HVAC ANSWERS · EQUIPMENT AND EFFICIENCY
Heat-pump defrost cycles
Canonical HVACentric knowledge for residential questions on this topic.
DIRECT ANSWER
Some frost on an outdoor heat-pump coil can occur during cold-weather operation, and the system may temporarily reverse operation to defrost it. Water vapor during that cycle can look like steam. Thick ice that remains, repeated ineffective defrosting, unusual noise, or loss of heat should be evaluated because airflow, drainage, controls, sensors, or equipment operation may be involved.
Questions this topic covers
These are examples of natural wording that map to this maintained topic. They are not separate pages or duplicate answers.
- Why does my heat pump go into defrost mode?
- Is steam from the outdoor heat pump normal?
- How long should a heat-pump defrost cycle last?
- Why does the outdoor coil frost in winter?
- When is heat-pump ice a service problem?
Sources used for this answer
HVACentric uses public primary and authoritative sources as research anchors. Property-specific decisions still require direct verification.