I spent months trying to make a separate freezer compartment...crazy things like rectangular ducting for cold air to foam box structures...even cutting through the aluminum "skin" in attempt to prevent thermal conduction thus isolating a partitioned freezer...and NO GO. Just could not work. Now, when the fridge cycles frequently, such as hot ambient environment of 80-100 degrees, there is good freezing. But in low-cycling conditions (50-70 degree ambient temp), the two compartments tend to become more equal in temp due to longer time between compressor cooling.
Heh, I even tried adding low-power PC fan(s) for moving coldest air to freezer compartment.
But the good news is that after all this abuse over the 2.5 years I've owned it, even after I've giving up on the freezer compartment idea, the fridge still works perfectly well for its intended purpose...rugged environment refrigeration.
Note: My aim was to set the thermostat to "fridge temperatures" such as 34-38 degrees, and try to capture/isolate the coldest air into a freezer compartment which would stay below around 20-25 degrees.
But, later...after my failure...I realized a more successful design/operating approach might be to set the thermostat to "freezer temperatures" (not sure here...perhaps 15 - 20 degrees?), and then isolate off a LARGER compartment that is most prone to leaking out to the ambient environment (such as upper parts of the box), which would passively maintain refrigeration temperatures while the freezer temp is controlled actively via the thermostat.
Not sure if I'll ever test this second approach, but just thought I'd mention it along with my other hard-learned lessons.
