TL;DR
A defrost thermostat is the small bimetal safety switch clipped to a refrigerator's evaporator coil that allows the defrost heater to run only while the coil is below freezing, opening the circuit once everything warms to terminate the melt. Failed closed, it lets the heater overheat the compartment; failed open, the heater never energizes and ice gradually chokes the coil exactly as a burned-out heater would.
What it means
A defrost thermostat is the small bimetal safety switch clipped to a refrigerator's evaporator coil that allows the defrost heater to run only while the coil is below freezing, opening the circuit once everything warms to terminate the melt. Failed closed, it lets the heater overheat the compartment; failed open, the heater never energizes and ice gradually chokes the coil exactly as a burned-out heater would. Since the two parts produce identical symptoms and the thermostat costs a few dollars, techs test both and often replace them as a pair.
Where it sits in the glossary
Defrost thermostat is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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