3791RD ice maker winter use question

[C&P RV]

We turn off the water under the sink, open the drain that's under the rv in the center (ours is blue), and let the water drain out. Since we don't live in ours, we drain the rest of the RV and then blow the lines out with an air compressor set to ~50 psi using an adapter at the fresh water connection. Then we put a container under the water dispenser inside the fridge and blow that out as well.
In your case if you are living in it, simply draining it will get the water out of the plastic PEX connections and you can turn it back on when the cold weather passes.