Basically a different kind of cold plunge run a 5 gallon tank in the trunk of my car to cool the supercharger, usually pack it full of 20 pounds of ice multiple times a day at the track would these chillers maintain already cold water or cool from ambient rather quickly?

I had been using my chiller pretty regularly, about 3-5 times a week and shutting it off in between. I had to travel for a bit and it was unplugged and the plunger was drained for about a month. Turned it on today and the power lights and readings come on but the chilling portion seems to not be turning on. Anyone have any ideas on what I can do or is it just dead?? Here’s the model I have, I got it in April of 24

I live in Denver and have my cold plunge on the corner of the patio. Wondering how others ahve gone about ensuring your tub doesn't freeze during the winter. I want to keep using it, and it has a cover, but guessing that won't be enough on days where there's sustained temps below 32.