DIAGNOSIS Excessive frost means warm, humid air is getting in. The cause is either a door left open too often, a bad seal, or the door not closing fully due to an obstruction.
FIX First, defrost completely. Unplug, empty, leave door open, and place towels. Once melted and dry, check the door seal (gasket) for tears or debris. Clean it. Ensure nothing inside (like a food package) is blocking the door from shutting flush.
IF THAT DIDN'T WORK The fridge might be over-packed. Air needs to circulate around items. Leave some space, especially near the cold air vent at the back of the freezer compartment.
HEADS UP These are manual defrost units. You need to do this every few months if frost builds up more than 1/4 inch. Never use sharp objects to chip ice—you'll puncture the interior liner.