norcold 2 way fails when switching from AC to DC

Aubrey

I went through this last year when the trailer was new to us, There is a long post about it, and about the wiring diagram for the dc wires at the unit on the back of the fridge.
2018 T@B 400, no solar, 2 way fridge AC-DC...
Essentially I found that if I leave the battery switch in the cargo area ON, then plug into my shore power (with or without surge protector) the fridge stops cooling, fridge light still works.
After much effort to check what I could, I know that the DC power is good all the way through the fridge plug and to the unit on the fridge.    Mysteriously the fridge would start working again after sometime. 
This happened a couple more times until I realized the transition on or off of shore power was triggering it.
I started to always turn battery switch off when plugging or unplugging (probably a good idea anyway) and the fridge ran without trouble this way, until I forgot my method and plugged in this morning.
(I am in the midst of driveway testing my battery under dry camp conditions, another post I have going)
The fridge wont cool again even after pulling it out (pain) and test continuity and DCV.
I was thinking the control unit on the fridge has some built in surge protection of something, but it doesn't seem to be resetting this time.
I may be the only person this has happened to, but any Norcold 2-way experts out there?
Fuse good obviously
Puzzled and bummed in Ohio

Aubrey

UPDATE
After typing that post and about 15 min I checked again and it is cooling.
All I can figure is there is a surge even when unplugging shore power coming from the converter panel or as the fridge unit itself senses AC drop and switches to AC. Its 7 years old so I reckon I will just have to treat it like my 15 yr old rescue dog. Gently.
Still love to here from anyone who experienced this type of fridge issue or who understands that fridge control unit.

Denny16

One way to prevent surges in power, is to have a switch on the shore power outlet you are using, always turn off power to the shore power plug, before plugging in the TaB (or any trailer), get everything connected, then turn on the shore power outlet (plug you connected the trailer to).  

I installed a 30-amp disconnect switch on my RV shore power plug I have at home to do this.  At a campsite with hookups, you have the circuit breaker for the outlet being used in the pedestal, use this to turn off power to the outlet before connecting.  Do the reverse to disconnect.  Turn power users in the trailer off, Alde, CoolCat, etc., shunt off shore power outlet, and then disconnect.  This prevents blown fuses, resetting circuit breakers, etc.  

Not sure what is going on with your Norcold, we have the same fridge in our 2018 TaB400, never had this issue following the procedure I outlined above.  
Cheers

Aubrey

I imagine that is why your fridge doesnt have issues, you stick to the system.
It must temporarily protect itself electronically.
I have to remember this for the portable solar as well, they say hooking up the panels to control before hooking to the battery can cause damage.
I did accidentally unplug the battery first while repositioning the panels but i rushed over to fix it, seems ok...

Headed back over to my battery discussion this eve, its running the fan and fridge today without solar.
Learning a lot!

Denny16

My point @Aubrey, was you should try using this procedure to,se if it doesn’t solve some of your issues with the fridge.
Cheers

GigHarborTom

This is a big deal with almost all systems I have had resposiblity for... I learned the hard way, on backshifts in a 25 story building in Seattle 50 years ago, following major outage. We secured all big fans, electric boiler, circulation motors etc. I believe any system with numerous electrical components should be brought on line slowly one load at a time. While the utilities manager at a large navy base, I held classes for a lot of folks who were unaware why parts of systems would not recover by just resetting a major breaker. Sorry, just had to unload long ago experience.

Denny16

No worries Tom, this is just pain physics, you need to reduce the power load when being a system back on line to shore power.  Same goes for a ship, we shut down and restart power loads when shifting from ship power to shore power and the other way round.  I treat my trailer like a ship (or boat), and always start from cold iron and warm up systems one at a time when changing power sources.  I do the sam at home during a power loss, shut down the major power users at rye circuit breaker panel, start the Genny and then only startup the fridges one at a time, then the house lights.  Big users, like the 220-volt appliances (Oven) stay off until after power is restored. 

Cheers

Aubrey

I gotcha Denny16, and I agree. Looks like you have bben in a rig like mine for a lot longer. Thanks for the info!

Denny16

You are welcome Aubrey, we have had our TaB400 for about three years, and I previously lived in a 27-foot Kenskill trailer whilst in college years ago, and learned the hard way, what to do and not to do when moving this beast around.  I had to change trailer parks about three times, due to the older parks I was using (to keep cost down) being shut down.  We are all on a journey, learning as we go.  Happy camping and safe travels my friend.
Cheers

Aubrey

Im sure you will be hearing more from me on the forum. Great resource.

Aubrey

UPDATE
After a 3 day lakeside stay plugged in I brought the trailer home and left it on battery power in driveway. The fridge ran for another 36 hours that way.
Using the above method of turning off the battery cut-off switch,  turning off the breaker in garage then hooking up the power cords and surge protector then turned breaker back on AND...???
The fridge stopped cooling again. cranking up the setting knob wont get it to run. The blue light comes on after a delay when the door is opened, but no compressor activity. 

Aubrey

2 more weird clues, while the fridge was not cooling and the blue light was delayed upon opening the door, 
the propane detector was flashing its red light (next to the propane labeling)..
I spent a few hours messing with the satellite dish on our house (almost got it aligned, ha)
Went to check on the trailer and the fridge is running and the propane detector is back to green light status.
The fridge is set to coldest temp and clearly has started cooling only recently, and the blue light comes on instantly upon opening door.
There is an unusual set of symptoms to ponder on the forum.
Battery cut-off switch? AC/DC converter? 
Reckon I better check the wiring schematic, but the fridge has its own fuse for DC power, Maybe the propane detector trouble indicates a voltage issue.

Aubrey

Brand new renogy 200aH AGM battery, well above 50% at all times so far BTW

20amp circuit in garage pretty much dedicated to trailer

Denny16

Sounds like a loose wire connection in the fridge circuit some where.
 Cheers 

richardspahn

You'll love the Victron 3000 with the 2023 4 lithium batteries option. V3000 monitors all your circuits and manages the above problems and more.             As I've said before with V3000, don't front end it with a surge protector that shuts down with low voltage as V3000 supplements low voltage as necessary and shuts down if too low. Lastly, V3000 has "limited" high voltage shut down too but I will still use a surge dongle on park outlets as I never trust them when it comes to high voltage spikes. 

Sharon_is_SAM

@richardspahn - did you intend to post your message in another thread?  Aubrey has a new AGM battery.

Marceline

Aubrey said:

UPDATE
After a 3 day lakeside stay plugged in I brought the trailer home and left it on battery power in driveway. The fridge ran for another 36 hours that way.
Using the above method of turning off the battery cut-off switch,  turning off the breaker in garage then hooking up the power cords and surge protector then turned breaker back on AND...???
The fridge stopped cooling again. cranking up the setting knob wont get it to run. The blue light comes on after a delay when the door is opened, but no compressor activity. 

How low was your battery when you plugged it into power at home? The 2way fridge actually runs off 12v power even if you’re plugged into shore power. My theory is that if you run your battery down too far, the compressor won’t kick on until the converter has managed to restore the battery to some threshold (not sure exactly what that number is). 

Aubrey

It was not low on voltage, brand new renogy. After another day the norcold fridge is cool inside but I have been monitoring it and have yet to hear it running even with the temp control cranked up to 5. I was experimenting with the AC power and found that with all breakers off except the main one, there are TWO breakers that affect fridge.
The one labeled fridge does what you would expect, fridge powers on.
But the one labeled converter exterior kitchen also cause power to reach fridge.

It is all very puzzling, especially the delay in the blue light that comes and goes, and the cooling failure on AC and DC (though I understand even on shore power the fridge itself converts to DC).
Hate to replace it if it could be repaired. It gets cold enough to freeze a jug of tea when it does work.

Aubrey

Seems like some sort of low voltage cut-off malfunction, but when I verified voltage to the back of the fridge Im pretty sure it matched battery voltage at battery, and I have shore power plugged in again showing 13V battery and still no compressor activity.

MuttonChops

I have found this thread and @Aubrey original 'Fridge Wiring' thread very interesting to follow.  While a mere 320S owner with a 3-Way n180 Fridge cannot provide real-world specific knowledge for an '18 T@B 400;
I will provide some general side line observer comments

First.  The Model 400 has changed a lot since the initial 2018 release.  @Aubrey 2-way Fridge is not running only on 12VDC as the more recent build years.  Both his Control Model Wiring picture from last year and his recent comments on the effect of tripping WFCO Power Center AC Breakers supports this, his 400 has both 120VAC & 12VDC supplied to the Fridge.

attached PDF file has full diagram

Second. I fully agree with others that Turning Off All Trailer Appliances is the very Best Practice before switching from Battery Only to Shore Power. And at least switching the WFCO Main Breaker Off if an RV Park Pedestal breaker is not available should be included.
    However, having to disconnect the Battery is not standard.  If that is really the only way to avoid Fridge restart issues . . . it seems something else is wrong with the Fridge components.

Third.  Could all of @Aubrey issues be related to a poor production quality thermostat ?

Fourth. The nr740 does have thermal interlocks and while not normal, weird power surges due to not having everything off during Battery to Shore Power changes could be confusing it {most likely because that circuit is already weak}.
   The nr740 manual referenced by @Denny16 last year includes a simple LED Troubleshooting Lamp diagram (build instructions) and Thermal cutout is Error Light Flash Code 5 (see PDF).

Believe that's it for my observations.

Aubrey

Thanks Muttonchops for bringing that diagram out again. I was just talking to my wife wishing for service info to test the thermostat-thermistor, I would love to rule that out before moving on.
The wiring from the camper converter is a lot harder to access.
It can produce cold temps when it decides to turn the compressor on.
Norcold NR751BB

Aubrey

And since I have issues with AC and DC power it seems like a good next step

Denny16

I agree with Muttonchops, this is more likely an issue with the fridge unit, or the compressor is not coming on due to a low 12VDC voltage level, that is u dear the compressor’s minimum voltage requirement.  Our 2018 has the same fridge, and o have not had any issues switching between shore to battery power and back.  The fridge power source switches seamlessly.
 Cheers 

Marceline

Aubrey said:

It was not low on voltage, brand new renogy. After another day the norcold fridge is cool inside but I have been monitoring it and have yet to hear it running even with the temp control cranked up to 5. I was experimenting with the AC power and found that with all breakers off except the main one, there are TWO breakers that affect fridge.
The one labeled fridge does what you would expect, fridge powers on.
But the one labeled converter exterior kitchen also cause power to reach fridge.

It is all very puzzling, especially the delay in the blue light that comes and goes, and the cooling failure on AC and DC (though I understand even on shore power the fridge itself converts to DC).
Hate to replace it if it could be repaired. It gets cold enough to freeze a jug of tea when it does work.

I was speculating about the battery because in an earlier post you said that you ran the fridge on DC for 36hours before you plugged it back into power at your house. If you don't have solar, that would run down the battery by about 45-50aH maybe even more if the ambient temp in the trailer is very hot. Also, in another post you said: "2 more weird clues, while the fridge was not cooling and the blue light was delayed upon opening the door, the propane detector was flashing its red light (next to the propane labeling)." Both of those can be symptoms of a low battery. There can be enough power left in the battery for fridge and other lights to come on, but not enough for fridge compressor to come on. How are you measuring your battery state of charge?
Of course, all that is moot if you actually have the 110 line to the fridge and that line is working.

Aubrey

Finally got tired of trying to TRICK the fridge into working and after an extended period of not working on battery or shore again, I took the thermostat housing loose from inside fridge. I examined it for awhile, searched for replacement awhile, then went back and gave it a good tap with a screwdriver handle. Fridge started cooling within seconds. (on battery power)
I turned the converter breakers off, hooked up to shore, turned on garage power, knelt in front of the running fridge and flipped on the main breaker then the fridge breaker.
It switched to shore power seamlessly.
Ordered a thermostat from online seller (kind of hard to find?)
Part number 635832
Maybe I should have done this last year when the thing acted up?
HA!!! Lets hope they actually have one to ship. I will update between the 7th and 12th  

Aubrey

Denny16

Glad you got it sorted.
 Cheers