What type of mobile ac system will usually require additional time and precautions to extract all the refrigerant?

A mobile AC system that typically requires additional time and precautions to extract all the refrigerant is one with a variable displacement compressor, commonly found in hybrid or electric vehicles. These systems often have unique refrigerant management protocols and may contain residual refrigerant in various components, necessitating careful handling to ensure complete extraction. Additionally, the presence of advanced electronic controls can complicate the recovery process, requiring specialized equipment and training.