Just replaced the cooling unit on my Norcold 1200 refig. Everything was cooling just fine so I brought it home to pack for the trip.
Went out and opened the door and no lights. Great I've blown another fuse.
Checked the voltage at the power board and I have 12VDc on the Brown power wire. 1 amp glass fuse and the 5 amp fuse are OK.
The graphic below is a simplified view of the necessary components of the DC (12 volt) system.
The DC system is pretty simple. DC (12 volt) comes into the Power Supply Board through terminals J3 and J4. When DC is called for, 12 volt is applied to the heat element through terminals J2 and J5. When DC is selected on Auto models, it overrides the other heat sources. Also, the 12 volt heat element is a smaller wattage heat element than its 120 volt counterpart and should not be used to draw down the temperature of the refrigerator from a warm start. The DC operation should only be used for a few hours while traveling and the RV battery is being charged. The lower wattage is to reduce the drain on the battery, but the drain is still heavy (19 amps on the larger models).
Troubleshooting. If you have a problem with DC operation, it's often a good idea to test the refrigerator on AC before going any farther. This lets you know that a few common components are working. After that, use a meter or 12 volt test light to insure that 12 volt is reaching the board through terminals J3 and J4. If anything works on the refrigerator, however, there is 12 volt at J3 and J4, because 12 volt is required for anything to work. Test terminals J2 and J5 for 12 volt output to the DC heat element. If voltage is going to the heat element and it is not getting hot (as verified by placing your hand lightly on the insulation pack above the gas burner), the heat element is bad. Allow 15 minutes for the heat element to warm up the boiler before verifying. Also, touch the insulation pack lightly at first, because a plugged cooling unit can cause the boiler to get very hot. If the heat element is getting hot, the DC operation is doing its job.
If you don't have 12 volt at terminals J3 and J4 (DC in), then there's no 12 volt to the refrigerator, which obviously is a situation that needs to be corrected. If you don't have 12 volt at terminals J2 and J5 (DC out), when the refrigerator should be operating on DC, the first place to look would be the 20 amp fuse on the Power Supply Board. You need to take the cover off the board to get to the fuse. If the fuse is good and there's still no power to the heat element, the most likely problem is the Power Supply Board. However, the eyebrow board (where appropriate) shouldn't be overlooked.
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