Improper refrigerant charge can result from various factors, including installation errors, leaks, system component failures, and inadequate maintenance. Other causes include incorrect system sizing, poor design, and changes in operating conditions. For example, if the system is not properly evacuated during installation, air and moisture can enter the system, leading to improper refrigerant charge. Similarly, leaks in the system can cause refrigerant to escape, resulting in undercharging. Regular inspections and maintenance are crucial to identifying and addressing these issues.