What must be done to ensure proper operation of heat and cool modes in an engine?

To ensure proper operation of both heat and cool modes in an engine, it is necessary for the engine to be running for a few minutes. This allows the engine to reach its normal operating temperature, which is essential for the heating and cooling systems to function efficiently. When the engine operates, it circulates coolant through the system, allowing both the heater core and the radiator to perform their intended functions. The heater needs the engine to be warm to provide adequate heat, while the cooling system needs to demonstrate its ability to manage temperature effectively.

In contrast, other options fail to facilitate this process effectively. Having the engine off does not allow for the circulation of coolant needed to assess and operate the temperature control modes. Checking in hot weather does not necessarily guarantee that both heating and cooling systems will operate correctly, as engine temperature management is more about the engine's state during operation than external temperature conditions. While full coolant levels are important for overall engine health and performance, simply ensuring coolant levels are full does not guarantee proper heating and cooling function without the engine being active to circulate that coolant.