Norcold N811 not cooling

[NSRV]

Hello everyone, I've a 2018 Jayco Redhawk 22J, equipped with a Norcold N811 (fanless model). Going to try to be as descriptive and informational as possible for you all here. I've searched and searched, tested and diagnosed, but before I start throwing parts, I need other RV tech opinions!

The fridge won't stay cold. It started losing temperature the other day in freezer and fridge, switched it from electric to LP gas, let it sit on for about 4 hours with thermometer inside the fridge, didn't seem to get cold. Outside ambient temperature has been from the low 60s (at night) to the uppers 80s during the day. Humidity is high, being West Virginia, no other issued with the fridge before this.

Verified RV is level (Re-leveled yesterday to be sure, 0.0 degrees front to rear, +0.3 degrees side to side, acceptable), fridge is confirmed level. Climbed up on the roof, pulled the vent bezel and inspected top side ventilation, no ventilation blockages found. Down below behind the access panel I did not find any yellow residue or ammonia smells to indicate a leak. The canister feels hot to the touch, and the electric heating element OHMs out good and gets hot. When on LP gas I can hear the igniter click and the LP burning, heater pipe gets really hot, which according to my research shows that is normal operation at that point.

I completely shut off the fridge and let it sit for about 4-5 hours until the canister on the back was no longer hot to the touch (to let it settle or burp, as I've read). I removed the circuit panel cover and performed the "board reset" that I found on google (grounding out 2nd pin on the right, top connector). Turned the fridge back on and let it sit over night. The next morning freezer was about 20F and lower fridge was about 38F. Worked great for most of the day but last night it started to get warm again.

Anything I can do to prolong the life of this fridge? It's not very old (Not sure if it has warranty still, or not, being a 2018 RV). I feel like maybe part of my issue is due to the fact that this model is not equipped with ventilation fans, and there is a fan kit available on Amazon. I don't appear to have a leak, perhaps cooling unit has a internal clog?

From the looks of it, based on my diagnostics and research, I may need a cooling unit. What are other people's thoughts on this? Also I've read that the pulling the fridge out and laying it on its side will unclog it, if it is clogged...

 

[donn]

Only used a fan one time. That was on a really old unit. Last refer a Dometic was in a slide out and worked perfectly for 12+ years until I sold the trailer. If you have the ability, and it sounds like you do. Turn off the refer, disconnect everything qnd take it out of the box. Turn it up side down for a day and reinstal. Try it and please report back. There have been several threads that indicate this trick has cured more than one.

 

[NSRV]

Only used a fan one time. That was on a really old unit. Last refer a Dometic was in a slide out and worked perfectly for 12+ years until I sold the trailer. If you have the ability, and it sounds like you do. Turn off the refer, disconnect everything qnd take it out of the box. Turn it up side down for a day and reinstal. Try it and please report back. There have been several threads that indicate this trick has cured more than one.

I will keep you posted, have been toying with this idea in my head. So upside down is the proper configuration to let it sit in then... I found many different options for the position in which to set it for this trick, but I'll do the upside down for a day and see where it goes. I'll work on getting it out this afternoon.

EDIT: Also, this RV does not have the kitchen slide-out, which I've read the kitchen slide-outs came equipped with fans. I wonder if it wouldn't hurt to put fan in while I'm at it...

 

[ChasA]

Your fridge might still be under warranty. You should check with Norcold before you pull the cooling unit.

 

[donn]

I will keep you posted, have been toying with this idea in my head. So upside down is the proper configuration to let it sit in then... I found many different options for the position in which to set it for this trick, but I'll do the upside down for a day and see where it goes. I'll work on getting it out this afternoon.

EDIT: Also, this RV does not have the kitchen slide-out, which I've read the kitchen slide-outs came equipped with fans. I wonder if it wouldn't hurt to put fan in while I'm at it...

Mine had no fans. Both the grils were on the side.
BTW, have you pulled the lower grill and looked around?

 

[Isaac-1]

I am not that familiar with Norcold units, but have you checked the thermostat / thermistor?

 

[NSRV]

Mine had no fans. Both the grils were on the side.
BTW, have you pulled the lower grill and looked around?

For mine, one on the roof and one down on the side of the RV at the bottom back of the fridge. As for fans, what I've read is that only the RVs that have kitchen slide outs had fridges equipped with fans, otherwise the draft created by the heat of the unit is "sufficient" enough to ventilate the system. I've accessed both areas and inspected for ventilation blockages and signs of leaking, but none found. I checked the circuit board that is behind the lower grille/access panel. Fuses were good on this panel and no burn marks or anything to make me consider its an issue, though keep reading, I think I found part of the issue.

Your fridge might still be under warranty. You should check with Norcold before you pull the cooling unit.

I will call them and find out, if it comes to that.

I am not that familiar with Norcold units, but have you checked the thermostat / thermistor?

This. I was getting ready to pull the fridge out to set it upside down over night, when it dawned on me I never OHM'd out the thermistor. I found a service manual for this Norcold model and had done the test of removing the thermistor from the fins and letting it dangle, and unplugging it as well. Didn't seem to make a difference, or maybe I was impatient.

What it boils down to is I pulled out the multimeter and tested the thermistor resistance (put it in a cup of ice water and checked resistance). Resistance readings on the thermistor are out of spec for the temperatures. At 32 degrees the multimeter reads 0L, which it should be 32 kOHM. At 80 degrees (or clenched in the palm of my hand) the multimeter reads 20 kOHM, according to the service manual chart this is way out of spec.

Also I unplugged the thermistor and turned the fridge back on, and look at that, there is frost in the freezer and the lower fridge is getting cool too, but after a few hours the temperature started to rise again, not sure if that's part of the fail-safe for having no thermistor or not. (Service manual says there is a fail-safe mode for when the thermistor signal is not detected.) Before I pull the fridge out or go any further I ordered a new thermistor off Amazon. For $18 what the heck, I'll try it.

 

[Gary RV_Wizard]

These days, turning the fridge upside down to burp it is mostly an old wive's tale. Has very little chance of success on a fridge built after about 1992. And even if it works, it is clearing a clog that will almost surely reform after a period of time. A clog is caused by sodium chromate in the coolant that has dropped out of solution, which only happens if the fridge cooling unit overheated badly at some time.

If the electric heater is on or the LP burner is burning, you know the thermister is doing its job. It's function in life is simply to tell the controller board to turn on the heat source. If that is happening, no need to investigate the thermister.

Your symptoms sound like the cooling unit has a pinhole leak somewhere and is slowly losing its coolant mixture. The first thing that escapes is hydrogen gas and that reduces cooling quite a bit, especially fridge area cooling. Then the ammonia starts to leak out and it gets worse. You don't always see any yellow residue. A leak isn't common at just 3 years, but it does happen.

A fan on the cooling unit can sometimes help, even if the unit is failing. Just take the lower access door off and temporarily place a small table fan at the opening, blowing inward to force more air thru. If that helps, you can buy & install a 12v fan kit.

 

[NSRV]

These days, turning the fridge upside down to burp it is mostly an old wive's tale. Has very little chance of success on a fridge built after about 1992. And even if it works, it is clearing a clog that will almost surely reform after a period of time. A clog is caused by sodium chromate in the coolant that has dropped out of solution, which only happens if the fridge cooling unit overheated badly at some time.

This is what I was thinking, I haven't pulled the fridge out yet... I'm going to call Norcold and see if it has warranty on it still.

If the electric heater is on or the LP burner is burning, you know the thermister is doing its job. It's function in life is simply to tell the controller board to turn on the heat source. If that is happening, no need to investigate the thermister.

I believe that the thermistor is out of spec. When I set the thermistor in a cup of ice with a thermometer and wait for the temperature to sink in, I get a reading of 0L (which typically means open circuit, no continuity), should be 0.30-0.32 kOHMs at 32 degrees. At room temperature (about 70ish degrees in here) I reads 53.1 kOHMs, should be 11.-12.0 kOHMs around 70 degrees. If I clench it in the palm of my hand I get 84.0 kOHMs, should be 8.1-9.0 kOHMs, according to the Norcold N811 service manual. I am still learning on RVs but my automotive and DC electrical experience scream at me that those readings are out of spec. Should I disregard these readings? I used two different multimeters on the 20k OHM setting (They both only have 20 OHM, 200 OHM, 20K OHM, 200K OHM and 200M OHM) and got the same readings on both multimeters.

Your symptoms sound like the cooling unit has a pinhole leak somewhere and is slowly losing its coolant mixture. The first thing that escapes is hydrogen gas and that reduces cooling quite a bit, especially fridge area cooling. Then the ammonia starts to leak out and it gets worse. You don't always see any yellow residue. A leak isn't common at just 3 years, but it does happen.

Is there anyway that I can indentify a pinhole leak on this style of system if there are no obvious signs? I've read its not good to use a soapy/foamy solution or leak detector solutions to locate the leak.

A fan on the cooling unit can sometimes help, even if the unit is failing. Just take the lower access door off and temporarily place a small table fan at the opening, blowing inward to force more air thru. If that helps, you can buy & install a 12v fan kit.

Thank you for that bit of information. A blow thru fan configuration would be better than a fan on the top of the vent pulling air through?

Thanks for the info Mr. Wizard

 

[Gary RV_Wizard]

I believe that the thermistor is out of spec.

You may be right, but that's not the immediate problem if the burner is burning (or electric heater heating) and the fridge still isn't getting colder. For now, just jumper 120v direct to the electric heat element so that you know its is running 24/7 and see what the cooling unit does. Once you verify it really does cool, you can go back and play with the thermister to see if it sends bad data to the controller. Note that if it reads too high, the only effect is to make the cooling unit run longer & get colder.

I've read its not good to use a soapy/foamy solution or leak detector solutions to locate the leak.

I've never heard that and don't believe it. However, it may not be practical on a super-hot boiler or the tube up to the condensor. And you would have to pull the fridge out to get at it.

A blow thru fan configuration would be better than a fan on the top of the vent pulling air through?

I'm only suggesting a temporary fan to see if it helps, e.g. prop up a small desk fan in the opening. It makes no difference whether you push or pull the air as long as it moves up the chimney and out the top. A puller fan up top is a good solution but hard to add without pulling the fridge. If adding a pusher near the bottom, just make sure it is sending the air upward and not back out the intake.

 

[NSRV]

You may be right, but that's not the immediate problem if the burner is burning (or electric heater heating) and the fridge still isn't getting colder. For now, just jumper 120v direct to the electric heat element so that you know its is running 24/7 and see what the cooling unit does. Once you verify it really does cool, you can go back and play with the thermister to see if it sends bad data to the controller. Note that if it reads too high, the only effect is to make the cooling unit run longer & get colder.

With me tinkering around with this fridge, I've found that it will get cold. If the unit has been shut off for a couple of hours, and I switch it on: After about 3 hours of being on, my freezer thermometer will read around 20F and the fridge thermometer will read around 38F, problem is, after reaching optimal temperature something causes the fridge to lose cooling, and the temperature rises up. It won't maintain the temperature. Temperature won't go back down unless I shut off the unit and leave it off for about an hour or so, then switch it back on. Upon switching it back on the unit cools down to the above mentioned temperatures, stays like that for a couple hours, then the temperature starts to rise again, which is why I'm leaning towards possibly a bad thermistor.

So, to better understand, would this also be the symptoms of a slow leak and/or clog in the system? I went ahead and ordered another thermistor if not I'll have a spare, I just want another thermistor that I can plug in and see if the issues clear up before I go any further with repair/replacement.

 

[NSRV]

Replaced thermistor and seems like the fridge is staying cold. Replaced it yesterday and let it run over night and stayed cool all night. 0F in the freezer, and fridge was 38F with the unit set to its coldest setting. Still staying cold currently. I'll keep you posted as we go.

 

[Kirk]

Any new reports? Is it still working?

 

[NSRV]

Any new reports? Is it still working?

Yes, the fridge and freezer are still cold It appears that the out of spec thermistor may have indeed been the issue. My trust has been shaken in this fridge though, none-the-less.... I'm keeping an eye on it for a while.

 

[Larry N.]

It appears that the out of spec thermistor may have indeed been the issue.

Sounds as if it changed values when heated (after using for a while).

 

[CharlesinGA]

I've had two Norcold N611 models and loved them, they work great. The N811 is just a taller model. I now have a Dometic and it works great also. A lot of problems can be traced to installation, proper baffling behind it to force the air moving upward to get into the fins near the top. It is not baffled properly it will not cool properly. Some RV companies don't care to do the right thing.

Glad to see you have resolved the issue.

Charles

 

[NSRV]

Sounds as if it changed values when heated (after using for a while).

Not sure, but I do know when I took the thermistor out and checked resistance via the table and procedure in the Norcold N811 service manual, all the resistance readings were out of spec. So far, still staying cold

I've had two Norcold N611 models and loved them, they work great. The N811 is just a taller model. I now have a Dometic and it works great also. A lot of problems can be traced to installation, proper baffling behind it to force the air moving upward to get into the fins near the top. It is not baffled properly it will not cool properly. Some RV companies don't care to do the right thing.

Glad to see you have resolved the issue.

Charles

This is the first thing I checked was ventilation and air flow. Didn't find any blockages below or up top when I removed the upper vent cover on the roof. So far, going over 48 hours of constant running, and its still cold.

Thanks all for the advice, any further issues I will keep you posted.