N811 • N820 • N821 • N823 • N841 • N842 • N843 • NX811 • NX841 • NXA811 • NXA841

Fridge Defend Location

The photo to the right is a Norcold 811 cooling unit with the Fridge Defend mounted on the factory refrigeration controller cover. The Norcold, N8xx & NXA8xx all have slightly different controllers, but the principles behind the operation and control of the different models is all similar. The fridge in this photo is a Norcold N841.3, where the ‘.3’ indicates that this is a 3-way fridge. Please note that there is a black and yellow pair of wires going to the electric heating elements. One wire pair is for 12VDC heat source and the other is for 120VAC heat source to drive the refrigeration process. Due to the high amperage draw for the 12VDC, most users only run the 12VDC when they are driving, we do not recommend using the 12VDC heaters as they can damage the fridge if your fridge is not protected by the Fridge Defend.

Wiring Fridge Defend by ARP with Boiler Housing Thermal Switch

The following two drawings show the typical methods of wiring the ARP with the Norcold N8xx series.

The first figure shows the older style wiring scheme. On these refrigerators the power is routed into the boiler housing thermal switch and then to the Norcold control. The Fridge Defend is just wired inline with the power wire to the thermal switch. Power coming from the RV is connected to the ARP red wire, the ARP yellow wire is connected so it sends the power to the Norcold control.

Wiring Fridge Defend with Boiler Housing New Style Thermal Switch

This next drawing shows the newer style wiring. The boiler thermal switch is wired directly to the Norcold fridge control circuit board. In this case, just remove the 12 Volt power wire from the Norcold control and connect it to the red ARP Control wire. Next, connect the ARP yellow wire to the location on the Norcold control where you removed the power in the earlier step, this will complete the power circuit.

Late Model N8xx.3 & NXA8xx.3 3-Way Fridge

This drawing shows how the original wiring is on the Norcold controller (2). Please note the purple wire (the color of your wiring may differ) with the brown arrow. This wire will be removed in the next step.

Remove the jumper between terminal 2 and 6 and connect the ARP red wire to terminal-6 and the ARP yellow wire to terminal-2.

ARP Temperature Sensor

The final photo shows the boiler housing door open, and the boiler sensor of Fridge Defend Control is clipped onto the boiler tube. All versions of the Fridge Defend use the same sensor installation. Please note that insulation is placed between the temperature sensor wires and the boiler tube. This installation is helpful because the temperature sensor cable is isolated from the boiler tube. Do your best to insulate the boiler housing so that heat loss does not affect the cooling efficiency of your fridge. Also, insulate the sensor wire where it passes through the sheet metal boiler housing, the sheet metal will cut the sensor wire and cause the Fridge Defend to display short (SHt) if the wire is not wrapped with some kind of protection.