Norcold N611 Fridge... Gas Only Lights When Door Is OPEN

[LeafOnTheWind]

Hi, so this is a head-scratcher of a first post:

I just landed at my destination after five days of nonstop travel (as in, no time to even cook or clean, had to be here by a certain date - not my preferred way to travel, but duty calls). My fridge has been set to the middle setting this entire time, running on gas. I have warm tilapia, room-temperature eggs, and a tepid jar of pickles (among other things) stinking up my motorhome. To give you some context, this fridge has been a very low-key problem child since shortly after I acquired the RV last summer. The thermocouple probe in the fridge compartment went bad and it started freezing EVERYTHING/running constantly - so I just disconnected it, set the fridge temperature/cooling cycle frequency manually with the slider, and coped with the blinky light that means "aaaaahhhh, I can't find the signal from the thermocouple!" up until about... I think two weeks ago? Around that time I noticed that it had stopped blinking, but the fridge was still cooling to the correct temperature for the setting, same as ever. Apparently something  new happened during the last few days while I was wolfing down takeout on the road, and now it's just straight up broken.

Some preliminary testing reveals the following:

- If I set the fridge to 110v, I don't hear anything other than the "door is open" sensor click when I open/shut the door. This is, as far as I know, normal...? BUT I just connected to shore power, so I don't know if the fridge will cool down overnight if I leave it on electric.
- If I set the fridge to gas, keep the door closed, and put it on its coldest possible setting, I do not hear the gas burner light (it's got electric ignition and I know what that sounds like when it lights). At all. Even though it should be on since the fridge is warm.....

- But if I open the fridge door with it set to gas/coldest......... the gas burner lights right up and stays on UNTIL I SHUT THE DOOR. Then it poofs right out and I am left sad and thoroughly confused.

What on earth would cause this?!?!?! Is there some other "smart" sensor in there that's gone bad? Do I need to pull it and tip it upside down? Do I need to make some sort of blood sacrifice to get it to work again? Or just pony up the cash to replace a decade-old RV fridge?

Thank you for reading this wall of text, and if you have any idea as to what's going on or how to fix this, please comment and I'll try to follow along.

[Kirk W]

Welcome to the Escapee forums! While we are sorry that it took problems to bring you here, we are happy that you came and we will do our best to help.

The first thing which would help is to know a little bit of background information, like the make/model/ & age of the refrigerator you are dealing with. Do you have 12V power, as it is required for the refrigerator to operate in any mode? Most RV refrigerators go into a constant cool mode if the thermistor sensing temperature fails and disconnecting it should give that same result. Have you opened the outside access to the rear of the refrigerator to check there? If so, is there any odor of ammonia or any sign of a yellow gunk anywhere that you can see? What indicators light on the indicator panels and does the interior light come on when the door is open? 

[LeafOnTheWind]

It's a 2007 or 2008-era Norcold N611LT. I'm hooked up to shore power right now, and I've confirmed that it's doing the same thing (only activating the heating element/propane burner when the fridge door is open) on 12v/gas operation and 110v. The thermistor is what I disconnected almost a year ago (I don't need the interior light anyway - it was on the same circuit) when it got corroded and started making the fridge freeze EVERYTHING, and the thing was operating fine (as in, it cooled the interior more/less according to whatever temperature setting I slid the little switch to) until a few days ago. I popped the vent cover, and as far as I can tell everything inside looks just fine, no yellow guck or anything. The green top indicator light on the fridge panel (that's been flashing when the fridge is on since I disconnected the thermistor) is now staying on steadily unless I open the door, and then it goes back to blinking. The gas light comes on and stays on steady when I switch to gas-only mode or disconnect 110v. 

On both gas and 110v, I can hear the boiler heating element/propane flame ignite ONLY when the door of the fridge is open. If I close the door, the flame poofs out or the electric element clicks (very faintly) off. This feels like existential torture... after all, what good is a fridge that only operates when the door is open?

Need any more info?

[Darryl&Rita]

Check all the ground connections. It's possible the control board is grounding through the lamp circuit.

[LeafOnTheWind]

Wellllll.... I put my IT experience to work after tossing all the warm tilapia and pickle slices. I re-leveled, unplugged the RV from shore power, turned off the fridge, disconnected the battery switch, unplugged the fridge, checked all the connections (they seemed to all be tight and fine), and plugged it in/reconnected everything again. After that, it seems to be operating correctly on propane again, and I'm borrowing a thermometer to monitor it when I switch back to electric tomorrow, since that mode is darn near silent.

I hope someone in the future finds this post informative, and I hope it spares them the trouble of being sold a brand new fridge.

I'll report back if things change 🤞

[Kirk W]

Let me suggest that you visit the website of Bryant RV Service and download a copy of the service manual for the N61X series of Norcold refrigerators. Based on past experience, I'll be pleasantly surprised if your problem doesn't return. 

[Wrknrvr]

 I will say Darrly was highly probably correct with his statement.

 

 This type of problem can be very frustrating to figure out. As there was a way it would work but not the way it was supposed to work.

 

 Do not change anything and get settled in.    Now I would try to remember anything that seemed to be not plugged in correctly.

 

  But I would not touch it for few days unless it acts up again. Then I would have it on gas so you can tell when it comes on. Next would be the test every connection one at a time.

 

 Take a rest,.  Vern

[LeafOnTheWind]

Y'all were right... I'm having a different issue today after letting it run on the coldest setting all night and then opening it in the morning to get my pitcher of cold brew. 

After I closed it, I noticed that the propane hadn't cycled on in about half an hour, even though it's supposed to be on almost constantly when the fridge is set to its coldest setting... so I turned it off, cut the power sources, unplugged it and plugged it back in again, turned it back onto gas mode, coldest setting. Now it seems to be attempting to cool periodically, but I hear the gas flame light briefly, and then go out about a second later. Then it'll come on, and go out a few seconds later. Now it's on again, and holding steady.

I'm reading the technical manual, but I'm not very far in yet. 

[LeafOnTheWind]

"Backup Operating System (BOS) 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. N61X/N81X Backup Operation. When the N61X/N81X controls shift to BOS operation, the ON LED (green) flashes once every three seconds."

This is what I've had the fridge doing up until recent problems ^^^

It's started going back into this mode when I hold the door open again, and then not displaying an error code (but also not igniting the gas burner at all) when I close the door.

[LeafOnTheWind]

I am an idiot sandwich... Darryl&Rita were right, it was the disconnected wire for the thermistor/lamp assembly. The connector had gotten wet, and drying it off and plugging it into the light/unplugging it after a few hours has the fridge operating in backup mode again as far as I can tell. 

The moral of the story: change your thermistor when it goes bad, boys and girls.

[Kirk W]

On 11/14/2018 at 3:31 PM, LeafOnTheWind said:

This is what I've had the fridge doing up until recent problems

And that is the reason for the link that I posted to get a copy of the manual. Far less difficult to share the manual as compared to an amateur attempt to explain how it works.

On 11/14/2018 at 5:04 PM, LeafOnTheWind said:

The moral of the story: change your thermistor when it goes bad, boys and girls.

That would have been my advice, had it not been for the fact that you indicated it failed sometime before this all began. The constant cool when it detects a shorted thermistor is there because the designers believe that frozen vegetables are a better choice that thawed out tilapia. I didn't anticipate it being the cause for what you have now but would speculate that it was shorting out the control board.

[oldjohnt]

23 hours ago, LeafOnTheWind said:

Darryl&Rita were right, it was the disconnected wire for the thermistor/lamp assembly

CONGRATULATIONS to Daryl & Rita and you    !!!!!!!!!!!!!! Simple things such as Wiring/Connections are so often the problem !!!!!!!!!!!

Now you're a Happy Camper

John T  Live from SKP Headquarters in Livingston Texas

 

[Darryl&Rita]

In all honesty, that thermistor wasn't anywhere near what I was guessing at, but good catch. Thanks for coming back to let us know what the fix was. It helps tthe next guy to diagnose his rig.