When using the 4-way valve in Winterize position, the antifreeze will be sucked in the main water inlet, through the short connecting hose, and through the 4-way valve's cartridge on its way to the water pump.
The areas that antifreeze don't go through are 1) the black tank flush since it's separate, 2) the water line from 4-way valve to fresh tank, and 3) a short area of water line from the 4 way valve going to the water fixtures, before reaching the tee coming from the water pump output. I don't think we've seen any posts about freeze problems in these areas, although I've wondered if black tank flush anti-siphon valve problems stem from freezing.
To be certain water is evacuated from these 3 areas, you could start the process using compressed air, rotating the Anderson Valve through the CITY and TANK positions, and then set it to WINTERIZE to suck in antifreeze. And of course compressed air will clear the black tank flush line.
You'll also want to pay attention to the water feed line for your refrigerator, along with chill coil and filter if you have a residential refrigerator. Check out the
Residential Refrigerator Guide for help with that.
And don't overlook the washer prep, even if you don't have a washing machine. More detail is available in the
Winterization Guide.