Doctorhawaii

Okay, this is what I was looking for…thanks! It does have a pressure switch, and it going bad makes the most sense as the culprit. Also: The thermistors test properly. The circ pump operates properly. The filters are new and clean. So, if I remove the pressure switch connector, cut the wire and make a jumper and reconnect that, is it safe to run the tub? If the thermistors are working properly doesn’t that prevent overheating in the absence of the pressure/flow switch? Thanks!

Anyone have any other thoughts to try and figure this out? Please???

So I powered the tub down and checked both thermistors, and they read properly (6.55/6.60 K Ohms at 97 deg.) I powered it back up and everything is working normally, as usual. The circ pump is quiet and cool and seems to be fine, and there's no change in the flow when I remove the circ filter (which I recleaned.) Any other ideas? The pressure switch itself? Thanks for any thoughts...

Well, I answered my own question. Same thing happened again, the tub shut down after running fine for a week, and the red power light is blinking, despite clearing/cleaning the Venturi tube. I’ll check the thermistors tomorrow…

Hey there RD. Thanks for your thoughts. The tub temp is spot on. On the circ pump, I replaced the original a few years ago and, on checking it, it runs quietly and there’s as strong a flow from the waterfall as ever. But this is interesting (and in line with your idea): I noticed the ozone bubbles were way less than usual and a couple of days ago they stopped altogether. So I pulled off the ozone tube from the injector/Venturi and it was completely clogged with calcified buildup. After removing all of that, the suction was strong and the bubbles are great. I still have the original heater with the pressure switch, and since I normally (but not always) shut the waterfall off after I use the tub, I wonder if that clogged ozone injector reduced the circ flow enough to trip the pressure switch? That would explain the intermittent/random shutdown. What do you think?

Looking for suggestions: I'm in Northern California, and I have a 2005 Vanguard that has worked flawlessly all these years--I take very good care of it. However, for the past 6 months, the high temp limit trips and I get the flashing red power light. Sometimes it happens once a month and sometimes a couple of times a week. When I shut the power off for 30 seconds and reset it, everything works fine for several days to weeks, until it trips again. The filters are fresh and clean, the circ pump is good and the circ flow is strong. Both the main and aux control panels work great. It seems to me that if the heater element is failing or scaled, it would trip rather quickly after resetting, and it seems like that would be the case for the high limit sensor too. So I'm stumped as to what to try, and I'd rather not have to spring for a new heater if I don't need it. Any suggestions or ideas would be much appreciated.