Norcold N611 sudden AC issue

[elraie]

I have always been running my 2007 N611 on AC shoreline (permanently parked RV).

A few weeks ago, AC suddenly stopped working on the fridge, and it went over (auto) to LP without issue. I have tried power cycling and removing AC power several times, but it still constantly defaults to LP. No error codes LED flashing.

Went through the service manual checklist. I am getting good AC (118v) at the control board, and the heater element terminals, and good 12vdc to the board. Fuses on the board are good. Main panel fuses good. Heater element resistance is 47 ohm, which seems within spec. Trailer is level.

Tried plugging in a new heater element, no change, still defaulting to LP. Purchased a new control board, installed it and exact same issue, defaulting to LP.

Am I missing something? Are there any other suggestions, as I've pretty much covered everything I could think of.

[elraie]

enblethen wrote:
What method are you checking 120 volt power to refer?
Use a known good item such as a drill to test receptacle.
A volt meter in some cases will read induced voltage.
Verify connections in 120-volt distribution panel.
Remove receptacle from refer access. Some of the rigs use stab type receptacles that don't always make good contact.

Was using a dmm to check for 120v at the fridge supply cable,and across fuse terminals on control board. Panel was fine, nice and tight on buses. As stated earlier, can't access receptacle as it was installed very high up, cooling unit in the way. But I just tried with the 2nd outlet on refer recept, and that one is working. No signs of arcing or oxidation on refer plug, so hard to tell what happened. Still think I'll disconnect that outlet, and rewire something more accessible. Thanks for the info.

[Mmaxed]

elraie wrote:
@Doug: so no luck with the 12v direct to car battery method. Checked optical board, reseated wires going into the jumper, no luck.

But then I decided to pull the AC cable and try it on an extension cord, and it immediately switched over to AC.

Since the extension is plugged to the RV (fed from main panel), I'll assume this is a fridge outlet issue, and not AC ripple? But I was measuring good AC voltage going to the control board when it was plugged into the fridge outlet, so I'm a bit stumped.
Trouble now is that they buried the fridge outlet box so high up, it's not accessible without removing the cooling unit. Seems easier to trace this fridge supply wire back to the panel, and just install some new romex and outlet box.

Maybe check the breaker. Could be it's not letting enough amperage through.

Thanks again for your help!

[enblethen]

What method are you checking 120 volt power to refer?
Use a known good item such as a drill to test receptacle.
A volt meter in some cases will read induced voltage.
Verify connections in 120-volt distribution panel.
Remove receptacle from refer access. Some of the rigs use stab type receptacles that don't always make good contact.

[elraie]

@Doug: so no luck with the 12v direct to car battery method. Checked optical board, reseated wires going into the jumper, no luck.

But then I decided to pull the AC cable and try it on an extension cord, and it immediately switched over to AC.

Since the extension is plugged to the RV (fed from main panel), I'll assume this is a fridge outlet issue, and not AC ripple? But I was measuring good AC voltage going to the control board when it was plugged into the fridge outlet, so I'm a bit stumped.
Trouble now is that they buried the fridge outlet box so high up, it's not accessible without removing the cooling unit. Seems easier to trace this fridge supply wire back to the panel, and just install some new romex and outlet box.

Thanks again for your help!

[elraie]

dougrainer wrote:

elraie wrote:

dougrainer wrote:
Disconnect the 12 volt supply to the refer. Use a SEPARATE 12 volt supply. Either a regular car battery or a 12 volt battery from a electric power tool. Then see if the problem goes away. If so, report back. Doug

Thanks Doug. Will try when I get back to camp next weekend. What's the reasoning behind separate 12v - in case something wonky with the 12v coming off the converter? I had good voltage at the board, but I didn't check amperage.

AS Converters and Inverter/Chargers age, they sometimes send off RF to the 12 volt system causing electronics to malfunction. Refer and AC control boards are susceptible to this. You have replaced all parts except the optical board. BUT, the Main control is what controls 120/LP. Doug

Gotcha! And to be honest, my old WFCO I/C had a few odd glitches last season under load (unrelated to this fridge issue). Hopefully you're on to something here. Will post my results, thanks for your suggestion!

[dougrainer]

elraie wrote:

dougrainer wrote:
Disconnect the 12 volt supply to the refer. Use a SEPARATE 12 volt supply. Either a regular car battery or a 12 volt battery from a electric power tool. Then see if the problem goes away. If so, report back. Doug

Thanks Doug. Will try when I get back to camp next weekend. What's the reasoning behind separate 12v - in case something wonky with the 12v coming off the converter? I had good voltage at the board, but I didn't check amperage.

AS Converters and Inverter/Chargers age, they sometimes send off RF to the 12 volt system causing electronics to malfunction. Refer and AC control boards are susceptible to this. You have replaced all parts except the optical board. BUT, the Main control is what controls 120/LP. Doug

[elraie]

dougrainer wrote:
Disconnect the 12 volt supply to the refer. Use a SEPARATE 12 volt supply. Either a regular car battery or a 12 volt battery from a electric power tool. Then see if the problem goes away. If so, report back. Doug

Thanks Doug. Will try when I get back to camp next weekend. What's the reasoning behind separate 12v - in case something wonky with the 12v coming off the converter? I had good voltage at the board, but I didn't check amperage.

[dougrainer]

Disconnect the 12 volt supply to the refer. Use a SEPARATE 12 volt supply. Either a regular car battery or a 12 volt battery from a electric power tool. Then see if the problem goes away. If so, report back. Doug

[elraie]

enblethen wrote:
First item that fails in many AC functions in the refer is the 120-volt element relay.
New circuit board time!

Thanks, but as I mentioned, I did replace the board, and still having the same problem. Only thing I did not test was the control panel. The selector switches are working fine, but maybe the processor is not triggering the main board to switch to AC. Really stumped with this.

[enblethen]

First item that fails in many AC functions in the refer is the 120-volt element relay.
New circuit board time!