Any issue I should be aware of if the OAT (unheated trailer) is 25°F? As the trailer warms inside, and fridge warms up, will propane automatically fire and start functioning?

If I understand your question...... If the refrigerator is turned on and set to propane, you have propane and 12v to the fridge it should operate normally. When ambient temperature rises enough that the interior of the fridge warms above the thermostat set point the fridge will fire up the propane.

We kept all our previous TT's with ammonia absorption RV gas-electric refrigerators running 24x7x365, on both gas and electric (depending).What we found out, after doing this for almost 20 years, is when the ambient temperature around the refrigerator gets colder and colder, the refrigerator has to run less and less. When the outside temperature get's colder than the inside, there is a point when the refrigerator will not run at all. Why should it? The inside is already cold, below the set temperature. Now this worked ok, except for when the ambient temperature got around to 38 to 28 degrees. It at that stage the refrigerator doesn't need to run, to make things colder. It's already cold.The problem is ... the freezer! The ambient temperature is still above freezing slightly, but the refrigerator is now colder than the setting. Result: the freezer doesn't run. So if you have nothing in the freezer, no problem at all. But if you anything that you don't want melting ... like ice cream ... well, the freezer is now not running either, but still not cold enough to retain things in a frozen state.Once the inside of the freezer reaches 32 degrees or less, then things will start staying frozen again.So, it will be fine if you have nothing in the freezer. Otherwise, you have to leave some heat on in the camper so the refrigerator warms up enough to run.Now, what about household refrigerators and what about Coca-Cola vending machines? What keeps them from freezing in the dead of winter sitting outside? They actually have heaters built in them that will keep things from freezing when the ambient temperature drops below freezing.

DutchmenSport wrote:We kept all our previous TT's with ammonia absorption RV gas-electric refrigerators running 24x7x365, on both gas and electric (depending).What we found out, after doing this for almost 20 years, is when the ambient temperature around the refrigerator gets colder and colder, the refrigerator has to run less and less. When the outside temperature get's colder than the inside, there is a point when the refrigerator will not run at all. Why should it? The inside is already cold, below the set temperature. Now this worked ok, except for when the ambient temperature got around to 38 to 28 degrees. It at that stage the refrigerator doesn't need to run, to make things colder. It's already cold.The problem is ... the freezer! The ambient temperature is still above freezing slightly, but the refrigerator is now colder than the setting. Result: the freezer doesn't run. So if you have nothing in the freezer, no problem at all. But if you anything that you don't want melting ... like ice cream ... well, the freezer is now not running either, but still not cold enough to retain things in a frozen state.Once the inside of the freezer reaches 32 degrees or less, then things will start staying frozen again.So, it will be fine if you have nothing in the freezer. Otherwise, you have to leave some heat on in the camper so the refrigerator warms up enough to run.Now, what about household refrigerators and what about Coca-Cola vending machines? What keeps them from freezing in the dead of winter sitting outside? They actually have heaters built in them that will keep things from freezing when the ambient temperature drops below freezing.Your premise is totally wrong. As the Refer box is INSULATED, it does 2 things. It keeps the outside ambient heat from getting to the inside box and it does the SAME when in freezing temps. OUTSIDE freezing temps will NOT cool the Interior of the refer. Granted, it will cool easier when you do not have to battle the outside HOT in warm/hot climates. Now, for RV refers, COLD WILL degrade the ammonia process. You will be OK down to about 25 degrees. BELOW that you need to install a 60 watt light bulb at the outside rear of the cooling unit to warm up the area. Once you get below about 10 degrees, the RV refer will not function, even with a light bulb. Doug

There are ways to make the fridge work at -37C (-34 f).Norcold makes a cold weather add on kit.Restricting air flow and a 60 watt bulb controlled by a thermocube also work.See the thread in full time RVing called "winter camping". There are a host of cold weather modifications that may be done.

I’ve run RV fridges at -30F. But that was in Canada where it’s a dry cold. :)

running fridge in cold weather? | Good Sam Community

ScottG
Nomad
Dec 12, 2019
mchero wrote:
Coke and Pepsi machines do NOT have heaters in them. Been maintaining these machines for the last two years.

Maybe the ones you worked on didn't but a quick Google search revealed that many do.
wa8yxm
Explorer III
Dec 11, 2019
Another low ambieent temp trick.. Some models havew a LAT switch. what does it do?

Well if you were to insert a photo cell and measure it you'd find that the light does NOT TURN OFF. the small light adds heat to the fridge causing it to run and kwep the freezer..froze.
MDKMDK
Explorer
Dec 11, 2019
Add refrigeration in different climates to the list of topics that draw the most in terms of conflicting expert opinions. Batteries and charging and solar are already on it.:C
mchero
Explorer
Dec 11, 2019
Coke and Pepsi machines do NOT have heaters in them. Been maintaining these machines for the last two years.

We full time in our rig. Norcold 4 door worked w/o issues even when temps well below freezing this6 last winter.
I restrict the vents on the outside cover during winter.

Previous poster mentioned the mess exploding cans create, that's nothing compared to a ice cream freezer loosing power, ice cream melting all over the inside then power is restored freezing the melted mess.
Time to break out the steam cleaner!
pianotuna
Nomad III
Dec 11, 2019
In weather cold enough the working fluid may gel. If it does it may cause a blockage. If you are lucky the blockage may be "jarred" free. If not, you get to replace the fridge.
ScottG
Nomad
Dec 11, 2019
DutchmenSport wrote:
We kept all our previous TT's with ammonia absorption RV gas-electric refrigerators running 24x7x365, on both gas and electric (depending).

What we found out, after doing this for almost 20 years, is when the ambient temperature around the refrigerator gets colder and colder, the refrigerator has to run less and less. When the outside temperature get's colder than the inside, there is a point when the refrigerator will not run at all. Why should it? The inside is already cold, below the set temperature.

Now this worked ok, except for when the ambient temperature got around to 38 to 28 degrees. It at that stage the refrigerator doesn't need to run, to make things colder. It's already cold.

The problem is ... the freezer! The ambient temperature is still above freezing slightly, but the refrigerator is now colder than the setting. Result: the freezer doesn't run. So if you have nothing in the freezer, no problem at all. But if you anything that you don't want melting ... like ice cream ... well, the freezer is now not running either, but still not cold enough to retain things in a frozen state.

Once the inside of the freezer reaches 32 degrees or less, then things will start staying frozen again.

So, it will be fine if you have nothing in the freezer. Otherwise, you have to leave some heat on in the camper so the refrigerator warms up enough to run.

Now, what about household refrigerators and what about Coca-Cola vending machines? What keeps them from freezing in the dead of winter sitting outside? They actually have heaters built in them that will keep things from freezing when the ambient temperature drops below freezing.

This is dead-on correct and well written although I had not heard about resi units having heaters.
rexmitchell
Explorer
Dec 10, 2019
DutchmenSport wrote:
Lesson learned when 12 cans of Coca Cola exploded in our refrigerator one winter when the temperature inside the trailer was negative 15 degrees and the outside temperature was negative 20 degrees. It didn't take much time for that cold to penetrate to the inside of the refrigerator.

The mess took about 3 hours to clean up once I found it! Lesson learned, when winterizing ... make sure EVERYTHING that has liquid is removed from the camper! Refrigerator included, even if it's left "on".

I had the same thing happen except in a car in the Texas summer heat. Black Volvo with white cream interior. 12 pack of cokes exploded. I wanted to sell that car after looking at the headliner.
MDKMDK
Explorer
Dec 10, 2019
DutchmenSport wrote:
Lesson learned when 12 cans of Coca Cola exploded in our refrigerator one winter when the temperature inside the trailer was negative 15 degrees and the outside temperature was negative 20 degrees. It didn't take much time for that cold to penetrate to the inside of the refrigerator.

The mess took about 3 hours to clean up once I found it! Lesson learned, when winterizing ... make sure EVERYTHING that has liquid is removed from the camper! Refrigerator included, even if it's left "on".

What about RV antifreeze?
Engine oil?
Bottled water? (it could freeze, but clean up is a breeze :B)
DutchmenSport
Explorer
Dec 10, 2019
Lesson learned when 12 cans of Coca Cola exploded in our refrigerator one winter when the temperature inside the trailer was negative 15 degrees and the outside temperature was negative 20 degrees. It didn't take much time for that cold to penetrate to the inside of the refrigerator.

The mess took about 3 hours to clean up once I found it! Lesson learned, when winterizing ... make sure EVERYTHING that has liquid is removed from the camper! Refrigerator included, even if it's left "on".
noteven
Explorer III
Dec 10, 2019
I’ve run RV fridges at -30F. But that was in Canada where it’s a dry cold. :)