Sundance 680 series Fl1 and Fl2 errors

dan1333 · Sep 9, 2022

Hi, I have a Sundance 680 series hot tub which is about 2 years old. Haven't had any issues except about a week ago on an excessively hot day (it had been over 100 outside for about a week) I suddenly got a Fl2 error code. Pump 1 still worked at low and high speeds and pump 2 still worked. There's no circulation pump.

I don't know if the heater was working because I had it set to 90 and the water was already 105 just from the cover being on it and the hot weather. Basically, it seemed like everything was working except for the Fl2 code on the display.

After about a day I checked again and this code was gone and stayed gone for a week.

Today, I went out and saw now an Fl1 "flow error open" code. Again, the 2 pumps work normally and the water was 95 just because of the hot weather and the cover on it. So I don't know if the heater is working or not.

Anyone have any idea why I got that Fl1 error code that disappeared and now an Fl2 code? I took out the filter and blasted it with the hose like I normally do every few weeks and it was empty and clean as usual. The water level has been fine.

Is the flow sensor just bad and needs to be replaced? Not sure what the next step should be.

Thanks in advance

ajw22 · Sep 15, 2022

Maybe @RDspaguy has ideas.

RDspaguy · Sep 17, 2022

The flow switch is a common issue, and what you describe could be the first sign that it's going. You can test the switch with an ohm meter, though intermittent errors can be tricky to catch. Or you can put in a new one and see.
Check the harness (at the board) for loose wires or corrosion, and the wires for rodent damage.

dan1333 · Sep 17, 2022

Yeah today I spontaneously get no errors and everything is working as it should. I'll open it up and check for loose wires and any damage. Thank you!!

dan1333 · Oct 3, 2022

Just an update if anyone wonders what the issue was. As RDspaguy suggested, I opened it up and checked the connections and wires. Seemed like the connection to the main board was loose so I plugged it all the way back in. It's been a week or so and no errors and everything is working properly.

Just in case I bought a new flow switch but I'll keep that for the future and replace if the issue pops up again.

Thank you!

dan1333 · Oct 28, 2022

Well unfortunately the flow error kept popping up randomly so i just replaced the flow switch. After I powered it back up I'm still getting a fl-1 flow open error on the screen.

Anyone have any ideas now? Is the main board bad already? The whole tub is 2 yrs old.

Thanks again

RDspaguy · Oct 31, 2022

Did you replace just the threaded switch, or the housing too? If you screw it in too far or have it slightly off-center in flow direction it won't work.
The fact that messing with the harness fixed it for a while suggests it is a problem. Those little ends won't clip in if installed wrong or if the harness is damaged and can push out instead of onto the pin. Corrosion, moisture, cobwebs, you name it can short out harness terminals. I have seen several instances where removing the board and toothbrushing both sides has fixed control issues. You never know, but I'd check EVERYTHING twice before buying one of those $$$$ boards.