I have subject spa that has started clicking erratically when the set temp is reached. All indications are normal as far as I can tell. The power on light is lit, when spa water temp gets to set point ready light comes on. The heater light on the 2020 stays on, but I think that may be just the way it works. It stays on a little longer until the cycling starts. At that point the red htr light and clicking start cycling until I set temp up or down a few degrees and it responds accordingly, until the new set point is reached and it starts again. I've checked: flow thru circ pump, seems normal but I have no way to measure. I've pulled both thermistors out to see if there might be a blockage, nothing floated out. The pressure switch doesn't seem to be part of problem or I would expect system to shut down and it doesn't. My filters are clean. I ohmed temp thermistor and reading corresponded to table I found, around 6 ohms at 100 degrees and no fluctuation. My ozonator is out of system but lines are plugged off. I've giggled all the harnesses going to the 2020 to no avail. I've tapped the relays and the control head and no change. Voltage to spa is normal.
I changed the circ pump recently as the old one shorted out. New one shorted out after a week. Coincidental, I'm not sure, but I"ve checked everything I know how to for any sort of flow restriction and have found nothing. I have another one in now and it seems to be operating ok and not overheating however, I'm not leaving spa plugged in very long with this cycling problem. Spa has done this over the last few years but to a much lesser extent and it didn't repeat as much, so I didn't give it much thought until now. Is there any history with the control head causing this type of issue? Any help appreciated.