TL;DR
A crankcase heater is a small electric element, a band around the compressor shell or an insert in the sump, that keeps the compressor oil warm during off cycles so liquid refrigerant cannot migrate into it. Without that warmth, refrigerant dissolves in the cold oil, and at startup the mixture flashes to vapor, foaming away lubrication and washing out bearings, a failure mode called a flooded start.
What it means
A crankcase heater is a small electric element, a band around the compressor shell or an insert in the sump, that keeps the compressor oil warm during off cycles so liquid refrigerant cannot migrate into it. Without that warmth, refrigerant dissolves in the cold oil, and at startup the mixture flashes to vapor, foaming away lubrication and washing out bearings, a failure mode called a flooded start. Heat pumps and air conditioners that sit through cold nights rely on it, which is one reason cutting power to the outdoor unit all winter is poor practice.
Where it sits in the glossary
Crankcase heater 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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