Tiger River Spa Bengal Model M Hot Tub is Not Heating

[Evan P]

I'm hoping someone can help me solve a problem. In 2020, I purchased a home that had an approximately 15-17 year old Tiger River Spa Bengal Model M hot tub. It was working fine until February 2023 in the middle of our NJ winter and I noticed the water wasn't heating anymore. Since it was under freezing each night, I was obviously worried that the tub was going to begin freezing over. My local hot tub service company mentioned that they could replace parts but they had to get them first which might take some time. They were going to come and winterize my hot tub until the parts came in and repair it for a total of around $750. In any case, I turned off the breaker and unplugged the unit in order to try to reset the unit and it worked. The heater had been fine up until about 2 weeks ago.

I recently checked the hot tub and the water was cool. Since resetting the hot tub worked earlier this year, I decided I would try it again. The heater has not kicked back on and I am getting no heat to the tub water.

I took off the front panel to get to the circuit board and noticed that next to D15 there is a red light that says HTR ON. I assume this means the hot tub is calling for heat or maybe because it is red it isn't working? Other green lights are next to D13 LIM OK and D10. I think the D9 relates to the pump jets and seems to be working okay.

It has a brand new filter that is not clogged. All the pumps work fine. Could the heater be malfunctioning or some switch?

I'm not sure if anybody is able to tell what is wrong with whatever information I provided but any guidance would be greatly appreciated. Thank you.

[RDspaguy]

Most likely a bad relay on the small board. Test voltage to the heater.