[CharlesYuhnke]

My display is flashing o l  then lo and it just keeps cycling over and over unit works fine and fluids are good .

I called the factory and they said it was probably a sensor. My aqua hot system, like yours, is working fine. Only the display it not working. I was told that there is a 3 wire system and a 1 wire system. If my memory serves me, the one wire system is newer. So when I take it over there, if I have the 1 wire; they'll just replace the sensor. If I have the 3 wire, then I think they'll have to replace both the sensor and display unit. Just haven't had time to take it over.