Heat PumpTroubleshooting2026-01-30
Understanding the Heat Pump Defrost Cycle
Steam and a brief pause in heating are normal defrost behaviour — not a fault.
Many homeowners worry when their heat pump pauses and steams in winter. That's usually the normal defrost cycle doing its job.
What defrost does
In cold, damp weather, frost forms on the outdoor coil. The heat pump periodically reverses to melt it, briefly pausing heating and producing visible steam — entirely normal.
When it's a problem
If the unit defrosts far too often, never clears the ice, or stops heating afterward, the defrost sensor, control board, or refrigerant charge may be at fault.
Key takeaways
- Steam during defrost is normal
- Brief heating pauses are expected in winter
- Constant defrosting signals a fault
- Don't block the outdoor unit
Need help with your heat pump?
Licensed, gas-certified technicians serving Greater Vancouver since 1999. CombiBoiler.ca — A division of ROMA Heating Ltd..
Frequently asked questions
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