Hot Spot Soft Side Round - Temperature Control Problem:

Some History: I have a 1994 Hot Spot sn Z240751 - Last year, around the summer, the unit was having issues with the Temperature Control. It would start to go up as high as 110 before the High Limit would kick in. I took it apart and found a relay was faulty, along with a couple of fried wires.
I replaced the relay and repaired the wires. It was working fine for about 6months then began to repeat the High Temp issue, but not as often. I rarely use the tub in the Summer, so I turned the thermostat from 7 ( 102F) to 5 (95F). I didn't hear the unit circulating too often. I checked it a few times and it was that the temperature was OK. I looked at it last week (getting cooler out now) and the High Limit kicked in. The thermostat was still at 5 and temperature was at 104F. I reset the High Limit switch once the temp dropped.

Now, getting to clean unit and prepare it for the fall/winter, I have taken on the task of removing the Control Unit and troubleshooting once again. I have found that the relay is still OK, and no wires are fried. I thought of just replacing the Thermostat and trying that out first. I talked to a Dealer in OHIO, who sold me the replacement parts last year, and he said that my unit was the first one he has seen any problems with. Hmmmmmmmm???

Any suggestions as to why this keeps happening, and preventions?

Thanks Guys

He's never seen that problem in that spa...Hmmm. Interesting comment from a dealer.

That problem is not too unusual.

I would replace the thermostat. I guess you know in that year you have to drain the spa to do it.

The other thing would be a stuck relay, but the spa would be constantly running in low speed. (This could also happen with a bad t-stat). You test the relay by removing the wires to the relay at the 4 terminal end and testing continuity across the inner and outer terminals. If you get continuity the relay is stuck.

Those are my two best guesses. Let us know how it comes out.

Thanks for your quick response, and your suggestions.
I think I will replace the Thermostat and try that out.

Doing some deck staining first, so I'll post an update soon.

Thanks again.