sorry but I doubt bill's advise is correct.
If the evap coil was frozen then you would also notice a rise in freezer tempreture.
You have not even said it is a FROST FREE UNIT.
Without more detailed info on the unit, it would hard to say where your problem lies.
It could more than likley be a stat problem.
Make and Model numbers are always helpfull when requesting advise.
big tone the fridge man, February 2009