Switch works. Board works. There has to be something going on with that plug. You might consider a trip to radioshack or some such place to see if they have a replacement.

Thanks again for your help & patience....it'll be a couple of days before I can get back to trying to figure this out. Radio Shack doesn't carry the type plug & I've got a few days work out of town. Is it possible to get that 15ohm reading with a heater that doesn't work? The High Limit reset for this model is just a thermostat adjustment, but now I'm not getting any heat.

If it's reading 15 ohms it works, but it might not be getting power. Check the volts on the heater lines. If I can find a source for that plug I'll post it. Maybe we could also solicit additional comments from someone more familiar with this cool circulation system of yours.

After running overnight, I'm definitely not getting heat. I tested both wires from the heater and they both showed 120v. There's a third wire coming from the back of the heater that I haven't traced yet..not sure where it goes. It doesn't show up on the wiring diagram, but the heater was replaced a few years ago and I'm not sure if it's a stock heater.

You need to test both lines together to be sure you're getting 240v. You may have a relay that isn't closing, leaving you with only 120v which would show up on both terminals to ground.

Hi...I'm back in town. I jumped both heater wires at the terminal block and only got 115v, so it looks like I need to test the relays. It's not obvious from the wiring diagram on the panel which are the relays. Any direction on where to look and if they are likely to be soldered to the main board?
Thanks

Yes, it would be one of the soldered on relays.

Maybe I'm in over my head at this point....

I don't even do circuitry work myself. If you can determine which relay is not closing properly, then there's a chance you can find someone local to replace it for you. If you can't, you can either pay to have it sent off and tested or just purchase a new board. After shipping, labor, etc., some new boards end up being about the same price so see what yours runs before getting too far into it. If you need help finding the part/price let me know.

Hi,
My issue with the FLO2 error is that for the last 3 water changes, I have it after every water change. I have a Maxxus from 2004. Now that I am on my 3rd switch I decided to do some experimenting. Also - for background - I also just replaced my circulation pump because it went south . Anyways, as soon as I turn on the tub, I see the circ pump force the flow switch closed, and I get a FLO2 error. If I kink the hose behind the switch while the tub is turnes on, there is no error except for FLO. If I kink the hose and turn on the tub and then release the kink, all is fine - until the next filter cycle. Does this mean that there is some kind of circuit issue and the ciculation pump is triggering the flow switch too early??? Again, this is a brand new flow switch, and has only been installed in my tub since the last water change (2.5 months). This has happened twice before, and replaceing the switch fixes the issue until the next water change. HELP???