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Walk-in freezers · Diagnostics · 6 min read

Commercial freezer won't defrost: diagnostic path

Ice buildup on the coil means the defrost cycle isn't completing. Here is the sequence techs use.

Section 01

Confirm defrost is actually running

Force a manual defrost via the control. Listen for heater energization.

Section 02

Test defrost heaters individually

With a clamp meter. A failed heater reads zero current; all heaters should energize together.

Section 03

Check defrost termination

Thermostat or klixon sensor. A stuck closed contact ends defrost prematurely.

Section 04

Verify drain line is open

If water from defrost can't drain, it refreezes on the coil and compounds the issue.

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