Digital thermostat mounted on a concrete wall

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Field pattern: evaporator ices up again after a defrost repair

A new heater fixes nothing if something else stops it from turning on or the melt water cannot leave. Techs trace repeat freeze-ups to the defrost thermostat or evaporator sensor, the timer or defrost control, a frozen drain or drain trough, heaters installed in the wrong position, or warm humid air from a bad door seal. The wrong turn is replacing the heater a second time.

Cross-checked ~60 min moderateBrands: All

Before you start

Unplug before removing the evaporator cover
Do not chip ice off the evaporator with sharp tools
Keep heat guns away from plastic liners

Diagnostic steps

Unlock all 6 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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