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Can outside temperature be too cold for an RV refrigerator to cool?

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.

Answer:

Fact! Outside temperatures can be so cold that an RV absorption refrigerator will quit cooling. 

RV in sub-freezing weather
Frosty Campout

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.

##RVT1087

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Billinois
14 days ago

I question the belief that tires should be replaced at 3-5 years. Even for travel trailers this seems excessive.
In the 7 years I owned my TT I never had an issue with tires. With my motorhome I changed my tires at 7 or 8 years. Michelin states their age-out limit is 10 years.
When did the recommendation change and who says change them out at 3-5 years?
Seems like an anecdotal myth to me.

Les McGuire
14 days ago

I am in between RV’s, my intent is boondocking with a small motorcycle on a hitch carrier, something light, maybe 300#. I’m on a budget and thinking of an older class c, maybe 22′-24′. Is this do-able? Any recommendations? I encourage all comments, even those who may agree the motorcycle idea is a bad one.

Billinois
14 days ago
Reply to  Les McGuire

Most receivers on Class C motorhomes are rated at around 350lbs tongue weight. That might sound fine, but the problem is how they are mounted to the frame. The one on our Winnebago 26A was bolted on.
We were towing our Subaru and hit a huge dip in the pavement (at 65mph) on the interstate, somewhere in Texas. When we came up out of the dip the resulting force bent the receiver down about 2 inches. You won’t be towing but you will be carrying a motorcycle, plus the carrier. If you do this you should take the motorhome to a welding shop and have them box in and weld the receiver to the frame. It cost me about $300 but the welder guy said, “it’ll never bend again. Don’t be afraid to use it”.

Admin
Diane McGovern
14 days ago
Reply to  Les McGuire

Hi, Les. Sorry for the long delay in responding. I was going to look up a link this morning for you but got sidetracked and just now remembered I never got back to you. You’ve asked this question about Class C’s and motorcycles in a post about RV refrigerators, so I’m not sure how many will reply to you (although I see Billinois did [thanks!]). But I think you would get more responses if you go to our Facebook Page for RV Advice: https://www.facebook.com/groups/rvadvice/ and post your question. I bet you’d get some helpful advice there. Good luck! 😀 –Diane at RVtravel.com

Tom Suess
14 days ago

Last summer, I was boondocking and happened to be under a large storm containing a lot of energy. My cell phone started populating with multiple SEVERE storm warnings for flood, dust, and wind.

I left my truck attached to my 20 foot single axle travel trailer, As the wind increased force, and the sound of wind entering the trailer went up about three octaves, my trailer started swaying to the point that the metal mounting plate on the bottom of my microwave completely broke off, and I thought the trailer was going to be on its side.

Obviously, the best situation is not to be located under such a large amount of weather energy, but if I am, what is the best way to proceed? Question: For a single axle relatively light trailer, is it best to

1) Leave the trailer connected to the tow
vehicle for one extra point of contact?
OR.
2) Unhook the tow vehicle and park it next to the trailer to use it as a tool to block some the wind contacting the trailer?

Dennis Johnson
14 days ago
Reply to  Tom Suess

If the wind is fairly steady from one direction, I leave the rig hooked up and face the truck. into the wind. This helps, in my opinion, to create airflow similar to what you face driving down the road. You may well rock a little because of wind variations.

Jim Johnson
14 days ago

Keep hearing the myth that a grey water tank gate valve can be left open when a RV is seasonally stationary.

Not so. Grey water has suspended solid waste (food, skin, hair, soap scum). It will filter out to the sides of the holding tank as the intermittent water flows toward the gate valve. And without regular large water volume flushing, this crud solidifies and becomes at least semi-permanent – – that is after it rots and stinks.

DJ Napora
15 days ago

We know that in a motorcoach, the rear wheels should stay on the ground, but after leveling “ is it ok to have the front wheels off the ground?”
Fact or fiction?

Bob p
14 days ago
Reply to  DJ Napora

The general consensus is the front wheels need support, but don’t ask the people in the park we stayed in in Dade City, Fl. The site was so unlevel front to back they had precut 2X12 pads to put under leveling jacks so our MH could be leveled. Our front tires hung in mid-air 8” off the ground. When I backed in far enough to keep the wheels on the ground I was told I had to be X number of feet away from the power source, so back forward I had to go. That site should never have anything larger than a 25’ trailer.

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