http://www.rpod-owners.com/forum_posts.asp?TID=14122&KW=&title=rpod-survives-9-hours-of-subfreezing-temperatures
As a follow-up to that experience, we returned from warmer climes to the Denver suburbs on the Sunday after Thanksgiving this year in the unwinterized R-Pod, arriving after dark. Temps at the house were predicted to bottom out at maybe 26 degrees F for maybe 6 hours. Well, once again we must have been lucky as they sank to the high teens for most of the night. I did run a space heater in the Pod overnight.
At about 10AM I hooked up the compressor and attempted the blowout. Outside shower/goat washer blew out fine, but air would not move through any of the inside lines

I tried a couple more times. No luck. At about 2 PM, with temps in the 60s and the R-Pod in direct sun the lines finally opened up and all blew out as normal.
I don't think anything broke, but when we next hook up to city water we'll see just how big a dumba$$ I was...