DM2852 • DM2862 • DM2872 • RM2807 • RM2811 • RM2812 • RM2820 • RM2852 • RM2882 • DM3862 • RM3862 • RM3962 • RM3972 • RM4804 • RM4872 • RM4873

The Fridge Defend by ARP improves safety, efficiency, and reliability, can you live without it? This page show the install for the vast number of models Dometic makes for 8 & 9 cubic foot volume.


Table of Contents

Instructions: Subjects are listed on left. Click the link to the right to go directly to the subject matter on this page.

Dometic RM3862

Dometic 8 & 9 Cubic Foot Cooling Units

The Dometic 8 and 9 cubic foot fridges are found in both Class-A and Class-C motorhomes. In addition these excellent fridges are also found in many Fifth Wheel RVs.

The Dometic cooling unit design is very efficient when compared to other cooling units, but there is a trade-off for efficiency, these cooling unit are vulnerable to boiler overheating that can result in a damaged refrigerator, or even worse, a fire. Click here to see how the ARP helps prevent these problems.

This photo shows a typical Fridge Defend installation within the cooling unit compartment. The Fridge Defend is mounted directly to the Dometic control box. Please see below for wiring diagrams by refrigerator model.

Airstream RM2862

Airstream RM2862

This photo is a Dometic RM2862 with the Amish cooling unit installed in an a Airstream trailer. The owner of this fridge led Airstream caravans. This gentleman went through a number of refrigerators, both new and rebuilt. When he found out about the Fridge Defend by ARP he was intrigued to say the least.

One issue with the Airstream trailer is the distance the fridge is mounted from the vent. We highly recommend the Fridge Defend + Fan Control for this application.

Please click here for more information on the Fridge Defend + Fan Control.

RM3862 Amish Cooling Unit

Install Boiler Sensor

This photo is a Dometic RM3962 boiler, all of the 8 and 9 cubic foot fridges have similar boilers. The two green arrows show a crimp that is put into the boiler tube to hold the inner percolator tube in place. Do not place the tip of the ARP temperature sensor (blue arrow) so it straddles the gap resulting from these crimps.

Please be careful to position the ARP temperature probe away from the flue tube (red arrow). In addition, fill the area around the temperature sensor with insulation so that the area between the black arrow and the flue tube is packed. If there is a gap between the temperature sensor and the flue tube, the heat from the flue tube will give the temperature senor a false reading thereby preventing the control from functioning properly, thus fill all gaps with insulation.

Click here for temperature sensor install video.

Dometic RM3862 Cooling Unit

This photo is of a Dometic RM3663, it is similar to the above photo, but it shows more detail of the cooling unit compartment.

Please note the heavy power wires on the right side of this photo. Please be sure to always insulate these wiring harnesses that run through the cooling unit compartments. The heat from the cooling unit can melt the insulation on the wires, thereby causing an electrical fire. Yes, not all fires that originate in the cooling unit compartment are due to the boiler of your fridge overheating!

Wiring ARP Control on 8 and 9 Cubic Foot Dometic Fridge

RM2807; RM2811; RM2812; RM4804; RM4872 (Early 2-Way)

Please click here for the details of wiring the 2-way models without the boiler thermal switch recall.

RM2852; DM2852; RM2862; DM2862; RM3862; RM3962 (Late 2-Way with Recall)

Click here if your fridge has a boiler thermal switch that is wired in line with the power supply.

RM2807; RM2811; RM4804 (Early 3-Way Models)

For the early 3-way models where all of the current is routed through the power supply to the fridge control. The ARP can not power the 3-way heater and a relay is required.

ARP Fan Install

Please click here for the ARP blower fan and temperature sensor installation.

Please see the full ARP User Manual and Installation Guide for more information needed before using your ARPrv Control.

Dometic Service Manual Repair Specifications

Please note that all of the following specifications are believed to be accurate. If any errors are found, please bring them to our attention as soon as possible. For critical specification please contact Dometic as they make changes to their specifications without notice.

FRIDGE MODEL: RM2807; RM2811; RM2812; RM2852; DM2852; RM2862; DM2862; RM4804; RM4872; RM4873; RM3962

Parameter Value
Fridge Defend Boiler Temperature 185-195 degC
Fan Control Absorber Coil Temperature 120-135 degF
Off-Level Operating Limit Click Here
Minimum DC Power Supply 9.6 VDC
Maximum DC Power Supply 22 VDC
Maximum AC on 12VDC Supply Line 6 VAC
Board 12VDC Fuse 3 A
Board AC Fuse 5 A
VAC Operating Range 100-132 VAC
DC Heater Power Rating 215 W
DC Current 18 A
DC Heater Resistance per Heater (cold) 0.67 Ohm
DC Fuse 30 A
AC Heater Power Rating 325 W
Current 2.5 A
Heater Resistance per Heater (cold) 48Ohm
Gas Pressure 10.5-11.5 Inch-H2O
Gas Jet #53
Gas Thermocouple 25-35 mVDC
Electrode to Burner Gap 3/16 inch
Thermistor @ 33degF to 35degF 7k-10k Ohm
Please click here for more information on Dometic thermistor troubleshooting.

Dometic Service Manual Downloads

⇑ See above for troubleshooting info on this page ⇑

Service Manual Download: RM2852, DM2852, RM2862, DM2862

Service Manual Download: RM4804, RM4872, RM4873, RM2807, RM2811, RM2812, RM3807, RM3804, RM3862, RM3863.

Service Manual Download: RM2804 (manual control)

If you can not find what you need please use the Contact Us form on the top menu.