Final answer:
The heater/resistor in the thermostat control circuit for a device that can heat and cool is active when the thermostat detects the space is above the desired temperature in cooling mode.
Step-by-step explanation:
The heater/resistor in the thermostat control circuit in the cooling mode is active when the thermostat senses that the temperature of the space is higher than the desired temperature set on the thermostat. In the context of a device that can both to heat and cool a space, during the cooling mode, the heater or resistor may be used to regulate the temperature or for other control circuit operations. In heating mode, the basic components include the working fluid, which absorbs heat from the outside air in the outdoor coils, or evaporator. This is similar to how a heat pump or refrigerator operates, but the focus here is on the heating aspect rather than cooling.