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Old 22-03-2021, 14:08   #1
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Troubleshooting Isotherm Refrigerator

I have an Isotherm CR130EL refrigerator.

Currently it is not cooling. The light inside is on so I am assuming that it is getting power.

I was having some trouble with my electrical and the batteries were low. Since this happened at the same time my hypothesis is that it shut off the condenser because the voltage was too low (from reading the user manual it seems it has this protection so it does not drain the batter), but then the compressor did not click back on.

I looked at the user manual and it talked about various lights to measure the status but I can't find where the lights are. I did not install it and I can't figure out how to get it out of the enclosure even to check the back.

Not even sure who to go to if I want to pay someone to repair it.

Any and all suggestions are welcome

Dan
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Old 22-03-2021, 15:03   #2
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Location: Ozefridge, Yarroweyah Australia
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Re: Troubleshooting Isotherm Refrigerator

Quote:
Originally Posted by djclancy999 View Post
I have an Isotherm CR130EL refrigerator.

Currently it is not cooling. The light inside is on so I am assuming that it is getting power.

I was having some trouble with my electrical and the batteries were low. Since this happened at the same time my hypothesis is that it shut off the condenser because the voltage was too low (from reading the user manual it seems it has this protection so it does not drain the batter), but then the compressor did not click back on.

I looked at the user manual and it talked about various lights to measure the status but I can't find where the lights are. I did not install it and I can't figure out how to get it out of the enclosure even to check the back.

Not even sure who to go to if I want to pay someone to repair it.

Any and all suggestions are welcome

Dan
Hi Dan, Most likely you do have a power supply problem. Once the Motor Driver Module (MDM) goes into 'off' mode due to low voltage, it has to see a voltage in the mid 12's to reboot into 'on' mode. So get your batteries charged up, then check the supply at the MDM terminals as described here:

Voltage drop test: (compressor tries fut fails to start or keep running)

Using a good multi-meter connected to the negative and positive terminals (- & +) on the MDM as shown below, read the voltage before and when the compressor starts or attempts to start.

The voltage reading with no load, before the compressor starts is meaningless but do note that no-load voltage.

Next, continue to monitor the voltage as the compressor starts or attempts to start. If this voltage drops away by say a volt or more or below 11 volts then that is confirmation that most likely the power supply / battery is the problem and that the compressor and MDM are not at fault.

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Old 22-03-2021, 15:18   #3
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Re: Troubleshooting Isotherm Refrigerator

Thanks for the reply.

So, since the problem I have had the power supply connected to shore power. So, I know that it has gotten above the 12v requirement (my power meter has it at 13.74).

However, my expectation is that it has not jump started it for some reason.

Any suggestion on the tricks to pull the frig out? Since I did not install it I am trying to figure out how to pull it out. Is there any way to screw it in or do I just need to figure a way to pull hard usually.

Thanks

Dan
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Old 22-03-2021, 15:52   #4
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Location: Ozefridge, Yarroweyah Australia
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Re: Troubleshooting Isotherm Refrigerator

Quote:
Originally Posted by djclancy999 View Post
Thanks for the reply.

So, since the problem I have had the power supply connected to shore power. So, I know that it has gotten above the 12v requirement (my power meter has it at 13.74).

However, my expectation is that it has not jump started it for some reason.

Any suggestion on the tricks to pull the frig out? Since I did not install it I am trying to figure out how to pull it out. Is there any way to screw it in or do I just need to figure a way to pull hard usually.

Thanks

Dan
Disconnect then reconnect DC power supply. Then suggest following the procedure I described above to see what voltage is actually at the MDM as it tries to start. I still think (hope!) you only have a supply / battery problem otherwise you may need to replace the MDM. (MDM only, the compressor itself is unlikely to be faulty)
Also bridge the terminals C & T with a jump wire to make sure its not a thermostat problem.
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Old 23-03-2021, 07:26   #5
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Re: Troubleshooting Isotherm Refrigerator

You can find voltage drop with a volt meter only if there is a long enough duration in low voltage drop. Unfortunately If this is a Danfoss BD compressor its low voltage safety circuit in electronic control module is more sensitive to short duration voltage spikes than any voltmeter. There are a number of items that cause these low voltage spikes old undersized refrigerator wiring, worn contacts in refrigerator switch or circuit breaker, a corroded wire terminal. Once you confirm there is more than 12.5 volts at module and compressor will not run there is one of seven reasons why voltage or amperage trouble. On Danfoss BD compressors made in the last 25 years there are previsions for a troubleshooting LED that when flashing will flash a code identifying which of the seven fault areas is causing failure of compressor to start up. In the absents of this LED the best way to isolate trouble is by bypassing all of boats wiring. By running jumper wires direct from a fully charged battery to the control modules plus and minus terminals of control module. Ninety percent of the time problem is a low voltage spike, if not fan is drawing too much amperage. To test fan as cause disconnect black fan wire from module terminal F. The rest of the troubleshooting will depend on system manufacturers design and model numbers.
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Old 15-10-2021, 05:52   #6
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Re: Troubleshooting Isotherm Refrigerator

Hi . This is not an on/off problem.. but another one. Hope someone can assist ??
We have two isotherm fridges in our lagoon 40 cat. Model CR 130 CT.
We have had problems with condensation and water build up in both if these units almost since new boat commissioning day, in France.
It occurs within 15 minutes of turning on.
Then within 3 - 4 hours post defrosting
the front of the freezer door and
The drip tray base are covered in water
Water drips into the food and gathers by the base of the door.
Food (covered) in the freezer becomes covered in fluffy ice as are the internal walls of the freezer cabinet. The slotted side panel bulges with excess ice and partially freezes items on the adjacent small shelf.
In less than a week the freezer door is jammed with ice and pressure must be used to open it.
The manufacturer's 3 to 4 mm of ice buildup occurs during this time.

Technicians have tested the seals, two new fridge doors have been fitted.
The fridges have large open spaces behind them..the techie says ventilation is fine.
We've taken fridge out if cabinetry to see if that helped. But problem remains exactly as when inbuilt.
We are in a temperate climate in the Canary Islands, the boat well ventilated, the humidity averages around 65 %.
The fridges are not running an unusual length of time and we are impressed with their "low" power consumption. We are only two persons, not a charter boat, doors opened infrequently, and with 30+ years of ocean sailing, familiar with boat systems..electrics etc.
Solar panels , solar water heating and good battery bank very adequately take care of our energy requirements. (Anyway these units have a low voltage cut off built in)

The manufacturers are going to replace one fridge under warranty to see if this solves problem. But they mention humidity might be a factor ,,???

Sorry about the lengthy epistle, but we are hoping someone out there might have a "clue"
Thanks
Pixie n Nigel
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Old 15-10-2021, 15:51   #7
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Re: Troubleshooting Isotherm Refrigerator

Your 4.5 cubic ft box when in use will have at least 3 cubic feet of air in it and each time compressor runs this air contracts. When compressor is off this air in box expands adding pressure to door seal. When air interiors box it contains moisture that collects on any thing cold allowing dryer air to exit through door seal while compressor is not running. Frost build up inside a refrigerated area is normal on cold evaporator plate but not normal in the area of door seal.

It sounds like door seal is not under enough pressure or the insulation inside door contains moisture. If Door insulation is the problem there will be condensation on outside lower front surface of door.

There is only one way to test the door compressed sealís tightness compression. Using a narrow cloth ribbon when closing door seal on it in many places around seal. With door closed on ribbon that place on seal should offer reasonable resistance when pulling ribbon out. Before magnetic sealing gaskets on refrigerator doors heavy over center latches were used to insure refrigerator door sealed tight. I am surprised your small fridge does not have a latch at both top and bottom, these RV type units do.
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Old 15-10-2021, 17:26   #8
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Re: Troubleshooting Isotherm Refrigerator

Hi Pixie n Nigel,
Firstly any fridge should be able to cope with 65+% humidity.
Most likely the cabinets are not sealed correctly or less likely the insulation is deficient.

The proper method of testing for cabinet / door seal leaks is to place a strong light inside the cabinet on a dark night and look for light escaping.. simple!

Once the light test identifies area(s) that are allowing air movement, you might like to try applying some pressure to the door to confirm/ repair the problem as follows..

Still using the light, place a strap around the fridge and door horizontally with a thick cushion between strap and door. Tighten strap to apply a pressure to the door and observe/ note the suspect areas that need attention/ packing.

If ever replacing door seals on small cabinets, consider using very soft closed cell sponge.

Cheers, Ozelouie
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Old 16-10-2021, 09:31   #9
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Re: Troubleshooting Isotherm Refrigerator

I searched your units solution of not compressing door seal enough, this is a common problem on these RV designed refrigerators. There are many door closer type latches even on Amazon for small boxes. Because more often than not these doors twist lightly maybe requiring two latches. The ribbon friction method is the only way to confirm low deferential air pressure can not pernitrate door seal.

Should the door seal test good with the ribbon test, all the way around seal, unit may need to be pulled out far enough to inspect holes through bulkhead around tubing for air leaks.
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Old 29-12-2022, 17:08   #10
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Re: Troubleshooting Isotherm Refrigerator

We have had our isotherm fridge for less than a year and it freezes almost all the food. Bottom compartment completely frozen, top shelf is the only one that does not freeze
. What is the problem?! At wits end trying different things.
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Old 09-06-2024, 08:47   #11
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Re: Troubleshooting Isotherm Refrigerator

There is a series of you tubes on danfoss powered fridges
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Old 24-06-2024, 16:54   #12
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Re: Troubleshooting Isotherm Refrigerator

My isotherm drawer fridge has been intermittent lately. Compressor doesn't want to start. Here's what I've done

Voltage with nothing running input into mdm power supply board on back of fridge 12.4v

When compressor kicks on drops to 10.2 then shuts off.

If I bypass the fan that helps a little 12.3 but still does below threshold.

If I short terminals c and t to bypass thermostat, compressor stays running at 11.3v

So I thought it was the thermostat but if I short the actual wires at the thermostat it still drops to 10.2 and cuts out. So maybe the little circuit board that plugs into the mdm coming from the thermostat?

If I run the generator and battery charger, it stays around 11.5 and stays on.

I know some may say batteries but like I said these are new and charged, never had an issue with these. My previous boat had weak batteries and never had an issue with fridge.

Ordered a new mdm board, I'll test tomorrow.
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