During defrost cycles in heat pump operation, which component is energized to aid heating?

• A. Progressive fan speed control
• B. Defrost timer
• C. Strip heaters
• D. Compressor off switch

Answer: (C)

Electric strip heaters provide supplemental heat during defrost. When a heat pump goes into defrost, the outdoor coil is heated by reversing the refrigerant flow, which reduces the heat available to warm the indoor space. The electric strip heaters in the indoor air handler are energized to add heat to the airflow, helping maintain comfortable indoor temperatures while frost is being melted on the outdoor coil. The other components don’t supply heat: fan speed control only adjusts airflow, the defrost timer manages defrost cycles, and the compressor off switch simply stops the compressor.