We have a 2019 HM331RL. We have the Samsung residential refrigerator with the ice maker and I had our rig winterized this past Monday. I was told to empty the refrigerator and leave the frig doors and freezer drawer open at least 24 hours prior to winterizing. I had gone to our camper two weeks prior to winterizing and opened all the faucets and low-point drains after turning off the water. When we leave (it is on a rented site in a campground that is open March thru part of November) our camper after a weekend stay, we always turn off the water heater and the water. I went back about two weeks ago (we live in mid-state NC) and did all this because it was supposed to get really cold for several days or longer. I did leave the shore power connected and ran a ceramic tower heater with thermostat until I could get back this past Sunday afternoon.
Now to get back to the real story. The guy I had come to winterize disconnected the water line that runs along the outside of the slide that contains the entertainment system, stove/oven and refrigerator. This line goes to our refrigerator, He blue air thru the line to the ice maker to blow out any water. I had shut off the water supply to the ice maker earlier.
This is a new rig for us and a little different from our 2007 Keystone Cougar that I had winterized myself in the past. I wasn't quite sure about how to use this 'new" winterization system on our new coach so, I paid a local company to winterize and they will also come back and de-winterize in March 2020. Next year, I can do this on my own, but is still a two person job. Need someone inside to watch for the 'pink stuff' to come out of the faucets and someone to operate the pump on the outside pushing the antifreeze ('pink stuff') into the plumbing system. Don't forget to depressurize the water heater and remove the anode to drain the water heater and also by-pass the water heater.
Hope this diatribe was helpful.