Alot of time, the compressor come filled with oil... if the hose ports are
sealed with rubber plugs. However, that is no guarantee. So what most
mechanic does is tilt the compressor so the oil will drain out and they
measure the amount of oil and compare it to spec.
I do not know what the spec for your car is... and oil is super super
important for compressor. There should be a green sticker by the radiator
that tells you how much oil you need.
You do need to replace your accumulator also as it may hold some oil too and
guarantee that your system is free of moisture.
Changing expansion valve is also highly recommended to make sure it doesn't
damage your new compressor.
Question... when you replaced the used compressor, did the compressor have
oil or was it empty? Most compressor needs at least 5 oz of oil.