If you have any verdigris on the chiller, it needs to be removed. For whatever reason, vinegar just don't work well on my chiller. If it has been too long between batches, I'll scrub it with a copper polish and rinse it a lot. Not letting hops dry on the coils is important.
As far as sanitizing, that isn't necessary. Just clean. You really don't want a bunch of copper oxide in your wort.
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