Always be consistent when charging a system. Following best practices each and every time can prevent cooling discrepancies and/or failed system components.
 

• Initial charge is liquid on the high side of the system.
• topping off charge is vapor on the low side of the system.
• remove blended refrigerants from the cylinder as a liquid.
• use charging charts and graphs and weigh in the charge.
• verify good airflow across the evaporator.
• verify superheat and subcooling.