Hi, I have an older hot tub that I bought used. I'm pretty sure it was made by combining parts from several. I want to run in the "F3" mode instead of the "FC" mode to save power by not running the pump continuously all the time, however when I put it in "F3" mode after some time (longer than an hour, less than a day) it throws the "OH" code and stops running until I reset it. To be clear, when it is in the "FC" continuous mode, it does not throw the code.
So, my question is: Where do I start debugging? I've already replaced the limit switch recently for a different issue, so I don't think that's the issue. I can use a multimeter and solder if needed, but just wondering for likely culprits.
http://imgur.com/a/BULJE
Above are some pictures of the control panel.