WITHOUT FRIDGE DEFEND YOU ARE NOT PROTECTED
Dometic & Norcold reliability and fire safety, can you live without it?
WITHOUT FRIDGE DEFEND YOU ARE NOT PROTECTED
Dometic & Norcold reliability and fire safety, can you live without it?
This page teaches how to test and fix Norcold RV fridge internal temperature sensor (thermistor) problems.
Instructions: Subjects are listed on left. Click the link to the right to go directly to the subject matter on this page.
The first and easiest thing to check is the location of the thermistor within the refrigerated cabinet. Use the photos below to find the location of the thermistor for your fridge model. Next we will discuss two simple ways to test the function of your refrigerator thermistor:
1) Use a thermometer in the fridge and compare the temperate to the temperature read out on the Norcold control panel while in the diagnostics mode. If the temperatures are similar, then the thermistor is working. Also, a remote fridge & freezer thermometer can be used like in the video above. Use the thermistor tables below to determine if the thermistor is working.
2) Use the chart below to get two resistors. One resistor will be the warm resistor (10k?) and one the cold resistor (30k?). Simply test to see if the fridge turns on and off with these two resistors. Use the warm resistor to run the fridge 100% of the time while measuring the cabinet temperature. This method should help narrow the problem down to being the thermistor or not. Also, when the thermistor is disconnected from the fridge controller, the fridge will run 100% of the time, as a result, if the food in your fridge is freezing the thermistor may need to be checked.
Next, if you think that the thermistor is failing, please note that there are two wires on the thermistor. On some refrigerators they go to a connector that also supplies power to the interior lamp for the fridge. Disconnect the connector and measure the resistance of the thermistor according to the table below. Please note that the table below is a copy of the Norcold 1200 repair manual. For your convenience see the table at the bottom of this page. You can pull the thermistor off and put it into your freezer, and then check it at the temperature in your RV. Please note, what you want to see is a change of resistance for the thermistor, not the exact reading in the table below.
3 Connector Troubleshooting) Please note in the 2nd image below, the thermistor has a connector (red arrow) within the fridge compartment. Look carefully at the thermistor terminal connections within this connector, often the connector thermals rust. This results in high resistance at the terminal; this can be the entire problem! We suggest cutting the wire off the connector and replacing the connector terminals with your own, then pack the terminals with silicon grease to prevent corrosion.
The photo to the left is a Norcold 1200 or 1210 Series thermistor attached in the proper position on the cooling fins. If the Norcold refrigerator thermistor is attached on the wrong cooling fin, the fridge will appear to not cool correctly. Please start by checking that your thermistor is located properly.
The next photo is a Norcold N7x & N8x thermistor in its proper location. Note that the thermistor is on the 10 cooling fin from the right of the fridge. Read the next section for testing.
The next photo is a Norcold N611/N641 thermistor in its proper location. Note that the thermistor is connected to a quick connector (red arrow). the yellow arrow points to the thermistor on the proper cooling fin. This connector can be seen in the following photo. The blue arrow points to wiring that we added so that we could test this thermistor with a data collection Fridge Defend control. Another method to repair the thermistor, just take it off the cooling fin and allow it to dangle in the fridge. This will keep the thermistor from cooling on the fin and could show a thermistor that the ohms at a given temperature shifted (drift) from its proper value, thus preventing the fridge from turning on.
The proper location for the thermistor for the N3104 and N3150 is on the 5th fin from the right on the cooling fins at the back of the refrigerated cabinet.
Proper location for the thermistor is on the 10th fin on the cooling fins at the back of the refrigerated cabinet.
Proper location for the thermistor is on the 5th fin on the cooling fins at the back of the refrigerated cabinet.
| Model | Error | Meaning |
|---|---|---|
| 2118 | Flash | When viewing cabinet temperature LED flash. |
| 2117 | C1 | Refrigerator thermistor out of range. |
| 2117 | C2 | Freezer thermistor out of range. |
| N3104 | 13.00 | Failed thermistor. |
| N3150 | 13.00 | Failed thermistor. |
| 1200 | Flash | When viewing cabinet temperature LED flash. |
| 1201 | Flash | When viewing cabinet temperature LED flash. |
| 1210 | Flash | When viewing cabinet temperature LED flash. |
| 1211 | Flash | When viewing cabinet temperature LED flash. |
| N1095 | Flash | When viewing cabinet temperature LED flash. |
| N510 | Flash | When viewing cabinet temperature LED flash. |
| N501.3 | Note 1 | |
| N501 | Note 1 | |
| N500 | Note 1 | |
| N401.3 | Note 1 | |
| N401 | Note 1 | |
| N400 | Note 1 | |
| N306 | Note 1 | |
| N305 | Note 1 |
NOTES
Note 1: Capillary Tube Type Sensor
The following tables are calculated values based on the information provided by Norcold. The values are presumed to be correct based on standard thermistor construction. At a given temperature the resistance is given if everything was perfect (Calculated ?). More importantly, the actual range of resistance should be between Range Low Ohm and Range High Ohm, but may still differ from these values somewhat because as thermistors age they drift. Norcold states that these values may be +/- 10% above and below the table values.
| Temperature (degF) | Temperature (degC) | Calculated (Ohm) | Range Low (Ohm) | Range High (Ohm) |
|---|---|---|---|---|
| -8 | -22.22 | 109675 | 102023 | 117328 |
| -7 | -21.67 | 106164 | 98786 | 113542 |
| -6 | -21.11 | 102777 | 95662 | 109892 |
| -5 | -20.56 | 99510 | 92649 | 106371 |
| -4 | -20.00 | 96358 | 89740 | 102976 |
| -3 | -19.44 | 93317 | 86933 | 99701 |
| -2 | -18.89 | 90382 | 84224 | 96541 |
| -1 | -18.33 | 87550 | 81608 | 93492 |
| 0 | -17.78 | 84817 | 79083 | 90550 |
| 1 | -17.22 | 82178 | 76644 | 87711 |
| 2 | -16.67 | 79630 | 74289 | 84971 |
| 3 | -16.11 | 77170 | 72015 | 82326 |
| 4 | -15.56 | 74795 | 69818 | 79772 |
| 5 | -15.00 | 72500 | 67695 | 77306 |
| 6 | -14.44 | 70284 | 65644 | 74925 |
| 7 | -13.89 | 68144 | 63662 | 72625 |
| 8 | -13.33 | 66075 | 61747 | 70404 |
| 9 | -12.78 | 64077 | 59896 | 68258 |
| 10 | -12.22 | 62146 | 58107 | 66185 |
| 11 | -11.67 | 60280 | 56377 | 64182 |
| 12 | -11.11 | 58476 | 54705 | 62246 |
| 13 | -10.56 | 56732 | 53088 | 60376 |
| 14 | -10.00 | 55046 | 51524 | 58568 |
| 15 | -9.44 | 53416 | 50012 | 56820 |
| 16 | -8.89 | 51839 | 48549 | 55130 |
| 17 | -8.33 | 50315 | 47134 | 53496 |
| 18 | -7.78 | 48840 | 45765 | 51916 |
| 19 | -7.22 | 47414 | 44440 | 50389 |
| 20 | -6.67 | 46034 | 43158 | 48911 |
| 21 | -6.11 | 44699 | 41917 | 47481 |
| 22 | -5.56 | 43407 | 40716 | 46098 |
| 23 | -5.00 | 42157 | 39554 | 44760 |
| 24 | -4.44 | 40947 | 38428 | 43466 |
| 25 | -3.89 | 39776 | 37338 | 42213 |
| 26 | -3.33 | 38642 | 36283 | 41000 |
| 27 | -2.78 | 37544 | 35262 | 39827 |
| 28 | -2.22 | 36481 | 34272 | 38690 |
| 29 | -1.67 | 35452 | 33313 | 37590 |
| 30 | -1.11 | 34455 | 32385 | 36525 |
| 31 | -0.56 | 33489 | 31485 | 35494 |
| 32 | 0.00 | 32554 | 30613 | 34495 |
| 33 | 0.56 | 31648 | 29769 | 33528 |
| 34 | 1.11 | 30770 | 28950 | 32590 |
| 35 | 1.67 | 29920 | 28157 | 31683 |
| 36 | 2.22 | 29095 | 27388 | 30803 |
| 37 | 2.78 | 28297 | 26642 | 29951 |
| 38 | 3.33 | 27522 | 25920 | 29125 |
| 39 | 3.89 | 26772 | 25219 | 28325 |
| 40 | 4.44 | 26044 | 24539 | 27549 |
| 41 | 5.00 | 25339 | 23880 | 26797 |
| 42 | 5.56 | 24654 | 23241 | 26068 |
| 43 | 6.11 | 23991 | 22621 | 25361 |
| 44 | 6.67 | 23348 | 22020 | 24676 |
| 45 | 7.22 | 22724 | 21436 | 24011 |
| 46 | 7.78 | 22118 | 20870 | 23367 |
| 47 | 8.33 | 21531 | 20321 | 22742 |
| Temperature (F) | Temperature (C) | Approximate Resistance (kOhms) |
|---|---|---|
| 32 | 0.0 | 30 - 32 |
| 33 | 0.6 | 28.5 - 29.5 |
| 35 | 1.7 | 24.5 - 25.5 |
| 40 | 4.4 | 22.5 - 23.5 |
| 50 | 10.0 | 15.5 - 16.5 |
| 60 | 15.6 | 12.1 - 13 |
| 75 | 23.9 | 10.1 - 11 |
| 80 | 26.7 | 9.1 - 10 |
| 85 | 29.4 | 8.1 - 9 |