Norcold shutting off - Fixed!

[wnjj]

The Norcold N621L in our camper has worked relatively well since new for the past 12 years. After returning from a trip in July we left the fridge on while plugged in inside the shop. We left some condiments and drinks in there but nothing important. Things were fine until about a week ago when we wanted some ice cream that we had put in the freezer some time before. It was soft and melting and the fridge was warm. The LED indicated it was still on 'auto' but I noticed the interior light was not on and wouldn't come on after closing/opening door again.

So I powered it off and back on and the light started working and the fridge started back up. I tried LP mode and it lit up immediately and then I switched back to auto which chose AC. Using the diagnostic mode showed everything normal except it had saved something like 4-5 completely different error codes. I cleared those and left it running. Later that night it was cooling nicely and the next night I checked again and the Otter Pops were refrozen.

Skip forward about a week to today when I load the camper on the truck for this coming week's camping. It's totally warm again, shows an 'r' on the LED (center and lower left segments) which is not any legitimate code that I can tell. So I power cycled it again and read the diagnostic codes: "AC relay stuck closed" which is quite likely bogus as it would only cause 100% duty cycle cooling anyway. Now about 3 hours later the freezer is down to 5 degrees and all is well again. The 5-night camp trip is gonna take babysitting this thing plus coolers as a backup.

At this point I'm thinking loose connection, failing control board or maybe something else on 12V power making noise on the line. The camper's been plugged in as usual with a PD9245 onboard. It's tough to debug when it works fine after power cycling. Anyone else have this kind of random flakiness with their Norcold?

Update - Added a post where I replaced the relay and all seems well...for now at least. 🙂

[fourthclassC]

Wow , cool repair . Thanks for documenting it here. I have had a great deal of problems with my fridge but was resolved with a hard restart. Good to see the method to troubleshoot and replace this relay if needed.

[wnjj]

The controller board is under the cover with the white and yellow stickers.



Before starting I unplugged the AC power cord and opened the battery disconnect. I then unplugged the red/brown spark electrode wire and the two 12V DC pins. The 120V pins were on really tight so I used a screwdriver to gently pry them off after I dismounted the board.

The upper left and lower right screws hold the cover on and the other 2 attach the board in its plastic base plate to the wall.



Once the board is out on the table, I removed the plastic rear cover. The AC relay is the one here. It can be confirmed by looking at the back side of the board. One of its pins connects to one of the AC input pins and another goes to an AC_HT pin.



The replacement relay cost $2.05 but shipping added another $3.75. Here's the new relay next to the old. I got it here: http://www.digikey.com/product-detail/en/G5LE-1A-E-36%20DC5/Z5217-ND/1815659




Now installed on the board. It's a de-solder/solder job but only took 5 minutes.



I reinstalled and reconnected. The fridge ran perfectly on AC for 4 days so I'm declaring victory, for less than $6. If I just got lucky and it acts up again, a new control board is the next option.

[wnjj]

9 days and 1 camping trip later, it’s still humming along fine on LP. My replacement relay arrived in the mail. I’ll post pics when I repair the board.

[dougrainer]

wnjj wrote:

dougrainer wrote:
Do you understand what the "n" REALLY means? Doug

The service manual says exactly this: "No cooling detected by the controls". I abbreviated as "no cooling". My engineering guess is that code is set when nothing else is detected to be wrong but the thermistor is not ever dropping in temperature. It's what you'll get if the cooling unit itself has failed so no amount of flame or AC heater makes the fridge cold.

It's been fine all day so far on propane. At this point I'm going to say the relay has compromised contacts which sometimes work, sometimes stick on and sometimes are resistive enough to not cause an 'H' (open AC heater) but will not cool sufficiently.

Not Really. n or No/Co is a cooling fault. That means SOMETHING has caused the refer to NOT complete a normal cool DOWN cycle. Most common
causes of No/Co is lack of ventilation(or cooling fans inoperative) or running OFF level. But other things can cause it. This is a Cooling Unit protection fault, to prevent damage to the cooling unit. RV refers progressively cool down from the original interior temp---70 start and then 1 degree at a time until it reaches below 50 degrees and colder. IF you have an operational problem and the progression does not continue and stops, the controls sense this and stop the refer and throw the n(No/Co) code. You have ONE try to restart the refer, you turn it OFF and then back ON. DON'T find and fix the problem that caused the No/Co, it will throw a 2nd No/Co code and now your refer controls are locked out completely. You then have to do a HARD RESET. So, when you get the First No/Co code, check out the refer and determine what was happening that caused it to shut down. Doug

PS, after the first No/Co, if you restart and it does complete a correct cool down the FIRST code is erased.

[wnjj]

dougrainer wrote:
Do you understand what the "n" REALLY means? Doug

The service manual says exactly this: "No cooling detected by the controls". I abbreviated as "no cooling". My engineering guess is that code is set when nothing else is detected to be wrong but the thermistor is not ever dropping in temperature. It's what you'll get if the cooling unit itself has failed so no amount of flame or AC heater makes the fridge cold.

It's been fine all day so far on propane. At this point I'm going to say the relay has compromised contacts which sometimes work, sometimes stick on and sometimes are resistive enough to not cause an 'H' (open AC heater) but will not cool sufficiently.

[wa8yxm]

THe Fridge. believe it or not runs on HEAT. there are two heaters. Gas and Electric. if the Electric relay is stuck open as someone up-thread said. If A bug got onto the contacts and sacrificed himself to "Bug" you. (don't laugh folks the reason we call computer glitches is.. The first one was a real biological "Bug" (insect) on a circuit board. I've also cleaned several off power switches in my young life.. Not so many in my older life).

Other options include the famous Screw Loose that many folks seem to feel we .. Opps not that kind of screw. but a Genuine bad connection type screw.

And a bad heat element. (Where the screw is).

[dougrainer]

Do you understand what the "n" REALLY means? Doug

[wnjj]

So this morning when I checked it, it shows 'n' (no cooling). The only store code is the bottom segment on screen 5 which isn't defined in the 2004 manual I have so may be new to my model. I restarted it on gas this time since the problem seems to be getting worse. I ordered a relay already since it's only $6 and easy enough to try.

The missing 'r' mystery: My old hardcopy manual was 1998. Not real useful for a 2006 model.

[wnjj]

One other thing: If the relay sticks closed, doesn’t that mean it should stay cold? The wiring diagram shows the power cord, a fuse and that relay to the AC element. I can understand the board detecting AC when it’s not calling for it and faulting but if it can’t shut anything down, why is it warm? Maybe the controller faults and then the relay randomly opens some time later?

[wnjj]

While it’s still empty, I’ll let it run for 48-54 hours and then check on it again. If it is the AC relay, possibly aggravated by the defrost cycle, our 5 day trip should help prove that since we’ll be on propane the whole time. If the relay is the issue I’ll replace just it (I know it’s soldered), otherwise a Dinosaur board is likely on the list.

About the ‘r’ code. For some reason I didn’t see that in my service manual but when I looked online just now it says ‘r’ is indeed AC relay stuck closed which matches what the diag mode segment said. Looks like it is the relay not opening when either the set point is reached or defrost is called for and then the fridge shuts down.

Thanks a bunch for the comments and suggestions.

[Happytraveler]

I've had it with our 15 year old Norcold. One year ago it was playing games with us and had it fixed. Last week it was doing the same thing and we ended up loosing most of our food. Our motorhome is in the shop now and we opt not getting it repaired again, we are buying a new Fridge. Yikes, cost and labor for a small fridge $2400.00.

[dougrainer]

PaulJ2 wrote:
The way it's acting i would say the AC relay is stuck open. It does sound like a faulty relay. Maybe burned, dirty contacts.
That relay has to switch a 300 watt load on and off.

And if you have a relay fault code, even intermittent, you need to replace the rear Main control board. The relay's should NEVER malfunction. Doug

[dougrainer]

ScottG wrote:
Mine seemed to lose cooling for a short period last time we camped but I think maybe it was just going through a defrost cycle. Wonder how long a defrost cycle is?
Maybe that's what yours was doing?

The Defrost cycle happens every 48 to 54 hours when left ON constantly. It shuts the refer OFF for about 2 hours and then restarts. There is NO indication of this on the controls. Since it happens every 48 to 54 hours I do not know if the display goes dead or not. To STOP the defrost cycle is easy. Just turn the refer ON and OFF once a day and the timer restarts. Doug

[newman_fulltime]

Sounds like it cycles into defrost mode gets stuck and shuts down