So I looked at my manuals and I have the ClimateLineAir which is heated. Last night I put the climate control on manual instead of auto with the temp at 75F. Our room is 68F at night. I also slipped the tubing into the sash from a robe, then put it on the floor so any condensation would run back into the machine. I actually slept 5 hours with AHI at 0.8. But then the rainout woke me up again, and yes, you can see the water droplets throughout the tube.
My mask finally arrived today. I was prescribed the Amara View minimal contact full face mask, but they had the wrong size when I picked up my machine, so they had to order it and ship it to me. In the meantime, I had a nasal mask from a hospital stay a couple of years ago and have been using that for the last week.
Anyway, with the new mask, even the airflow feels different. With the nasal mask I had turned the minimum setting up to 7 to get rid of the not enough air feeling, but with the full face mask, it felt too strong. This mask also has an anti-aspiration valve that the nasal mask didn't have, so I'm thinking this may solve the rainout problem. So since this mask is so different, I'm going to reset everything to what it was when I brought it home and see how it goes.
I'm glad you talked to Resmed. It is a defect, no doubt. This explains why you and I are on our 4th machines and the problem persists. For people that need the humidity we have to find other ways to control the tube environment (hose covers, tube placement and run, room temp and humidity, etc....). Changing out A10s won't help as we now see. I can't remember what you said about your room temperature. Today's humidity in Dallas is 40%. Perhaps having some heat on in the room at night will help decrease room humidity. This helped me greatly.