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

For the heat and cool modes of an engine to operate properly, it is essential that the engine runs for a few minutes. This operation allows the engine to reach its normal operating temperature, which is necessary for the heating system to function effectively. When the engine is running, it circulates coolant through the engine block and the heating core, facilitating the transfer of heat. The heating core must be adequately warmed to provide effective heating to the cabin.

Additionally, running the engine helps to determine if the cooling system is functioning correctly, as it activates the air conditioning system and verifies that both heating and cooling outputs are operational. If the engine is off or has not run for a sufficient time, the systems may not operate correctly due to insufficient heat levels or poor circulation of coolant. This is why allowing the engine to run is critical for assessing the performance of both modes.