Jacuzzi Z110/310. The heat is always on until the high temp sensor kicks it off. I tested the resistance and both high/low seem to be close (non-digital multitester). Every thing else works. I am trying to decide if it is the controller or the sensors.
H490000 model.

Any thoughts?

Never mind. I ordered both replacements.
Turns out the H193000 unit (control unit) was bad. All is working once again.