Norcold fridge backup operation

[Vacationer04]

How do I diagnose if my poorly cooling Notcold unit has went to backup operation? The Norcold manual mentions it but does not explain how to verify if that is what is occurring? The **** thing has been on for 4 days at high ambient temps of 80* day, and 70* night. It is a N8431M model which is equivalent to the now N841. I have tried the onboard diagnostics and nothing shows abnormal but it doesn't get cooler at any time in the freezer than 10* and fridge at 38*. I sure miss my 20 year old Dometic in my old coach than never seemed to struggle even in 90+* without any extra fans in the chimney/cooling unit area.

[Vacationer04]

I guess upon further review it is on "backup operating system". How do I reset it from that? I already know from calling the four local RV dealer service departments that getting in within 30 days isn't happening. The service manual doesn't say how to reset it, just see a technician. Surely there is a way for us do-it-yourselfers. Today at 86* ambient and not being opened for 2 days it was 13* freezer and 49* fridge on #9 setting.

[Vacationer04]

Thanks, Doug. I am prepared to do that as soon as I receive the fans. Either way I expected to pull the fridge. After 14 years I am sure it will lead me to poor insulation, too.
Can I use kraft or foil backed insulation to make it easier to attach to the refrigerator enclosure or must it be unlined?

[dougrainer]

The fans just remove the heat from the condenser. So, Installing the fans BELOW the condenser(about 4 or 5 inches) but above the lower tank and tubes is best. That means you have to pull the refer. Doug

[Vacationer04]

The fridge is not in a slide. It does not currently have a fan in the chimney area or if it does I am not able to see it or any wires that might connect to it. I am contemplating installing a pair of 120mm, 72cfm, 17dBa fans but I want to eliminate all other possibilities before that so I won't feel like I wasted money on them if it doesn't get better. I was advised to unplug the thermistor and that would put it in full on mode which is where it has been for several days. The temp readings I am getting are a result of that and are about 2* cooler than when it was connected, so I don't think that it is bad. If I follow the suggestion about the temp button it shows the normal procedure and shows #9 where I have it currently set.
When I get the fans I will remove the unit to install them and verify the condition of the insulation around it as it may be less than needed as we all know the factory doesn't overdo anything. This coach had the first 2 owners in Texas, verified through documents and service invoices that came with it, so I have to believe it must have worked better than it does now.
Is there a preferred way to install the fans? I have seen mounted on the cooling unit, mounted to the back of the fridge midway up and in the roof vent under the cover. Which way is the most efficient to get max cooling effect?

[Old-Biscuit]

IF the thermistor failed YOUR fridge would go into BOS
Per manual:

Thermistor Failure Fault –

The backup operating system (BOS) is an electronically controlled duty cycle that maintains the refrigerator in operation if the thermistor is disconnected or fails.
The BOS maintains cooling by timing the length of time the heat source is energized.
When the refrigerator is operating in BOS, the length of the cooling cycle has to be regulated manually using the TEMP switchbutton.
When a colder temperature is desired, changing the temperature setting to a higher number provides additional cooling by lengthening the cooling cycle.
For example, if the temperature setting is set to 5, raising the setting to 6 will lengthen the cooling cycle.
When a warmer temperature is desired, changing the temperature setting to a lower number shortens the cooling cycle.
For example, if the temperature setting is set to 6, lowering the setting to 5 will shorten the cooling cycle.

How to check if operating in BOS:
When the N62X/N82XN64X/N84X controls shift to BOS operation, the temperature setting flashes for ten seconds when the TEMP button is pressed.
After ten seconds, the selected operation mode indicator
displays.



"....doesn't get cooler at any time in the freezer than 10* and fridge at 38*."

Not best freezer temp BUT nothing to suggest cooling unit failure
Does it have a fan in outside compartment?????

[Joe417]

If the frig is in a slide out the fan may have failed. This will definitely limit cooling. With hotter ambient temps this can also cause it to not finish a cooling cycle which will set an alarm/error code and lock the electronics.

Check the fan.

[doxiemom11]

If it was in back up mode it would freeze everything in the refrigerator - at least that was our experience. Have you tried a reset? Unplug the 110, then unplug the DC plug ( our access is outside). Let it sit for a few minutes, then plug in the DC - then the AC (110) plugs. It may reset the circuit board for you for proper operation. Sound like your problem is it's too warm which could mean your thermistor is not working (like a thermostat). It's a cheap replacement and is inside plugged into the light with a wire running to the fins where it's clipped to the fins. Might try replacing that.