Why is my 1997 Hot Springs Sovereign hot tub not heating?
Not sure if this helps but I ran in to something similar. If your tub gets too hot, it might go past its heat limit and stop heating all together. There should be a high limit reset switch that you'll need to hit to get it heating again. Just adjust the temperature setting so it doesn't hit the limit. Mine was showing that it was heating on the top panel, but wouldn't start heating until I reset the limit switch. I had prior work done to it and the tech cranked the heat all the way up to test something and I overlooked it once we got it going again.