Final answer:
During the defrost cycle, the system switches to the Heating mode. Heat pumps can operate in reverse to provide heating instead of cooling.
Step-by-step explanation:
During the defrost cycle, the system switches to the Heating mode. Heat pumps, such as air conditioners and refrigerators, can operate in reverse to provide heating instead of cooling. In the defrost cycle, the heat pump extracts heat from the environment and transfers it indoors to warm the living space.