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Sounds like it could be the heater relay or the temp sensor in the tub itself.
Understood, thanks. Wonder why he couldn't find anything wrong last time. Will try again -- feel free to let me know if anyone has any further insight in the interim.
Free Visit/discount...WHY? If the spas was working as it should while he was there how do you fix a problem that isn't there? Not his fault. You can test everything and not find an issue. He spent his time testing, driving to and from. If the problem isn't present and you can't replicate the issue while he is there that's not his fault. Call him when the issue is present so he has a chance to diagnose the problem. JMO
I do as well most of the time... my point is that it should not be expected or the tech be blamed for not finding issue when the spa is running perfectly while he was there.