[Updated: added some info about what I found in the bottom housing, as well as the sound of the fan in the freezer.]
I've got a GE PFSS2MIXASS Fridge (Double doors on top, freezer on bottom). A couple of days ago, we noticed a few things were frozen in it. Today, I looked into it more and realized that the bottom is way too cold (24 degrees) while the top shelf is way too warm (54 degrees), while the fridge thermometer itself is reading 42 degrees. It's not just the stuff in the veggie drawers at the bottom that is freezing - even milk on the bottom door shelf is freezing.
I took out one of the bottom drawers to see if that would improve circulation, and it doesn't seem to affect things (though it has only been 5 or 10 minutes). So it would seem that the circulation is the problem. I've had circulation problems in the past when the fridge was crammed full of food, but our fridge isn't very full - maybe half full.
My understanding is that the cold air in the fridge actually comes from the freezer, and that there's a thermostat controlled device that opens/closes that pathway. It appears that these vents are in the back bottom of the fridge, behind the drawers, which would explain why they are so cold. But given that the top isn't very cold, it makes sense that it would keep bringing in cold air, but that cold air all seems to come from the bottom. Here's a picture of the bottom vent that you can see now that I've removed the bottom right veggie drawer.
There is a small vent towards the top of the fridge in the back (labeled "climate keeper"), but I don't feel any airflow coming out of that. Is that supposed to have air coming out of it? Here's a picture of that upper vent:
It's hard to tell where that would come from, though there is some sort of structure in the center behind the two bottom drawers that could possibly serve as an inlet for air to go up and out through the upper vents. Here's the center of the bottom of the fridge where the inlet could possibly be - there's a gap around it though no explicit openings:

Is there a fan in there that should be circulating air up (that is possibly broken)? Or is it just natural convection currents that should be moving air around inside? In the parts list, I don't see anything obvious that would circulate the air in the fridge compartment.
Update: So I took the other bottom drawer out and was able to unscrew the cover on the bottom housing. After taking it off, there was a styrofoam block there that seemed to direct air from a vent on the bottom (coming from the freezer?) to some holes in the back (that go up to the top shelf vent?). Interestingly, it also has a black device in it that has a smooth surface and is plugged in to a power jack. Not sure what that is, but it's not a fan. Here's a picture with the styrofoam block removed:
And a photo of the block and black device inside:

Update: I'm not sure if it always did this, but when I opened the freezer and listened to the fan, it seems to be constantly running but occasionally "hiccups" - stops for a fraction of a second and then restarts. I'm not sure what controls this fan (the temp of the fridge?), but it would make sense if it was constantly running since the fridge thinks it should be at 39 degrees, but is reading 50 degrees. Not sure why it seems to stutter occasionally.



