Today’s Fact or Fiction Question
Fact or Fiction? Outside temperatures can be too cold for an RV absorption refrigerator to cool.
*Paraphrased/condensed from this source.
Fact! Outside temperatures can be so cold that an RV absorption refrigerator will quit cooling.
I have been around RVs my whole life. I started working at my parents’ RV dealership, which was also a Dometic RV refrigerator service center, when I was 13. When they retired, my wife and I opened our own RV dealership and retained the Dometic service center for Seattle, Washington, and the surrounding area.
In all my years of being around RV refrigerators and servicing them, I had never heard of it being too cold for an absorption refrigerator to work, nor had a customer ever called to complain their refrigerator quit cooling during periods of sub-freezing weather.
It wasn’t until a friend bought a new travel trailer about six years ago that I began to learn about this subject. On the back of their refrigerator was a circuit that went up the back of the cooling unit controlled by a thermal switch. I couldn’t see what the circuit was powering, but I assumed it was a cooling fan to improve air circulation on hot days. It wasn’t until my friend called to report his house batteries quickly went dead after storing the unit in the fall that we researched the circuit further. It turns out, the thermal switch came on when the temperature dropped below 40° F, drawing a couple of amps of 12-volt power regardless if the refrigerator was turned on or not.
Calls to the RV dealer and manufacturer regarding the function of the circuit failed to provide a definitive answer. It was time to go to the ultimate source for anything technical regarding RVing. The late Gary Bunzer, the RV Doctor, provided the clue I was looking for. Via a Winter RVing entry on his website,
“The absorption refrigerator, however, may experience other issues. In extremely low temperatures, the refrigerator simply may not operate. The internal contents of the sealed absorption system include water, liquefied ammonia, hydrogen gas, and sodium chromate, the chemical used to protect the internal pipes from the corrosiveness of the ammonia.
“During a typical cycle, heat is applied by either an electric heating element or a propane burner. During the process of removing the heat from inside the refrigerator and freezer (the absence of heat is cold), the water and liquid ammonia are boiled and evaporated, then condensed back into a liquid over and over. And since water freezes at 32 degrees Fahrenheit … well, you can begin to see how very low temperatures can have an effect on absorption refrigeration.”
He goes on to say, “Temperatures below 10 degrees Fahrenheit probably will require some form of additional heat applied near the cooling core components at the rear of the refrigerator for it to operate properly.”
With this information, it became clear to me that the thermal switch controlled a 12-volt heating element attached to the cooling unit. It activates when the temperature at the rear of the refrigerator approaches freezing to keep the cooling unit functioning. An email to the manufacturer of the refrigerator (Norcold) confirmed this thermal switch and heating element were part of their “Cold Weather Kit.” This made sense as our friend’s trailer is considered a “four-season” RV.
In preparing for this article, I found an online copy of a Norcold owner’s manual and discovered the following on page 11. “A gas absorption refrigerator is not designed to operate in freezing temperatures. If the refrigerator is not equipped for low-temperature operation, and if the cooling system of the refrigerator is exposed to temperatures of 32° F. or lower for an extended period of time, the refrigerator operation may be disrupted. The refrigerator operation will resume when the cooling system of the refrigerator warms sufficiently. The refrigerator is equipped for low-temperature operation. The refrigerator will operate in temperatures down to 0° F with the cold weather kit provided if connected. Disrupted operation of the refrigerator, due to extended exposure to temperatures of 32° F. or lower, and any costs incurred to warm the cooling system of the refrigerator are not covered by the Norcold limited warranty. Please contact your local RV dealer for information about how to resume refrigerator operation or about how to equip your refrigerator for operation in freezing temperatures. Do not change the installation or the venting of your refrigerator. Refrigerator failures, which are the result of changes to either the refrigerator installation or to the venting, are not covered by the Norcold limited warranty. This kit supplies DC voltage to the heater any time the ambient temperature is low enough. Extended storage during cold weather will drain the vehicle batteries.” (Emphasis added by the author.)
This still leaves me wondering why I had never heard of this problem in the past when I was actively involved in servicing and repairing absorption RV refrigerators. Has it only recently become a problem when RV refrigerator manufacturers updated their cooling units to be more tolerant to off-level operation? Or is it because I live and work in the Puget Sound region that has temperate winters and rarely experiences extended periods of below-freezing weather? Your comments and theories are appreciated.
Now, some questions for you:
- Is there a reoccurring half-truth you keep seeing online that you would like to see addressed?
- Were you taught something by other RVers that turned out to be bad advice?
- Have you recently read something that left you wondering, is that true?
- Do you know something to be true, but none of your RVing friends believe you?
Please share your comments using the comment box below and we will do our best to provide the facts in a future Fact or Fiction entry.