AC accumulator / drier

I have a 2000 villager and it needs a new accumulator. I have done work on AC systems before but never replaced a drier. Do you know if I need to add more PAG oil to the system or just 134a? I have to assume the compressor still has all the oil it needs. The AC is still blowing cold and has freon in it still, which leads me to believe I caught this soon enough that the system is not contaminated. Once I evacuate the system, replace the accumulator and pull vacuum, what should I add first? Auto zone has a 134a can with a desiccant included. I'm glad the last time I refilled the system I used a freon with dye, otherwise I probably would have missed the mess yesterday.

Help.