In article ,
Bob Minchin writes:

No Freezers only have one compressor. Some expensive, properly designed
fridge freezer have two but most FF have one compressor and arrange
through a design compromise to share the cooling circuit between one
cabinet at about +3 degrees and the other at -21 degrees .

I think this info might be a bit out of date. There are now
FF's with a single compressor but still with independant
control using a solenoid valve which allows the refrigerent
to be directed.

The older (and possibly current cheaper) units rely only on
a thermostat in the fridge, and based on a temperature of
something like 14C ambient minimum, they know the compressor
will operate on sufficient duty cycle to keep freezer cold
enough. If the ambient drops below the minimum for that FF,
then the fridge won't need as much cooling, and the freezer
will start to warm up.

The skin cooled ones are my favourite for garages as the outside of the
case is warmed regularly and this dries off the demon condensation which
the other two types do not and which tend to rust the outer casing. This
is only cosmetic but soon looks crap.

Can also drip in the floor, and depending on the covering,
damage it. Uprights often have anti-condensation heaters
around the door seal, where most cold leak out ;-)

--
Andrew Gabriel