Liebherr · Refrigerator error code

BT021Refrigerator evaporator (newer controls) sensor fault

Cross-checked Power off, standard tools

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Related diagnostic guides

Guide · Refrigerator

Premium built-in refrigerator: one section warm (Sub-Zero vs. Monogram logic)

Start by knowing the architecture. Sub-Zero built-ins have two separate sealed systems, so a warm section means a fault in that section's own fan, defrost, sensor or system. Monogram built-ins share one freezer evaporator and feed fresh food through a damper, so a warm fresh-food side with a cold freezer points at the damper, airflow or an iced return passage.

6 steps ~60 minmoderate

Guide · Refrigerator

Refrigerator runs all the time

First decide if it's really a problem. Whirlpool says 40-80% run time is normal at average room temperature, and newer variable-speed compressors are designed to run long at low speed. If it's truly excessive, the usual causes are heat-rejection problems (dirty condenser, dead condenser fan), air leaks (gaskets, doors) and a frosted evaporator. A compressor or refrigerant fault is a referral.

8 steps ~45 mineasy

Guide · Refrigerator

Known issue: Whirlpool / Maytag / KitchenAid three-door French-door 'frost clog' (fresh food warm, freezer OK)

A class settlement (Paperno v. Whirlpool, N.D. Cal., final approval May 13, 2025) covered certain Whirlpool, Maytag and KitchenAid three-door French-door refrigerators built roughly 2012 to 2019 that may not fully defrost the fresh-food evaporator, so frost and ice block airflow and the fresh-food section stops cooling. Whirlpool denied wrongdoing. The settlement reimbursed documented evaporator repair or replacement costs within limits; reported claim deadlines were in 2025, so new claims are likely closed. The repeat-icing pattern is still common in the field.

8 steps ~90 minadvanced