[Xringer]

Yeah Tom, that was my impression also.

I noticed the large plastic (screw-in) line-set caps on my first install didn't really seal down tight to the flare..
It's really just a dust cover. So, my line-set was likely pretty well loaded with moist air.
Right from the factory in China.

The Push-in plastic caps don't do much better at keeping down sea air infiltration.
Having the line-set sealed inside a plastic bag is a very good idea.

So, the vacuum operation is pretty dang important..


My point is:
When you unroll your brand new line-set, it would be okay to blow some dry air into into one end,
just make sure there wasn't any metal debris inside..

Any moisture left in the air inside the lines when you start your install,
should probably be flushed out a bit using your dry test gas (Nitrogen or Scuba air),
before tightening up the flares for the pressure testing. (Followed by vacuuming)..