Which would constitute the last step in a central-fan cooling control sequence? A) The blower continues to operate until the temperature within the fan unit rises above the setpoint of the internal controller, at which time the blower shuts off. B) Cool air from the fan system is delivered through ductwork to occupied spaces within the home. When the space temperature within the fan unit drops below the room temperature setpoint, the refrigeration unit shuts down. C) During the cooling season, when the home's air temperature rises above a predefined setpoint, the room thermostat calls for cooling and energizes the refrigeration control circuit. D) When the air temperature within the fan unit drops below the setpoint of an internal controller, the blower motor is energized.

The correct answer is: **A) The blower continues to operate until the temperature within the fan unit rises above the setpoint of the internal controller, at which time the blower shuts off.** **Explanation:** In a central-fan cooling control sequence, the typical steps are as follows: 1. **Thermostat Activation:** When the home's air temperature rises above the predefined setpoint, the thermostat calls for cooling and energizes the refrigeration control circuit (related to option C). 2. **Refrigeration System Activation:** This initiates the refrigeration process to cool the air. 3. **Blower Operation:** The blower motor is energized to circulate the cooled air through the ductwork to occupied spaces (related to option D). 4. **Monitoring and Shutoff:** The blower continues to operate, maintaining the desired temperature. The final step occurs when the temperature within the fan unit rises above the internal setpoint, signaling that sufficient cooling has been achieved. At this point, the blower shuts off to complete the cooling cycle (option A). Option A represents the termination of the cooling sequence, making it the last step in the process. **Answer:** A) The blower continues to operate until the temperature within the fan unit rises above the setpoint of the internal controller, at which time the blower shuts off.