What should you do if you suspect that an alternative refrigerant had been used in the air condition system and it is not performing properly?

If you suspect that an alternative refrigerant has been used in your air conditioning system and it's not performing properly, first, cease operation to prevent potential damage. Next, contact a qualified HVAC technician to assess the system and identify the refrigerant type. They can safely recover the refrigerant, check for compatibility issues, and recommend the appropriate course of action, which may include recharging the system with the correct refrigerant.