Mod: 3-way to 12v DC Compressor Refrigerator Upgrade
DETAILS: 3-way to 12v DC Compressor Refrigerator Upgrade
I’ve had two 3-way refrigerators (my original N3150 and an updated N4150 that replaced it) and the cooling units on both ultimately failed. I decided to finally switch to a 12v DC compressor refrigerator, and I couldn’t be happier that I did! I purchased the Norcold N2175 which is a direct size replacement for the N3150 — it fits in the same “hole” without modifications to the height/width and no need to rework the wood trim. However, there are some modifications required to the inside cabinet depth and the sealing of the outside vents (details below). It’s a relatively straight-forward DIY install and the benefits of this model are many. I’ve had it running 24/7 for two months and it’s been flawless.
Benefits of a Compressor Model:
Gone are the days that you must have the RV level — a compressor refrigerator runs on any slope. Whether you’re driving, parked, boondocking or have 120v hookups, it always runs on the 12v power of your house batteries. These type of refrigerators became standard on View/Navions halfway through the 2018 model year. The fridge/freezer temperatures are predictable and they recover quickly from opening the door and/or introducing new food. Compressor refrigerators don’t have the evaporative cooling unit on the back, so the depth of the interior space is considerably larger despite similar exterior dimensions.
Benefits of this Model:
This model has separate temperature controls for the refrigerator and the freezer, so they can be set to different settings independently. In fact, you can turn off the freezer (or defrost it) without affecting the refrigerator. It’s pretty neat! If you’ve ever had to compromise between frozen ice cream and frozen produce, now you can have the correct temperatures in both compartments.
Unlike many compressor models I’ve seen/heard, this one is actually quiet! I like things quiet and dark when I’m sleeping, and the sound it makes blended in after the first day. I was really concerned about the noise of a compressor (compared to my silent 3-way), but it’s turned out to be a non-issue with this model. No loud clicks of relays and it emits just a low frequency hum when it’s running. The compressor, fan and all electronics are at the bottom of the unit, below the freezer. So from bed, any sounds are close to the floor and are barely detected.
The N2175 has a pull-out freezer drawer which has two benefits. First, it’s easier to organize and retrieve items from the freezer because you’re looking down into it vs. stacking layers horizontally. Second, due to the freezer on the bottom, the refrigerator door is higher up and items are at eye level which makes for a pleasant day-to-day experience.
The freezer is about the same volume, but it seems like you can get more in due to the drawer configuration. The refrigerator is about 1 square foot bigger, or approximately 20% larger. And this makes a big difference! You can store an english muffin box or carton of a dozen eggs depth-wise into the fridge with room to spare. The refrigerator also features a 3rd pull-out produce drawer up top (in addition to the two produce drawers down below).
Installation Overview:
One of the hardest parts is physically getting the old refrigerator out. There are 6 screws under caps inside the fridge and freezer, but that’s not all. Winnebago “glued” it in with some black sealant and that’s what makes the removal difficult. Before attempting to remove it, be sure to first turn off your propane and disconnect the propane line at the back of the fridge from outside (using the access provided in the lower exterior vent). Insert a 3/8” flared plug to seal off the propane line (it won’t be used going forward). Then disconnect all wires at the back. The only wires you’ll reuse are the large gauge white and yellow 12v wires that were connected to the 20 amp DC fuse.
Removal of Wood Stops:
Winnebago installed some “stops” where the OEM fridge rested when it was slid all the way in. These prevent this deeper N2175 model from fitting, so the wood “stops” need to be removed (it’s straight-forward). Some other wooden panels toward the back of the compartment (exterior wall) are also in the way and they need to removed to make room for the depth of the fridge. It will be obvious when you do a test fit.
Outside Vents:
The 3-way refrigerator required the outside vents to allow a “chimney” for airflow to remove the heat and exhaust any fumes created by the propane burner. A compressor refrigerator, however, is typically installed in a sealed compartment with no venting to the outside. In fact, the refrigerator vents to the inside of the RV (same way that a residential compressor fridge vents into the kitchen and not to the outside). As a result, these two exterior vents/holes need to be blocked off. Most importantly, the back of the compressor fridge is not designed to be subjected to extreme outdoor temperatures, water, rain, blowing sand, etc. I went over-the-top and completely sealed and insulated both the top and bottom vents from the inside using custom cut pieces of wood finished with spray foam insulation (see photos). I’m sure there are simpler ways to do it, but I wanted to take the opportunity to seal any air gaps and maximize insulation in the part of the RV where it matters most.
Wiring and Fuse:
I used two WAGO connectors to connect the two leads from the refrigerator to the hot 12v power (large gauge white and yellow wires). This is the 12v power that was utilized when the 3-way fridge was operating on 12v while driving. Even if your old fridge stopped working on 12v, these wires are still hot (the wires weren’t the problem, it was likely the N3150’s circuit board).
The 20 amp fuse in the fuse box needs to be swapped out for a 15 amp fuse (per the N2175’s specs).
Power Consumption:
I was pleasantly surprised at how relatively little power it uses. When it’s cooling, it uses 4 amps DC. When off, 0 amps. And it has a 50% duty cycle (it’s on for about 30 minutes of every hour). So, in a 24-hour day, it uses approximately 48 amps. Provided you have solar replenishing your batteries during the day, you mostly need to be concerned with how much it uses overnight, which is about half of that depending on the time of the year and the length of the nights.
Now that my 3-way fridge is gone, I no longer have the 3 exterior exhaust fans and 3 interior fin fans + 1 blue light that I had running 24/7 before. My 3-way fridge was always using my batteries 24/7 because of these fans that helped it limp along, so it’s an extra benefit to have removed these small power draws completely.
Operational and Miscellaneous Details:
I keep the freezer on setting 3 of 3 at all times to keep the temp as close to 0° F as possible (which is considered the safe temp for frozen food storage). To keep my refrigerator between 35-38° F, it's typically set on 5/5 on a hot day and 4/5 on a cool day and/or at night. Nothing has accidentally frozen in my refrigerator so far.
In the refrigerator, the front edge of each shelf has a flip-up lip to prevent items from sliding off while driving.
Both the refrigerator and freezer doors have a removable black insert (face) that can be replaced with any material/color of your choice (ideally to direct match cabinets, etc.). The installation manual includes the specs and a template. I’m leaving it black as it looks modern and blends in well as-is.
LINKS:
Norcold N2175BPR: www.amazon.com/dp/B0CH1HTBN5
Spray Foam Sealant: www.amazon.com/dp/B01N21KQ4I
Propane Plug: www.amazon.com/dp/B09MYRKW4K