Hi, any help is much appreciated.
I have a 2010 Sundance 780 Series Hamilton spa that we inherited when we bought our house. It stopped working about a month ago and I've been troubleshooting it off and on and feel stumped. The issue started with the GFI being tripped. When I reset it, things appeared normal and then I started getting the "---" watchdog error. Everything I read online said this is usually a bad sensor. I replaced temp and high limit sensors and still got the watchdog error. Then the GFI started tripping again and I realized the heater was leaking a bit and badly corroded. So I just replaced the heater assuming that the corroded contacts were throwing funky voltages that set the board into watchdog mode. I'm still getting the watchdog error. It seemed random at first, but the more I've been troubleshooting I feel very confident (but not 100% sure b/c I've never actually been able to see the exact moment it goes to watchdog error) that the error is being thrown at the END of a heating cycle. The tub will heat as long as necessary depending on the starting temp and then error once it's done. So if the water is 95º and it's heating to 100º, it will heat fine for maybe 1-1.5 hours, all jets work, etc. until it gets to 100º and cycles off and then I get stuck in watchdog mode. OR if the water starts very cold like it just did when I refilled it thinking the heater issue would fix everything, it ran fine for several hours (7+ hours) heating the water from 51º all the way to 100º and only THEN did it throw the error. So it seems really closely associated with cycling the heater off.
Does this suggest any other components for me to inspect/replace outside of the temp sensor, high limit sensor, and heater? Should I look at the 240 volt transformer? Or does the consistent error point (end of heating cycle) suggest I need a whole new board?
Thanks!