If the days were at 20 below, I'd just unplug it, maybe crack the door.
Although, 40F is COLD where I am, so maybe you shouldn't listen to me anyways...
No, a normal residential type fridge CANNOT actively heat its interior.
However I think I can explain Reinbeau's ice cream.
AFAIK most refrigerators' thermostats read temperature in the fridge (not freezer) compartment, and that's what determines whether the compressor runs to provide further cooling.
If ambient temperature is, say, 35 F, then as far as the thermostat is concerned the fridge is already plenty cool and the compressor needn't do a thing. But since the compressor jointly cools the fridge and freezer compartments, if it ain't running to cool the fridge part, it ain't running to cool the freezer part either, so the freezer compartment will equilibrate to that 35 F temperature, which is above the freezing point of ice cream so it will melt.
I do not know how many or which refrigerators might have separate thermostats for the fridge and freezer parts. Without a separate *compressor* (or coolant circuit, anyhow) I do not see how that could keep both fridge and freezer both at proper temperatures when ambient temperature is low, however. Either one will be too cold or the other too warm, because of compressor run-time.
Basically, you can certainly keep a fridge or freezer in an unheated garage, but when the air temperature dips below freezing for more than a short while, anything in your 'fridge' compartment will freeze. So, take out the glass bottles and carrots
(e.t.a. - the more trouble-free version is to keep a FREEZER, like a unit that is *only* a freezer, in the unheated garage. Nothing will go wrong; the colder the garage is, the less electricity you will use, potentially none at all for a few months if you live waaay far north. Avoids the ice-cream-melting problem altogether, b/c no fridge compartment is involved)
So, a dedicated freezer, or a 'beer fridge' where you didn't really use the freezer, is fine - but not the combo, unless they've got separate compressors. Most home fridges only have one, so, as I said, don't plan on using the freezer in an unheated area where the temps will fall below freezing for a period of time. Maybe my 'heater' term was wrong, but I did know it had to do with the fridge temp reaching the freezer, I just didn't articulate it properly. Thank you, Pat, for spelling it out so clearly.
Wow, I was gone for only a few hours and look at all the replies!! Thanks, everyone! Great explanation, Pat!
The fridge I just got for my second fridge has no freezer compartment at all. I wondered why, maybe this is why. Maybe it is actually designed to go into an unheated space.....
I want to use it for fermenting and for aging cheeses.....now that I have it, it is time to branch out into the year-long aged cheeses, like romano! But my cellar gets too warm in the summer, hence the fridge, worry-free steady temps. Besides, I want to fill my cellar space with squash and pumpkins and such this fall.
So my conclusion is that it would not work well in the unheated space because when the temp dips down below freezing, even below zero, everything in my fridge will freeze. A night or two would be ok, but we can have WEEKS here.