TL;DR
The defrost cycle is a heat pump's periodic self-thawing routine: the reversing valve briefly flips the system into cooling mode so hot refrigerant melts frost off the outdoor coil, while the outdoor fan stops and auxiliary heat tempers the indoor air. A cloud of steam rising from the unit and a whooshing sound every 30 to 90 minutes of cold, damp weather is the system working as designed, not failing.
What it means
The defrost cycle is a heat pump's periodic self-thawing routine: the reversing valve briefly flips the system into cooling mode so hot refrigerant melts frost off the outdoor coil, while the outdoor fan stops and auxiliary heat tempers the indoor air. A cloud of steam rising from the unit and a whooshing sound every 30 to 90 minutes of cold, damp weather is the system working as designed, not failing. What does warrant a service call is a coil that stays caked in ice, a sign of a stuck reversing valve, bad defrost board, or failed sensor.
Where it sits in the glossary
Defrost cycle 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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