Life on the Road with a DC Compressor Refrigerator

Keeping Your Cool

The Dometic CRX Series is a popular choice in truck camper refrigerator freezers. The 12 volt option and ability to adjust fan speeds according to ambient temperature make it ideal for applications where solar is used and battery charge conservation is a concern.

A variety of sizes is reflected in the numeric naming of the series. Smaller versions are said to have the ability to remove the freezer compartment for 100 percent fridge, keep it for a fridge-freezer combo, or run with ‘all freezer. We have the CR-110, the second largest model that Dometic makes with a permanent freezer built into the top part of the unit.

Trial by Fire

We’ve been on the road for almost three years in our Nimbl/XPCamper, and have put our CR-110 through its paces in some fairly harsh environments. Refrigerators do not like confined spaces, heat, or being shaken around. Unlucky.

From the steak-searing heat of New Mexico to the brutally 100 degrees F and 90 percent humidity nights spent in Baja, the fridge had a baptism by fire. Bouncing around over various trails just added to that. Moving through Central America ensured things certainly didn’t get any better. Things started to go wrong, but—spoiler alert—the refrigerator has been a great choice for us so far.

Boiling in Baja

Dometic CR-110 noise is fairly minimal. A slight hum when running, a marginally louder hum when starting up. Neither loud enough to be noticeable unless it is particularly quiet, and certainly nothing like keep-you-awake annoying. If I was going to give it a score out of 10 for “quietness” I’d give it an 8 and, considering I sleep 1 metre away from it, I think this is a very reasonable unit.

Power use is not bad for a bigger fridge. The 12 volt setting—it can use AC too—is rated for just over 6 amps. In reality that figure is not going to help much because, depending on ambient camper temperature, the fridge will cycle on and off more or less frequently and for longer or shorter periods. We find that after an eight hour night at around 72 degrees F we’ve used maybe 22 to 24 amps bringing us in at just under 3 amps per hour. This increases when things get hot and humid.

Its a fridge. Its a freezer. It makes our things cold or it makes them very cold and hard. My excitement over a fridge should be almost zero. It is. Which is testament to the fact that it just does what it is supposed to with a minimum of fuss. If there is a wonderful, almost glowing, review of a fridge it should be that you pay absolutely zero attention to it, whatsoever. A benign addition to your camper. You don’t find yourself short of space. You don’t find yourself losing all your expertly captured solar. You don’t find your food has spoiled and you don’t find your frozen items semi-defrosted. The Dometic CR-110 is a reasonable testament to just how dull a good fridge should be. I like adventure, experience, excitement—just not from my fridge.

We do/did have the occasional issue though. A few things just to remind us that life on or off the road means that even shrinking violets seek attention sometimes. So for those with, or looking at, a Dometic CRX DC compressor refrigerator; read on.

Issue #1

A cramped install and Hades weather conditions meant the back of the fridge got incredibly hot. Our cutlery drawer is directly above the fridge. Occasionally the cutlery was almost too hot to touch and I am sure at one stage Claire was considering baking a lasagna in there.

One day we stumbled across a marvelous empanada baker in the jungle of Costa Rica. It was called El Hornito. They had free decals. So, we called our fridge El Hornito, which translated means “The Little Oven.”

We couldn’t do much about the install location, but the existing fridge ventilation was pitiful. A single slatted chrome vent in the camper shell, located under the counter just behind the fridge, provided a slim escape route for the hot air coming off the fridge compressor. When camped it was bad enough, but we have a pop-up camper, and when we drive the camper shell lowers over the vent, closing it off. Oh, and the Webasto X100 stove is in the same airspace, right next to the fridge. They should have popped the sun in there too for good measure.

I knew a fan of some kind was the answer. I also knew I wanted one that was whisper quiet and could be speed controlled to reduce power use. The fridge itself already boasts a fan that adjusts to ambient temperatures, but these ambient temperatures were way too high.

I ran with a Noctua Redux PWM fan with a small Noctua FC-1 PWM Controller. The fan uses just 0.08 amp hours on  the “max” setting. Solar frugal to say the least. Various fans sizes are available, my existing vent hole was a circular 90mm, so the 92mm option was perfect for me.

Installation of the fan was easy. I spliced into existing 12 volt wiring and slapped the fan up against the existing slatted vent. It works like a charm and is inaudible even on “max speed.”

I have to physically switch the fan on and off, which I can do from inside the camper with a switch on my control panel. I think some kind of thermostat hidden beside the fan would be ideal.

Even with the camper shell lowered, there is enough gap for air to be expelled nicely.

Issue #2

A small, but annoying design flaw has seen me digging out the Loctite Super Glue on more than one occasion. A small bottle of adhesive that I hate using, mainly due to the “No glue. ALL THE GLUE!” delivery method these tiny tubes favor when squeezed by my oversized paws.

I also hate brittle plastic. Especially when used in areas where brittle plastic is allowed to take full advantage of its main hobby of shattering whenever possible; and the CR-110 does not disappoint. Placing an opaque blue lid above the door’s top shelf; perfectly positioned to explode the minute you shut the door having forgotten to lower the lid.

Maybe a rubber edge to the lid. Maybe no lid at all. Either of those option would leave me without the fun of using super glue. One end of the lid now a cobweb or glued cracks. You can simply remove the lid, but where’s the fun in that?

Issue #3

Ants. Bastards! They like food, the like holes in the camper. They love holes in the camper that lead to food. Strangely, this has only been an issue once. Maybe the cold kept them away.

The fridge has a drain hole in the bottom center of the floor. This connects to a 90 degree ridged elbow under the fridge, which allows a small rubber hose to be attached, draining spills or whatever might need draining to wherever you want it draining. A plug is supplied if you simply want to block this hole off. As the fridge contains liquids and we off-road a lot, we leave the drain open.

A couple of cold-resistant ants were scuttling inside the fridge. Closer inspection revealed a few warmer blooded of their friends hanging out in the drain tube itself. A dose of Raid spray and a water rinse sorted this out. Something to keep an eye on.

Issue #4

We have only ever had one problem with the fridge not working. Every now and again we would get a low voltage error. The blinking display inside the fridge indicating “Supply Voltage outside of set range.” A problem that kept repeating itself, despite resetting the fridge by turning it on and off and checking battery levels.

I am not electrician, but I used a multimeter to check voltage levels at various points, from the battery to the fridge. I found that one wire had been zip tied to a particularly hot part of the compressor. Possibly in the fridge factory. Possibly at the camper factory. The heat seemingly killed the voltage on the 12 volt supply cable. I removed the zip-tie, secured that cable elsewhere, and the fridge has worked perfectly ever since.

Issue #5

My last fridge tip—and the biggest—involves the fridge door. It is not a great design. Why is nothing ever a great design?

You can save yourself a cracked fridge hinge, an opening fridge door, a freezer that needs defrosting and warm beer when you get to your campsite. All it takes is a bread tag inspired piece of cutting board (other solutions may be available).

Fridge doors hold a bunch of heavy bottles, heavy cartons, or heavy whatever. It’s the law. The fridge door is likely heavier than your fridge shelves, maybe even heavier than your truck engine.

The door has raised plastic “studs” that are molded to the frame. There are one at each side on the top, one at each side on the bottom, so you can reverse the door opening to suit different vehicle layouts if you wish. These raised plastic studs mate with a metal pin. Dropping onto a metal pin at the bottom, with another metal pin inserted at the top. The metal pins are on a bracket attached to the main part of the fridge and allow the door to swing open and closed.

Here’s where the bad design comes in. There are only two points of contact for the door. The plastic stud at the top. The plastic stud at the bottom. The problem is that ALL of the weight is on the bottom plastic stud. Just 3mm of raised plastic which is formed out of the brittle material base of the door. Take all of the aforementioned door weight. Place it on top of a brittle plastic stud. And now bounce it up and down as you drive. Or hammer it up and down as you drive off-road.

So, what happens?

• The area around the plastic stud cracks.
• The stud starts to retreat inside the door
• The door then starts to drop
• The lock/catch at the door base starts to stress, then breaks
• The door continues to drop as the plastic stud cracks further
• The door is now so low the top catch no longer catches
• The door is now only held shut by the vacuum seal
• The door is also held shut with a pillow while traveling

This happened over a four- or five-month period as we noticed the door and door catches get progressively “weirder” to use/catch than they were before. Use something every day and you notice small changes.

The Fix:

I was going to remove the door and glue the stud. But that would require removing the fridge, removing the door and likely being left with the same issue further down the road. I needed something the same height as the the stud (3mm), but with more surface area to spread the load over a wider area. Some kind of hard washer.

I grabbed one of my trusty cutting boards that I seem to use to fix anything and created a “bread bag closure” shape. When inserted, the small channel pushes past the stud, which then locks into place when it gets to the hole of the same size (12mm). It spreads the door load over a larger area than the stud, and keeps the door raised to where it should be. The door now opens smoothly and the top catch actually catches.

For those whose door is intact. This is a super easy way of ensuring it stays that way. If your stud has cracked and dropped. It’s an easy fix. The plastic “bread tag” may well wear down over time. In which case I’ll throw another one in. But it won’t crack and doesn’t require the sweat-inducing task of removing the fridge.

As with all prototypes, I had not made it pretty. As with all working prototypes, it’s going to stay where it is regardless of what it looks like. Next time I will make a 1-inch round disc to start with rather than square. That will “pretty” things up quite a bit.

Final Thoughts

The Dometic CR-110 is a great DC compressor refrigerator that has lasted us well over our three years in the road. It’s relatively quiet, relatively frugal on power, and does what we need it to do. It also holds a surprising amount of food and drink.

The door hinge was the biggest issue, and adding the “bread tag” should relieve the stress on the plastic stud and ensure that the problem never arises.