The three usual causes on any freezer type: a failed compressor ($500 to $1,200 depending on model), a refrigerant leak requiring sealed system repair (variable cost, EPA 608 required), or a failed condenser fan motor allowing the compressor to overheat and cycle off ($180 to $350).
On chest freezers, secondary causes include a failed thermostat ($120 to $220 replacement, often the case with vintage chest freezers 15+ years old) or a failed door seal ($150 to $280).
On upright freezers, secondary causes are the same as refrigerator freezer compartments: failed evaporator fan, failed defrost system, or failed condenser.








