Final answer:
During the defrost cycle of a heat pump, the correct sequence includes the compressor operating, the reversing valve being activated to change refrigerant flow, the outdoor fan deactivating to aid coil warming, and the auxiliary heat engagement to supply indoor heating. Option C is correct.
Step-by-step explanation:
The correct sequence of events that happen during the defrost cycle of a heat pump is option (c): Compressor operation, reversing valve activation, fan deactivation, auxiliary heat engagement. Here's how these steps work in the defrost cycle:
Compressor operation: The compressor continues to operate to provide the necessary pressure increase for the refrigerant.
Reversing valve activation: The reversing valve is activated to change the flow of refrigerant, effectively turning the heat pump into an air conditioner temporarily to melt any ice that has formed.
Fan deactivation: The outdoor fan is turned off to prevent cold air from moving over the coils and to increase the temperature of the coils faster.
Auxiliary heat engagement: The auxiliary heating elements may be turned on to provide temporary heat to the indoor space during the defrost cycle since the heat pump is not heating during this process.