I have an older model Northwest Spa.
The model is a 620D 240V. They use Balboa Instruments for the internal components.
The tub has been working fine for several years. Now when I turn the tub on it will run for 1 to 2 hours but then shuts off with an "OH" reading? If i press the temp button it will start again and run for another hour, but then shuts off with the "OH" reading.
Any idea's on what the problem is?