2004 Quest A/C

[questdaddy]

I replace my engine in my 04 Quest. But in between the motor swap was about 6 months of my A/C compressor just sitting there. i know that you are supposed to change the moisture evap thing. When i took to the shop to have it filled they told me that you can not change those on a Nisan, it has to be the compressor.

So my question is:
Can I charge my A/C system and have it work without any moisture issues.
Is the mechanic wrong? Do I really have to buy a $500 compressor?

Thanks for any info.

Quest Daddy