Fridge being picky about its power supply

[Martin S]

My fridge works fine on shore power or with the engine running. When running from the house bank (300 Ahr) which show to be fully charge, the fan runs fine and the compressor kicks in for just a few seconds ( and shows to be pulling approx 5 A) and so the frdge does not stay at temp.
I conclude that it is wired correctly but something is telling the compressor not to run. Puzzled. Can anyone enlighten me?

[Sailmonkey]

you've got a dirty or loose connection somewhere causing a voltage drop. When on shore or with the engine running the voltage is boosted up high enough to prevent the refrigerator control from shutting down for low voltage. Or maybe you have wires that are too small as well as a corroded contact.

either way, I suspect you're shutting down for low voltage.

[Bleemus]

Sailmonkey nailed it. You have a bad voltage drop somewhere.

[witzgall]

Yep, and if it a Santos compressor, you can change the voltage at which it cuts off, by putting a resistor between two for the electronic module pins. Check with your manufacturer for the details.

Chris

[witzgall]

That should have read Danfoss...

[Sea Life]

For my Dometic install, the manual gives wire sizes that are much much larger than normal given the small amp draw. These things are very sensitive to voltage. The manual goes as far as wanting it wired to batteries and not a distribution panel etc.

[Sea Q]

i'm assuming the unit is a 115 v ac
what type of sine have you got on your output from the inverter
I had a microwave and dishwasher act up without a true sign only to burn out their circuit boards after a while

[Privilege]

The same symptoms would show if your batteries were dead. The voltmeter shows them as being fully charged and when you are drawing low amps such as a fan or LED's, it's not a problem and you don't notice anything wrong. However, when you put a load on the batteries, such as a 5amp fridge, the batteries aren't up to the task. Look at your voltmeter when the batteries have been trying to run the fridge? If they are dropping fast, that is likely your problem. Alternatively, turn loads of stuff on so that you are drawing a lot of amps. Is your voltage dropping quickly...say less than 12v?

[TCL]

I don't want to hijack this thread, but I have a (perhaps) very similar problem that's cropped up in the past two days, and the folks who responded earlier may have some insight.

After replacing a burned out RIBU1C relay, my refrigerator was working fine, on shore power, although I thought it likely was not cooling to its full capacity. I took the boat off shore power for a few hours a couple of days ago and neglected to switch the inverter/charger to inverting mode, so the fridge stopped running. It did not start again, after re-connecting to shore power, until I flipped the breakers.

It then started running, and cycles like it always did, but it is *barely* cooling. It's been around 24 hours since it re-started and the temp has not gone below 52 degrees.

My plan today was to check the raw water strainer, pump, etc. -- inasmuch as it is running but not cooling. But reading the above, I'm wondering whether it is an electrical problem, like the voltage drop discussed above.

I'd appreciate any thoughts or suggestions for diagnosing. Thanks

*Edit: Compressor is a Copeland ARE27C3E-1AA-901

[bobnlesley]

Originally Posted by Sea Life

For my Dometic install, the manual gives wire sizes that are much much larger than normal given the small amp draw. These things are very sensitive to voltage. The manual goes as far as wanting it wired to batteries and not a distribution panel etc.

We found this when building/installing a boat fridge, I phoned the distributor and was advised to re-make the connections using BIG wires; I don't recall the gauges he quoted, but I do remember that they were qualified by their relationship to the length of the cable's run and that his over the phone suggestion was to: "find some wire that look twice as big as they ought to be and then buy the next size bigger."

[Martin S]

Thanks to all. The batteries are in good shape and no inverter is involved and the erratic behaviour points to poor connection or other voltage drop. That's where I'll start.

[Sailmonkey]

Originally Posted by TCL

I don't want to hijack this thread, but I have a (perhaps) very similar problem that's cropped up in the past two days, and the folks who responded earlier may have some insight.

After replacing a burned out RIBU1C relay, my refrigerator was working fine, on shore power, although I thought it likely was not cooling to its full capacity. I took the boat off shore power for a few hours a couple of days ago and neglected to switch the inverter/charger to inverting mode, so the fridge stopped running. It did not start again, after re-connecting to shore power, until I flipped the breakers.

It then started running, and cycles like it always did, but it is *barely* cooling. It's been around 24 hours since it re-started and the temp has not gone below 52 degrees.

My plan today was to check the raw water strainer, pump, etc. -- inasmuch as it is running but not cooling. But reading the above, I'm wondering whether it is an electrical problem, like the voltage drop discussed above.

I'd appreciate any thoughts or suggestions for diagnosing. Thanks

*Edit: Compressor is a Copeland ARE27C3E-1AA-901

If you're cycling, but not cooling, your thermostat sounds bad. If the compressor is running (so long as there is refrigerant in the system) your box is cooling. However if it's cycling, then the thermostat is telling it to stop cooling.

[Panacea2183]

Originally Posted by Martin S

My fridge works fine on shore power or with the engine running. When running from the house bank (300 Ahr) which show to be fully charge, the fan runs fine and the compressor kicks in for just a few seconds ( and shows to be pulling approx 5 A) and so the frdge does not stay at temp.
I conclude that it is wired correctly but something is telling the compressor not to run. Puzzled. Can anyone enlighten me?

What type of fridge?
Is it a Norcold?
May have simple fix for you

[Oceanride007]

Yes low voltage, always late at night when SOC of battery going down. Perhaps other things running contributing to voltage drop.
Solved the problem real easy, just connected the Neg returns together of the freezer and Refrig compressors. That way the voltage drop on the negative wire is reduced by a half, its enough. Good enough till I get around to rewiring.

[OzePete]

First check voltage at the 12VDC power in terminals on the Danfoss motor driver. (Large terminals) Check before compressor starts and again while it runs. If the voltage drops more than half a volt when running, or is less than 11.7 VDC then you have a 12VDC supply problem.
Next, disconnect fan and check to see if compressor stays running. If so replace fan.
Next, disconnect any other devices like chargers etc from your 12VDC supply and see if the compressor then runs.
If none of the above, then you may need a new Secop motor driver.
Cheers