Mixing different refrigerants in an HVAC system can have severe consequences, including system failure, reduced performance, and even safety risks. Different refrigerants have unique chemical compositions, and mixing them can lead to adverse reactions, such as acid formation, corrosion, and explosions. This can result in costly repairs, system downtime, and potential harm to people and the environment. It is essential to always use the correct refrigerant type and follow the manufacturer’s guidelines for refrigerant handling and charging.