I have a hotsprings sovereign w/ a trumpet style heater that inconveniently has a switch on the unit itself. ( is this a high limit?) It occasionally trips much to my chagrin.
I have assumed it was a circ. problem similar to what I had on a former tub which was simply hair in the intake. The location was a bad spot on that model.
My assumption has been that the heat switch trips when the filters clog. Why you ask, well the intake is through them on this model, which seems a good design, and there is a telltale sign. Less bubbles from the ozonator, or rather the injector. This is how I knew I had to put my finger in the other models intake ang scrape the lint and hair out off the screen with my finger nail- Guacala! So my assumption is similar for this one even though its got three freaking filers. It is obvious the center one does most of the pulling (ps there is a silver cartridge in it) because it is dirtiest. The switch seems to trip out on or after cleanup cycle whick kinda makes sense also.
Anyhowz maybe I'm wrong. Just pulled the filters and they dont look bad this go around. Other possibilities? Crustified heater innards?
I have a NIB no fault pdr heater as back up.

filters need to be CHEMICALLY cleaned every few weeks. 3-4 weeks. Not just looked at or hosed off. You can't see what is clogging them. You can, if time is limited, swap that filter with one of the others. That may get you another week.
If you're cleaning the filters as you should and still experiencing a problem, look at the floating skimmer weir. When you turn on the jets, does it stay in the up position? Does it not float up and down as it should? Is your water level low?
Plenty of hotspring help here....

Well I bet thats it. I do occasionally chem clean it, but this last time I just rinsed it. I did have the Hawaiian Tropic girls rinse off prior to tubbing the other day, but there does seem to be an oily coconut residue. I will be more diligent with chem cleaning. I have a lot of the spray for that purpose.

On the weir, that has never seemed to float up well.

a sticking weir can present the problem where the filter compartment temporarily empties partially when the jet pump is turned on. Remedy that by replacing the weir and quidebody, or removing the weir itself, or just push it down, so it stays down.

So then Air goes down the intake and the heater overheats and the switch trips?

I'll pin it down.

yes.

The chemical clean did the trick. It was the hotsprings stuff. I clearly have better flow, I have much more bubbles comming out into the tub from the ozonator/injector, which I have posted elsewhere can be a telltale sign of how your circulation is doing.
what the heck is that stuff, it had a familiar odor to be sure and was probably the sudsiest stuff ever. hope it doesnt kill the plants around where I rinsed it. Took a very long time to get it fully rinsed. Looked about like the first, and last time I put too much detergent into the washing machine.