Which type of mobile a/c system will usually require additional time/precautions to extract all the refrigerant?

The Accumulator Type

It is commonly used in vehicles that do not have a thermal expansion valve, but rather, and orifice tube. Its main purpose is to control and monitor the amount of refrigerant coming into the air conditioning system. The accumulator can leak and when leaks occur, the refrigerant leaves the part as air enters the system. It can cause damage to the compression and this is one of the reasons why it requires additional time to extract all refrigerant from the A/C system.  

Sometimes, the accumulator type contains refrigerants which contain cheap hydrocarbon blends that are hazardous and highly flammable in the presence of an open flame or a spark within a confined space.  Desiccant of the A/C accumulator is sometimes full of moisture which in turn causes the orifice tube to block refrigerant flow and this also might usually require additional time to extract

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The awnser is d. i just looked it up