually doing?