Norcold Fridge not getting cold on electric (deeper dive)

[paparoscoe909]

Hi everyone,
Having trouble with a Norcold N7XF not working on electricity but it works like a champ on LP. The RV is a 2018 and recently new to me so I can't tell you what has been done to it in the past. The standard troubleshooting has identified no issues. Incoming power and all fuses are good. Heater has 47.5 Ohms and is receiving a 120v from the control board. Operator interface panel stays green like it should. Only thing is that it doesn't get cold. I have noticed there seems to be an embedded divider heater in the schematic that has me questioning the purpose of it and if it is possibly competing with the cooling heater. I do seem to get a burning electrical smell in the freezer more so than in the fridge but can't pinpoint the source or locate a hot spot. Any thoughts on what might be going on with this fridge or experiences with a similar problem would be appreciated. Would hate to be stuck on LP forever with this unit.

 

[dkoldman]

Have you or can you check the compressor?

 

[Morich]

No error codes showing?
I find the only way I can keep track of all the different versions of RV frig is to go for the troubleshooting manuals. This should be the correct one for that model but firs there are some basics to check.

https://myrvworks.com/wp-content/uploads/2020/12/Norcold-N7_N8-Series-Service-Manual.pdf

Down around page 16-17 there are some pre check type notes to follow to get the frig ready for operation or testing.
This is some basic to make sure it is connected, etc.

Obvious is the idea that it has to have 110AC connected!
But then it also has to have the temp set correctly:

These little mechanical brains can often be fussy and refuse to do what we want if we don't do what they say!
But if doing that and still not getting the correct green light on the front, I have to start down the list of indications that follow those first step instructions.
There are different ways to sort the problems on pages following but I note something on top right of page 20 whi9ch may sound correct for your problem. It mentions an AC lockout which might need to be reset??
Any chance the frig was tried to start when AC was not on hand like RV not plugged in yet?
Sounds like an easy thing to happen if we are not used to doing them in the right order!

Best of luck in the search. Do let us know what you might find as that is how we all get better!

 

[paparoscoe909]

Have you or can you check the compressor?

Hi dk.....this is an absorption type fridge....works great on LP....just not electric

 

[paparoscoe909]

No error codes showing?
I find the only way I can keep track of all the different versions of RV frig is to go for the troubleshooting manuals. This should be the correct one for that model but firs there are some basics to check.

https://myrvworks.com/wp-content/uploads/2020/12/Norcold-N7_N8-Series-Service-Manual.pdf

Down around page 16-17 there are some pre check type notes to follow to get the frig ready for operation or testing.
This is some basic to make sure it is connected, etc.
View attachment 1336478
Obvious is the idea that it has to have 110AC connected!
But then it also has to have the temp set correctly:
View attachment 1336479
These little mechanical brains can often be fussy and refuse to do what we want if we don't do what they say!
But if doing that and still not getting the correct green light on the front, I have to start down the list of indications that follow those first step instructions.
There are different ways to sort the problems on pages following but I note something on top right of page 20 whi9ch may sound correct for your problem. It mentions an AC lockout which might need to be reset??
Any chance the frig was tried to start when AC was not on hand like RV not plugged in yet?
Sounds like an easy thing to happen if we are not used to doing them in the right order!

Best of luck in the search. Do let us know what you might find as that is how we all get better!

Hi Morich....thanks for the input....Definitely a strange one....green status light is stable with no blinking....thing works like a champ in LP....was hoping to dig up a little better diagnostic information on the controller itself but striking out on the internet.....Definitely calling the AC heater to run and it's cold resistance is good.....I will keep digging into finding a fix

 

[dkoldman]

Hi dk.....this is an absorption type fridge....works great on LP....just not electric

Ah,,, I missed that. Sound like a control board then. If not, I got one more swing in my arsenal before I am out.

 

[Morich]

I've not looked at one of those boards in a while and it might be the wrong frig but I think there may be some fuses directly on the frig board at times. Maybe worth a check before going for new board?
Tracing the 110AC path through the board, you might find a burned spot but that is not an easy one to fix if the board is very complicated.

There is also a diagnostic mode for sorting trouble down about page 50. Not one I have used but seems to be a very complete setup to walk us through things that go beyond the lights on the frig.
When computer operations go off course it can often help to do some form of reset. Something like turning off the PC to let it's little brain cool!


EDIT?
PAGE 56 shows locations of three fuses on the board!

 

[Morich]

Looking closer, it appears that fuse F3 is directly in the 110AC line to the heater. That makes me think it possible to find most of the frig works but we get no heat from the AC heater if that F# is blown!

Possibly other power keeps the lights on! It would be logical to use the 12VDC input to power LED leaving the main use of the 110AC as heat..

 

[dkoldman]

Looking closer, it appears that fuse F3 is directly in the 110AC line to the heater. That makes me think it possible to find most of the frig works but we get no heat from the AC heater if that F# is blown!
View attachment 1336552

Possibly other power keeps the lights on! It would be logical to use the 12VDC input to power LED leaving the main use of the 110AC as heat..

 

[paparoscoe909]

Ah,,, I missed that. Sound like a control board then. If not, I got one more swing in my arsenal before I am out.

I am leaning that way too. Just didn't want to throw the dice. Maybe overthinking it. Definitely getting a peculiar smell in the freezer on electric that isn't there on LP

 

[paparoscoe909]

Looking closer, it appears that fuse F3 is directly in the 110AC line to the heater. That makes me think it possible to find most of the frig works but we get no heat from the AC heater if that F# is blown!
View attachment 1336552

Possibly other power keeps the lights on! It would be logical to use the 12VDC input to power LED leaving the main use of the 110AC as heat..

My schematic doesn't even offer the little bit of insight that your shows with regard to the controller operation. But item G in my schematic makes me wonder if that's what I am smelling when on electric. No smell on LP.

 

[Morich]

Yes, possible this may be what you smell. But that ay be kind of the start of a line of things that failed. maybe that item shorted out and made a hot spot to smell? And at the same time, it may have caused too much current to flow and that made the fuse blow?
Kind of going out on a limb without first checking?
So I would want to verify that the fuse is not blown and also that the 110 AC is actually reaching those two points listed as L1 and L2.
This drawing doesn't show clearly where and how the temperature is controlled by a thermostat and we know power doesn't just come in and through the heater full time as that would make it heat full time!
I would want to start with finding the connections are all as they should be, getting both 110AC and 12VDC at the points they enter the board.
There seems to be something really wrong if there are no error lights of any sort.
But there is an old idea. We may know what things do when they work right but if they work wrong, they can do pretty well anything they choose!
If you have the right inputs going in but the wrong things coming out, then it sounds like a bad board.
But first I check what goes in!

 

[WMGMAN]

From your first post is sounds like you have 120V at the heater terminals AND disconnecting the heater and measuring across the heater terminals gives you 47.5 ohms. Is the 120V measured with the heater connected (between AC_HT_LO and AC_HT_HI) or disconnected? If it is when connected, I would concentrate on a faulty heater that is going OPEN CIRCUIT when it starts to heat, but closed circuit (47.5 ohms) when it cools down. You could always put an ammeter inline with the heater to verify it is getting current (should be about 2.5 amps). If the 120V is when disconnected, try making the measurement while connected and see what you get. Most of the time heaters just burn out (open circuit or infinite ohms), but if a connection is failing it can be effected by the heat and act like a switch (off when hot, on when cold). On the other hand, if the voltage drops significantly when the heater is connected it means the current is being consumed by a high resistance inline in the unit and turned into heat (which could make your electrical smell).

All that to say, I would focus on the heating element first before replacing the controller.

 

[Bobn1957]

Hi everyone,
Having trouble with a Norcold N7XF not working on electricity but it works like a champ on LP. The RV is a 2018 and recently new to me so I can't tell you what has been done to it in the past. The standard troubleshooting has identified no issues. Incoming power and all fuses are good. Heater has 47.5 Ohms and is receiving a 120v from the control board. Operator interface panel stays green like it should. Only thing is that it doesn't get cold. I have noticed there seems to be an embedded divider heater in the schematic that has me questioning the purpose of it and if it is possibly competing with the cooling heater. I do seem to get a burning electrical smell in the freezer more so than in the fridge but can't pinpoint the source or locate a hot spot. Any thoughts on what might be going on with this fridge or experiences with a similar problem would be appreciated. Would hate to be stuck on LP forever with this unit.

Your ohm reading seems high to me, a resistive element starts out low and goes up as it heats! I suspect the element, you should be able to get a replacement!

 

[paparoscoe909]

Thanks for the input on this WMGMAN. All the measurements were taken cold and between the terminals with the heater disconnected. I am thinking along the same lines as you that the heating element may open circuit as it comes up to temperature. The motorhome is new to me and hard to work on in front of the house. I have a reservation at a campsite close to me in a couple of weeks to do some minor repairs and delve into the frdige situation a little more. None of the fuses were blown and it worked just fine on LP for the trial camping trip. It's definitely still a mystery but hope to have something figured out whether it's good, bad, or indifferent in a couple weeks. I will keep the group updated on the findings.

 

[paparoscoe909]

Your ohm reading seems high to me, a resistive element starts out low and goes up as it heats! I suspect the element, you should be able to get a replacement!

I was wondering about that also, Bobn1957. Was scavenging the internet for a spec on the heater and was only able to find something that suggested a range of like 35 to 50 ohms. That had me wondering if it was high for a cold value. Thanks for the input.

 

[kvmllr-WO]

Hi everyone,
Having trouble with a Norcold N7XF not working on electricity but it works like a champ on LP. The RV is a 2018 and recently new to me so I can't tell you what has been done to it in the past. The standard troubleshooting has identified no issues. Incoming power and all fuses are good. Heater has 47.5 Ohms and is receiving a 120v from the control board. Operator interface panel stays green like it should. Only thing is that it doesn't get cold. I have noticed there seems to be an embedded divider heater in the schematic that has me questioning the purpose of it and if it is possibly competing with the cooling heater. I do seem to get a burning electrical smell in the freezer more so than in the fridge but can't pinpoint the source or locate a hot spot. Any thoughts on what might be going on with this fridge or experiences with a similar problem would be appreciated. Would hate to be stuck on LP forever with this unit.

Our Norcold - in our 2022 Voyage - was cooling intermittently, regardless of propane or electric. Ultimately it required replacing the entire cooling unit. Thank goodness for the extended warranty that covered most of the nearly $3000 cost for those internal parts. Best wishes.

 

[Morich]

I like simple.
What if you ignore the specs if not finding definite answers and just go with seeing 110ac on the element and see if it gets hot AND stays hot?
OR? Let it do what you want and watch it get cold in the frig?

The problem with trying to outthink the machine is the number of tricks it may have. Things like the element may fail when they get warm but that can also be true of most any of the other parts.
Even as simple as one of those little snap on connectors may go open, so I like to stay simple and when/if it stops heating check to see where the circuit went open. It could be as simple as the thermostat shuts down way too soon.
If it stays working you are good but if it stops, I look for where the simple stops and chasing voltage is about as simple as it gets!

 

[paparoscoe909]

Our Norcold - in our 2022 Voyage - was cooling intermittently, regardless of propane or electric. Ultimately it required replacing the entire cooling unit. Thank goodness for the extended warranty that covered most of the nearly $3000 cost for those internal parts. Best wishes.

I hope it doesn't come to that. Don't have the luxury of an extended warranty plan.

 

[Morich]

I don't think you will be coming to total replacement as you have a different situation. With this type frig, heat is used to make the chemicals do the cooling!
If both electric and propane were a problem is then might be the chemicals.
But with the propane able to do the cooling, I have to assume the chemical parts are okay. No loss of them as when on propane!
If it works on propane and not on electrical heating, I lean toward it being a problem in the electrical, not the whole basic heat to cool parts! Most of the parts are the same, just what gives that heat and how it is controlled to work!