RobBritinCali

Thankso. I agree- going to check on it in a minute to ensure it stopped heating at 104 degrees. Will test the HL sensor by dropping it in a boiling cup of water to see if it triggers a heating shut-down too. Thanks again

Thank you so much, ScubaDave! I found the HL sensor tucked behind the heater tube and released it. The sensor looks like new with no corrosion of any kind so I guess the unit has just failed and I can replace. The hot tub is currently heating up nicely to 102 degrees so I will be relaxing in it later watching this big Pacific storm blow through the Sierra Nevada mountains. Many thanks again!

HI, I have an older Sundance Spa. Recently I replaced the filter, the pressure sensor (precautionary) and the circ pump as it had failed. The spa now works almost perfectly except the HL warning keeps tripping at 93 degrees. If I re-set the GFI I can normally make it run for a few more minutes and get to 94 or 95 degrees and, if I'm lucky, I can keep repeating that and get it to 100 or 101 before it cools back to 93. Any ideas what could be the cause? I've attached photos of the unit. I know the HL sensor is the second red connector on the top right but not where the thermostat is or if there is a "heat well" to check? Is it possible there is a blockage after the heater that is causing to water flow to slow and peak in the heater element (if that's where the temp sensor is)? Thanks Rob

Thanks for your response. The filter is new and I checked the flow lines through from that, though the heater and into the spa and there are no blockages so I've eliminated that as the issue. I couldn't see any mechanical timer on the board either and the circuit diagram (attached) doesn't appear to snow the presence of one either. As for the pump- it wasn't rusty but the back of the impellor and around the shaft had lots of mineral deposits on them (possibly Chlorine etc) which game me the impression it had leaked possibly. I couldn't see any other signs of damage on it though Thanks spa circ dia_1.pdf

I have an older Sundance spa that came with my vacation home. When visiting this weekend, I found an "FL O" error on the tub and it would not heat. (All other functions, blowers, lights etc work). I took out the circulation pump, it appeared to be stuck and then it freed up. I refitted it but it still did not run. I also tested the pressure sensor and tripped it into closing which started the heat but still no water flow (Stopped that after 5 seconds to avoid any burn-out/over heating etc). I'm pretty certain the circulation pump needs replacing, but I want to check it first but am not sure if it constantly runs or not - If it does then I know I should expect a constant voltage to it whilst the spa is on. Thus, my question is: Should the circulation pump be constantly running even when the spa is not heating? Any advice would be great, thanks