Norcold 982 Issues

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Donebee

Member
Joined
May 27, 2019
Posts
21
I've been fighting this issue since last year with my Norcold 982IM fridge.

AC Heater failed on fridge last fall.

Replaced AC Heater last fall, but was still receiving C8 error, also replaced control board (Dinosaur Electronics) via warranty October 2019. Had purchased new board in April 2018.

Winter was approaching and couldn't continue diagnosing as I was storing coach for winter

Just got coach out for season, attempting to diagnose issue. AC Heater shows 45.6 ohms, technician at AC Heater vendor says it's control board.

Spoke with technician at control board vendor, he has me run a couple of tests, and then sends me yet another new control board.

Replaced control board, fridge runs fine on LP, but still shows C8 error and shuts off.

120V power at fridge outlet is good, 120V to board is good, 12V power to board is good.

AC Heater starts to heat up, but the fridge failed on AC within 90-120 seconds, showing the C8 error. (Per Norcold Service Manual - C8 = AC Heater Failed - Current out of Tolerance)

Any ideas?
 
The 900 series service manual says the heater ohms need to be between 38.3 and 42.3, so yours is out of spec at 45.6. Thus the C8 fault code is accurate.  At a guess, you have a high resistance short to ground, which is a fairly common failure mode in these heaters. If they don't just burn out, they leak a few milliamps of current to chassis ground, tripping GFCI (if applicable), triggering a fault, or maybe blowing the AC fuse on the circuit board.  It could be as simple as a single strand of wire touching the metal cartridge the heater sits in, or an internal crack in the heater rod allowing a tiny bit of current to escape.  And just to be complete, are you sure it is the correct wattage heater? 300W for this model, I think (see service manual).

http://bryantrv.com/docs2/docs/ncold900.pdf
 
Gary,

Thanks for the quick reply.

Yes, that's the first thing I checked this spring.

The AC Heater was replaced last fall, however I decided to double-check to ensure it was the correct part number, wattage etc.

The vendor for the part assures me that 45.6 ohms is perfectly fine, but this isn't my forte, hence the post. 
 
Do you measure any continuity from either of the heater leads to the boiler chassis?  If there's not infinite resistance from the heater to the chassis you have a heater to chassis short.
 
Gary,

The part is stamped with 120V, 300 watts, but who knows.

I did not measure resistance between the part and case, but I did check the part while it was still fairly hot and found 3-4 ohms between the plug ends and the shaft of the rod itself. The reading zeroed out once the part cooled.

I did order another part from a separate vendor, so I'm hopeful it is the heater. Perhaps I got a failed new part?
 
The vendor for the part assures me that 45.6 ohms is perfectly fine, but this isn't my forte, hence the post.
Click to expand...
Well, the Norcold 9xx service manual very definitively says it is NOT fine.  I don't have any more information than what is in the manual, but you can take your pick.
 
Gary,

Exactly what I thought, that's why I ordered a new AC Heater from another vendor.

Just wondering if there is something else I may be missing, as I stated, this isn't my strong suit.
 
Donebee said:
Gary,

The part is stamped with 120V, 300 watts, but who knows.

I did not measure resistance between the part and case, but I did check the part while it was still fairly hot and found 3-4 ohms between the plug ends and the shaft of the rod itself. The reading zeroed out once the part cooled.
Click to expand...

Since the shaft is connected to the refrigerator chassis when it's installed, that's a defective heating element with an intermittant heater to chassis short.  Most likely one of the heating wires expands enough when it's hot to touch the shaft and then retracts when it cools.  Good catch!
 
Lou Schneider said:
Since the shaft is connected to the refrigerator chassis when it's installed, that's a defective heating element with an intermittant heater to chassis short.  Most likely one of the heating wires expands enough when it's hot to touch the shaft and then retracts when it cools.  Good catch!
Click to expand...

I'm hopeful it's a good catch, new part should be here this week, keeping the old fingers crossed. Mama's on me to go camping! And you know what they say; happy wife....
 
OK gang, I received the new AC Heater and made the replacement.

Turned on fridge and bam, two minutes later the fridge again failed with the same C8 error.

So I?ve now replaced two AC Heaters and two control boards and still cannot determine what the problem could be.
 
I would begin to suspect the 110 volt supply to the power board. If the fridge is using a standard 110 volt electrical plug and receptacle, start by unplugging the fridge from the receptacle and plugging into a new cord from a different source. You could simply use an extension cord either directly from a plug in a power pedestal or from your home. If it is hard wired, disconnect the fridge at the junction point and run a new source to the fridge either from a power pedestal or from your home.  Test that. If you still get a C8 code, suspect any other cables or wiring that are exclusive to the 110 volt heating circuit that have been a constant with the board and element replacements. I would tend to think that you have proper control voltage (12 volts) since the fridge is working in the gas mode as it is all the same control circuit.

You may have metered good 110 volts but under load, it is possible that there may be a problem.
 
Already tried the extension cord, received the same results.

All 120V seems to check out.

 
See if you can use a different cord and plug on the fridge side. I am not sure how the plug is connected but it may plug into the power board or possibly use wire nuts but I would eliminate that next.
 
I have looked through this thread and do not see any details of the power source/sources being used to operate the fridge. Please post details of your 110 volt power options.

What have you been using and how did you bring in a different source of 110 volts with the extension cord?

Are you using a pedestal, campground, generator, home, Inverter, solar, adapters, power monitor, surge protector, etc?
 
I draw the power from an exterior power receptacle on my residence. I run an extension cord from there to the motor home. They both have been checked and are not the culprit. I also took a clock radio, removed the 9V backup battery, unplugged the fridge and plugged it into the circuit the RV fridge is plugged into; without any issues.
 
Henry J Fate said:
Do you have a generator? Have you tried to power the fridge from the generator?
Click to expand...
No, I?ve never tried that, but I just unhooked it from shore power, started the genny and ran the fridge, on AC power, without errors for ten minutes. It had been failing when hooked to shore power within 90-120 seconds.
 
I think we are reduced to clutching at straws here. What's different between genset and shore? Nothing in theory, but is this a motorhome with an auto transfer switch? That would mean a different relay path.  What voltage is your genset producing under load?  And I noticed you tested the fridge outlet with a tiny load, a clock radio, which is very low amp draw vs the 300W heater.  Nor do we know how sensitive that radio is to power wave form, voltage, etc. It's conceivable the clock radio works but a heavier load might not? 


You seem to have been quite thorough with your testing, but I'd go back to experimenting with the fridge plugged directly to another 120v power source, using another extension cord and a source outside the RV. Another outlet in the house than where the RV is plugged. Something is different about genset power (or it was one heck of a coincidence!). 

Last, what is the ohm reading for the latest heater? Curious to know if it is within the spec that Norcold manual says is required. Manuals have been wrong before, though.
 
Gary RV_Wizard said:
I think we are reduced to clutching at straws here. What's different between genset and shore? Nothing in theory, but is this a motorhome with an auto transfer switch? That would mean a different relay path.  What voltage is your genset producing under load?  And I noticed you tested the fridge outlet with a tiny load, a clock radio, which is very low amp draw vs the 300W heater.  Nor do we know how sensitive that radio is to power wave form, voltage, etc. It's conceivable the clock radio works but a heavier load might not? 


You seem to have been quite thorough with your testing, but I'd go back to experimenting with the fridge plugged directly to another 120v power source, using another extension cord and a source outside the RV. Another outlet in the house than where the RV is plugged. Something is different about genset power (or it was one heck of a coincidence!). 

Last, what is the ohm reading for the latest heater? Curious to know if it is within the spec that Norcold manual says is required. Manuals have been wrong before, though.
Click to expand...
Yeah, I?m getting frustrated that?s for sure.

Tested the fridge, unhooked from shore power with a separate outlet and cord and same error.

Yes, the motorhome has an auto transfer switch.

Tested the fridge on shore power, and the AC Heater shows a steady draw at 119.3 to 119.4V. Testing on the genny, with shore power disconnected shows a little higher, 120.4 to 121.4.

Ohm of the new AC Heater right out of the bag showed 45.8, higher than what the specs show.

When I used the clock radio I was simply testing the 120V outlet, to see if it was losing power as suggested elsewhere.
 
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