Lifesmart LS 450DX keeps heating and will not shutoff

[CameronC]

I have a Lifesmart LS450DX hot tub that worked great for about 4 years. Then I started having a problem with the tub heating and not shutting off when it should. I've seen several threads about this but no real solution. I have followed the recommendations of adjusting the filter cyle (even with it set not to cycle the problem continues) and cleaning the filter more frequently. I have replaced the control box, the temperature sensor, and the top control panel. Each time a part is replaced the problem will go away for a bit and then start returning with increasing frequency. The control panel shows it is reading the correct temperature, but it doesn't shut off at the specified temperature. Ultimately the high limit (HL) will trip and the tub will shut down. The temperature reading is correct (checked with thermometer) and the HL safety feature functions as it should. I wanted to see if anyone had a permanent solution that took care of the problem. This is a 110V tub with no separate heater, so there are really a limited number of components that could be malfunctioning.

[RDspaguy]

Post pics of equipment area and circuit board.

[CameronC]

On 1/8/2024 at 11:18 AM, RDspaguy said:

Post pics of equipment area and circuit board.

Thanks for the help!

[RDspaguy]

Ok. The mystery is that it corrects for a while then returns. 

The temp sensor is accurate and it shows the tub gradually overheating as it continues to run the pump, or it shows a normal temp then triggers an overheat error randomly?

I'm not familiar with that system, @CanadianSpaTech is the local gecko expert. Maybe he has some insight.