Why is there a big block of ice in my fridge?

A large block of ice forming inside a refrigerator section usually indicates a blocked or frozen defrost drain line. When the automatic defrost cycle melts frost off the coils, the resulting water is supposed to flow down a drain tube into a pan beneath the fridge. If food debris, mold, or algae clog this drain tube, the water backs up, pools at the bottom of the compartment, and freezes into a solid block of ice whenever the refrigeration cycle turns back on. Flushing the drain tube with warm water and vinegar clears the blockage.

Finding a large, solid block of ice inside your refrigerator or freezer compartment is typically caused by a severely clogged defrost drain hole, a stuck door left ajar, or a failing automatic defrost mechanism. When the defrost drain tube gets plugged with food particles, dust, or ice, the melted frost from automatic defrost cycles cannot escape down into the drain pan beneath the appliance. Instead, the trapped water pools on the floor of the compartment and refreezes into a massive solid block during the next cooling cycle. Alternatively, a torn rubber door gasket allows humid room air to rush inside, condensing and freezing rapidly upon contact with cold surfaces. To fix this, you must manually melt the ice block, clear out the drain tube using warm water and a flexible brush, and check door seal integrity. You can verify success by ensuring water flows freely down the drain hole and no new puddles form.