I have an extra refrigerator in my garage. I keep a refrigerator thermometer in the freezer (the freezer is at the top of the fridge), because that’s the kind of person I am. I like to know stuff.
Usually the temperature in the freezer is zero, which is what it should be. Sometimes it’s about 10 degrees below zero. The freezer is mostly empty. I keep ice cream treats in there (to make me think twice before I walk all the way out to the detached garage to get one), an extra loaf of bread, a few frozen entrees, blue ice packs, my dog’s Satin Balls. It is NOT crammed full ever.
Sometimes, like just a little while ago, I’ll go out there to get something and the temperature will be as high as 20. After standing there with the door open and pondering, it went up to 30. (What your mother said about standing with the freezer/fridge door open-- it’s true.) I turned the temperature dial down and then back up again (toward “colder”), just to make sure I could feel the thermostat kick on, and it did.
I went back to check just now, and it was down to 20. I hope it continues to head downward.
Meanwhile, I moved some actual food items into the freezer in my house just in case the temp continues to rise.
If I didn’t have a thermometer in there, I’d never know if the temperature was going up and down like that, as it doesn’t get warm enough for anything to thaw.
…Just went to check again and now the temp is just under 10. I assume it’s headed back down to zero or slightly below.
TL;DR Question: is it normal/okay for a refrigerator freezer to cycle between zero and 20 degrees throughout the day?
If it’s working correctly, obviously the contents themselves should never thaw. I don’t know if rising to 20 is considered normal. Perhaps your thermometer was close to the cooling element, which would get warm in the defrost cycle?
I’ve always kept a small bottle 1/4 filled with water in our freezers. I add water, then freeze them in an upright position. Once frozen, I lay the bottles on their side. If the freezer warms enough to allow the ice to thaw, then refreeze, the frozen water will tell me that this happened.
Yeah, I stand some ice cubes on a plate in the freezer for just the same reason. None of them have thawed. (Although after a while you have to add more, because they evaporate.)
A couple/few icecubes in a closed-up ziploc do the same thing.
If some time later they’re stuck together you had a mild thaw event. If sometime later they’re an amorphous lump of ice, you had a major thaw event. And, just for completelness, if they’re liquid now, you’re having a major thaw event.
Being in the ziploc they don’t tend to evaporate. And they can easily tuck into a cranny between other stuff in a crowded freezer. This is pretty standard technique here in hurricane country where the power may or may not have been out while you were away.
Most ice cream bars (and especially frozen fruit/juice bars) around here are deformed when they go into the freezer. Getting them home still in factory-fresh shape is tough. So their wacky shapes later aren’t real informative.
In most “normal” (i.e. not Sub-Zero) refrigerators/freezers, the thermostat is in the refrigerator, but the overwhelming majority of the cold air is blown into the freezer. The temperature dial in the refrigerator controls the thermostat and compressor, so changing that dial will affect the temperature in both the refrigerator and the freezer. The dial in the freezer just operates a damper that diverts more or less air into the refrigerator compartment, so adjusting that one only affects the freezer temperature.
If you regularly open the freezer door and/or put warm food in it, but not the refrigerator door, then the freezer temperature can rise a fair bit because the thermostat has no way to detect that. Conversely, if you regularly open the refrigerator door and/or put warm food in it, but not the freezer door, then the freezer temperature can drop well below normal because a ton of cold air is pumped into the freezer even though it’s the refrigerator that needs it. These effects can all be magnified if they happen to coincide with a defrost cycle too.
I graphed the temperature in my freezer awhile ago. It tended to swing quite wildly, even when the defrost cycle wasn’t running. It would get as warm as 20°F or so, then dive way down to -10°F, at which point the thermostat would switch off, and the cycle would repeat. So, 20-30 degree swing is normal.
IMO (recognizing this thread isn’t in IMHO) you’d have less temperature fluctuation in your freezer if it WAS crammed full. Every time you open the door of an empty front-door freezer all the cold air falls out and is replaced with warmer air, which can be quite warm in a garage.
If you have more thermal mass inside the freezer there would be less heat transfer every time the door is opened. Even old milk jugs filled with water would help. You have to freeze the water initially but that volume/mass of “cold” doesn’t fall out unless you are opening the door really quickly.
That makes sense. As long as I know the temperature fluctuation is normal, I’m okay. I only open it at most once a day (unless I’m investigating a problem) and some days I don’t go in there at all.
However, the freezer in my fancy-schmancy fridge in the house is crammed full, so what you’re telling me is helpful.
Are you using the refrigerator part at all, for liquid treats or something? CostCo has small chest freezers for two or three hundred dollars. They are a lot more efficient than a refrigerator/freezer and avoid the cold air spillage @pdhenry was talking about.
Well, I already own this one, so that’s an advantage.
I use it for some overflow things that don’t fit in the freezer in the house and that I won’t need right away.
During February power outages when we were told to boil water because our tap water had become unsafe, I dipped into a case of drinking water that I’d bought for my book club and had forgotten about. That was VERY handy.
TBH, I don’t care much about efficiency. The fridge just sits there in the garage minding its own business 99% of the time.
Everyone should remember that if are going to put jugs of water in your freezer that water expands when it freeze so you do NOT want fill the jugs all the way up. Otherwise they might burst.
The fridge just sits there in the garage minding its own business 99% of the time.