What can be done to prevent air from getting trapped in the cooling system when the coolant is replaced?

To prevent air from getting trapped in the cooling system when replacing coolant, ensure the vehicle is on a level surface and the engine is cool before starting. Use a vacuum fill tool, if available, to remove air effectively while filling the system. Additionally, fill the radiator slowly and keep the heater on to allow coolant to circulate through the heater core, helping to release trapped air. Finally, regularly check and top off the coolant level after the system has been run to ensure all air has been purged.