MikeH wrote:
Keep it in a cool place. Not only will the condenser be able to dump
heat easier in a lower ambient temperature, but the heat energy passing
into the freezer from the surrounding air in the first place will be
reduced as well.

I'd follow the manufacturers recommendations over bar-room science.
Fridges and freezers *do* have specific operating temperatures, and
it's fairly well known that fridges in particular can struggle in a
very cold environment. Freezers should have more leeway as they are
cooling to a much lower temperatures.

Frost-free freezers are less efficient than ones that have to be
manually defrosted. Ours has a heater element (about 300 watts) that
runs round the evaporator (the bit that cools the air inside the
freezer). Every eight hours or so the compressor switches off and the
heater is turned on for a few minutes. This melts the ice build-up on
the evaporator which then drains away through a pipe into a tray on top
of the compressor from where it naturally evaporates. Because the
heater is part of the evaporator assembly and is inside the freezer
compartment, inevitably that extra energy (300 watts for a few minutes
three times a day) than has to be removed when the compressor switches
back on again at the end of the defrost cycle.

How inefficient is a badly frosted-up unit, though? Generally, they
start to cut in more and more often to less and less effect as the
plates freeze up.

--
"Spice is the variety of life."