Hi, I have a Whirlpool ARC 7612 and I have recently had just the same problem.
This was fixed as follows:-
Unplug the fridge!!!
Remove the top two freezer section storage bins.
At the rear of the freezer compartment there is a plastic panel held in place with two cross head screws - remove these.
The panel will then kind of hinge down and can be extracted.
The blower fan can then be seen.
There is a circular channel that directs the air from the fan.
On the left hand side of this channel is an 'branch off' part that feeds the cold air up to the fridge section and this was blocked by a chunk of icy frost.
Removing this. :-)
Plug it back in and give it about 4 hrs to settle back down.
Fixed completely!!!! ;-)
As a separate note the bulb had popped for some strange reason . To remove it just pull it towards the rear of the fridge (after removing the cover first ;-)).
This is known as a 15W T-CLICK BASE T25 bulb btw.
Steve>>>
Steve
April 2008