Cool… and wireless

Maintaining the right temperature* (33 to 39 °F) in our Airstream Safari’s 5.0 cu. ft. refrigerator is important to keep food from spoiling or freezing.  The cooling process of RV absorption refrigerators* is different than compression driven, household refrigerators.  Absorption refrigerators have a relatively low coefficient of performance, which makes it especially important to keep the RV refrigerator in peak operating condition.  To properly monitor our refrigerator, we need to know the temperature of the inside of the refrigerator at all times without opening the door, which would result in a temporary loss of cold air and decreased efficiency.  Our first refrigerator thermometer in 2007 had a thermistor probe on a wire that connected to a digital display panel mounted on the refrigerator door and served us well for 6 years.

When the thermometer’s probe failed to register temperatures accurately last spring, we did our research and selected the AcuRite Refrigerator/Freezer Wireless Digital Thermometer, #00986.

DSC_0095 AcuRite Wireless Thermometer

This thermometer comes with a digital LCD display on the main unit (receiver) and two remote sensors, labeled 1 and 2.  I chose to use sensor #1 to monitor the refrigerator temperature and sensor #2 to monitor the room or outside air temperature.  The image below shows the thermometer sensor on the middle shelf and the refrigerator’s thermistor probe on the right side, which I raise or lower to maintain the right temperature as noted above.

DSC_0004 Wireless sensor & thermistor

The main unit has a strong magnet on the back that firmly holds it on the side of our stove exhaust fan/light fixture.  The sensors send out a strong signal, and at home, I found that I could bring the main unit and sensor #2 into the house and monitor the house and trailer refrigerators at the same time!  The image below shows the temperature readings of the trailer refrigerator (34 °F) and the outside air (39 °F) during an evening last April while camping at William Heise County Park.

DSC_0010 Main unit receiver

Although we do not use the alarm feature, we do like the main unit’s display that shows the lowest and highest temperature since it was last cleared.  We have found that there are many variables that affect the refrigerator’s temperature, including the size, amount, placement and temperature of food going in.  Knowing the highest and lowest temperature since the display was last cleared helps me to position our refrigerator’s thermistor for the optimum temperature range.

We have solar panels that work best when we are in a campsite that gets full sun most of the day, which provides additional incentive to find ways to help the refrigerator work better,* such as propping the outside vented doors open with clothes hangers to increase heat dispersal.

DSC_0004-2 Fan, switch, & hanger

Our custom-built Airstream trailer came with with two factory-installed solar panels, and we were glad we also chose the Full Awning Package, which provides awnings on three sides…

DSC_0029 All awnings & vents open

And helps us with our goal of keeping cool, even in the desert.*

*This is a link to a YouTube video.


  1. Bill D. says

    Thanks MaryD for your comments… Our feasts while camping will resume in the fall when the weather cools down!

    Note to readers: In 2004, Mary and Rick bought a 1961 Airstream Safari, named “the Toaster”. In 2005, they began their blog, “Tales of the Toaster“, as a way to share their renovation experiences. Additional help came from Frank’s Trailer Works in 2012. Frank beautifully restored their trailer to its 1961 vintage appearance. See Frank’s loving story and photos of the restoration of the Toaster here.

    Now “Tales of the Toaster” is Mary and Rick’s “way to also share our road adventures with family, friends and others who are just plain attracted to vintage living.”

  2. insightout says

    Bill D.

    This entry qualifies as a chapter in the “Newbie Guide to Airstreaming”.
    (alert to author/publisher, R.Luhr)

    We’ve ordered an Acu-rite and also adopted your hint to leave the outside hatch open to allow more circulation. Our aging 1986 unit has
    a small fan in the lower fridge compartment, but it has never functioned, nor have I ever bothered to trace the problem. It’s the size of a toy, like a dime store, plastic fan-on-a-stick we waved in the wind as kids. I’d rather have something ≋ to a wind tunnel machine.

    Green egg salad never bothered me (nor Dr. Seuss) as most bacteria are quite harmless, a medical tenet my wife has never embraced. What does bother me is a Klondike ® bar served at room temperature.

    Lynn also informs me that dime stores are now called dollar stores.

    Thanks once again for a useful, well-written, and very cool documentary. You may have solved a problem Jack and I have confronted for several years.

    Warm beer.

  3. Bill D. says

    Ha… I remember when they were called “five and dime” stores, and “five” referred to 5¢ (ever notice that there’s a dollar sign, but no cents sign on your keyboard?… I have to use “Option+4” to make the “cents” sign make sense on my Mac!)

    Thanks, Dr. C, for sharing your experience and Lynn’s insight.

    BTW, AcuRite recommends using Lithium batteries (AA & AAA) for this thermometer as they will last longer and work better than alkaline batteries in cold temperatures.

    Jack has good taste… I prefer my beer cold, too… I really enjoyed the icy/frosty bottles of San Miguel served in Olongapo when I was in the Navy… and, like the five and dime stores, those were the days!*

  4. Bill D. says

    Author’s note:

    A reader wrote: “You may want to take the batteries out after each use. We found the dampness that resulted from the change from cold to normal temps accelerated battery failure and/or mildew in the battery compartment.”

    Here is my response:

    “Our trailer refrigerator has been on and in use since we got it over 6 years ago, except for very brief defrosting periods about every other trip or about every 2 months. When I defrost the refrigerator, I place frozen food items in a nearby cooler during the 20 minutes or so of defrosting while blowing room air into the refrigerator by using a fan set on the lobster sink.

    I’ll take your suggestion, though, and place our refrigerator thermometer sensor (#1) in the cooler with the frozen food while defrosting (to prevent condensation from forming on the batteries and/or in the battery compartment).

    As noted in my blog article, “Cool… and wireless”, I initially did some tests and moved the sensors around to different places, but now one sensor stays in the refrigerator and one stays on or near near the magazine rack to detect the room air temperature of the trailer.

    Also note that we only use lithium batteries for this thermometer (Wikipedia article states lithium batteries last longer than alkaline batteries). The main unit (receiver) takes 2 “AAA” batteries and each wireless sensor takes 2 “AA” batteries. AcuRite’s Setup Instructions recommend that lithium batteries be used in a sensor that is placed in the freezer compartment because “Lithium batteries function at lower temperatures better than alkaline batteries.”

    We have not had problems with our original lithium batteries and have not had to change them since we started using this thermometer last April.”