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weedrancher's avatar
weedrancher
Explorer
Nov 09, 2014

Norcold troubleshooting

I’m having problems with the refrigerator in my TC. The Norcold N510.3 refrigerator is 10 years old. It worked flawlessly until approx. 6 months ago. In AC mode the refrigerator/ freezer will cool down as normal and stay at approx. 35 degrees in the refer and 4 degrees in the freezer. After approx. 30 hrs, the refer warms up to 39 degrees and the freezer warms to 24 degrees. The temps will stay high for several hours then drop back down to the original temps.
The camper is level and parked in a large carport out of the sun. The outside temps are 41 at night and 75 during the day. There are no indications of a leak and everything appears to be in good shape. I checked the resistance in the heating element and it is 55.5 ohms. I also plugged the refrigerator into an extension cord. The refer temps stayed at 35 degrees and the freezer stayed at 17 degrees. The temps seem to stay consistent in LP mode.
The closest repair shop says they can’t recreate the problem and advised me that RV refrigerators only last ten years and was time to get a new refrigerator. I declared BS and I told them I’ll fix it myself. Anybody have any idea what the problem might be and what I should replace first?
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Nov 13, 2014
    Plugging the electric heat element directly into extension cord proved a few things:
    1) heater element works and properly cools fridge
    2) cooling unit works properly
    3) draft/air flow across cooling coils is not obstructed

    So temps fluctuating on BOTH electric and LP......
    Couple of things to check before replacing circuit board

    1) When the temps are not being maintained and increase check if fridge as gone into BOS (Backup Operating System----temp maintain by time cycle vs temp control
    To check.....press and hold TEMP setting button....temp setting will flash for 10seconds if in BOS

    That means..thermistor is problem

    2) Checking thermistor resistance
    Remove thermistor from fin (S/B on 5th fin from right)
    Place it in glass of ice/water with thermometer
    When temp drops check resistance at the 16 pin connector where thermistor wires are (pin 8 & pin 13) 8 is bottom left---13 is top row 4th from left
    AT 40*F........22.5K to 23.5K Ohms
    At 32*F........30K to 32K Ohms
  • weedrancher's avatar
    weedrancher
    Explorer
    Nov 13, 2014
    Old-Biscuit thanks for your suggestions. Other non–related projects has delayed me from responding. The LP mode stays consistent with AC mode. At setting # 5, the food section will cool down to 35* to 37* and 0* to 6* in the freezer. After several hours, the unit warms up (the last time it was 40* in the food section and 27* in the freezer) without any changes to the settings. I plugged the refer into an extension cord to verify that the problem was not the outlet. The same thing occurred. I unplugged the heating element and I plugged it into the extension cord and the unit cooled to 21* in the food section and -14 in the freezer. The amp draw was 2.02A at 117.5V AC. All connection have been checked. There are no obstructions to the vents. Where do I go now? I’m not opposed to replacing the circuit board if needed.
  • YC_1's avatar
    YC_1
    Nomad
    Nov 09, 2014
    Hello neighbor. We moved from YC to Florida a year ago.

    Video series

    Here is the start of several videos on troubleshooting. They are excellent.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Nov 09, 2014
    When you state " The temps seem to stay consistent in LP mode" does that mean that LP works correctly......food section 35*F & freezer 4*F (give or take)?

    When you plugged fridge into an extension cord....assume you mean plugged the fridge AC power cord into an extension vs the outlet in TC?

    You can run simple test....unplug AC heater element from control board and plug it directly into an extension cord then check temps next day. (bypasses control board---checks heater element capability and IF control board is issue).

    Also you can check AC heater element amp draw....should be 2.5A at 110V AC
    And the resistance should be 61.3 ohms at ambient temp (range of 58-64 ohms)

    Check AC heater element connections/terminals...loose, worn, corroded will affect how well they preform

    AND...check draft of outside compartment. Any obstruction....fallen down insulation etc. causing blockage will affect ability to cool as outside temps change

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