flo control problem

Hello, I have an Altimar 850 hot tub. I am having an issue with the flo appearing on the panel screen. I have checked the filter and removed it and the flo still shows up. I have checked the circulating pump and everything appears good. I have removed the wires from the flow control valve and jumped them together. The problem goes away for a short time and then flo returns. Unhook the wires from the jumped wires and problem is good for an hour or so. I have checked for an air lock. Not sure what to check next. I have removed and inspected the flow control valve.


  1. Reply

    Glenn is the FLO msg flashing FLO ie Flashing FLO and then the temperature of the water or is the FLO msg SOLID with no water movement and your control panel locked out?

  2. Glenn Asselstine


    Thanks for the quick response The flo is solid and control panelis locked. I un hook the jumper wires and evverything goes back to some what normaal for a short period of time.

    Thank You

  3. Reply

    Glenn, Remove your sensor harness connector on the PWA.  Tug on the Flow switch wires.  If they are loose or come away from the harness, resecure them.  If the wires are tight remove the two flow switch wires from the harness and re-install the harness on the PWA.  Turn power back on to the spa.  Does the spa reactivate and flash FLO?  If so you may have a bad PWA.  If the control panel does not flash FLO turn power off to the spa and remove the flow switch wires again.  Visually inspect switch for debris.  If no debris is present test across the two wires with your multimeter in the ohms position.  Test switch for continuity when closed and for infinite when open.  If you don’t have these readings you likely have a bad Flow switch.  If you do have these readings check that the flow switch arrow points in the direction of flow and adjust and retest the system if not.  If all else fails contact our Service Support Desk to perform a diagnostic and repair of your Sundance Altamar spa.

  4. Glenn Asselstine


    I did everything you had mentioned and tub seemed okay for a few minutes no flo has disappeared and now it show P1 u9 flashing I have looked in the manual and the internet and can’t find what that code means. I have turned power off and restarted everything but it has come back twice now.

  5. Reply

    Glenn what did your multimeter readings show when you tested the leads on your Flow switch?

  6. Glenn Asselstine


    I didn’t do that step as everything appeared good. the control panel didn’t show flow just the temperature. Then 5 minutes later it showed P1 u9 I looked in manual and no error code for this.

  7. Reply

    Glenn if the sensor harness is loose or not connected long enough you can get a msg on the
    control panel that says “plug”. The flow switch requires testing to determine if
    It is good or bad. If all else fails contact our Service Support Desk to book a
    diagnostic and repair of your Sundance Spa.

  8. Glenn Asselstine


    I double checked the sensor harness and one wire might have been a little loose. Refastened and check the flow control switch and had a fluctuating reading between 1.3 – 1.5 what does that tell me. the heater was activated as the temp was about 5 degrees below where it was set.

  9. Reply

    Glenn when doing an ohms check you should have continuity when the switch is closed
    and an infinite reading on your multimeter when the switch is open. If you have these readings
    your switch should be good. If you don’t have these readings your switch may
    be bad. If all else fails contact our Service Support Desk to book
    a diagnostic and repair of your Sundance Spa.

  10. Glenn Asselstine


    sorry what do you meaan continuity. Infinite reading means what. Tub is heating up so flow must be open and ohm shows 1.3 – 1.5

  11. Reply

    Glenn, continuity and infinite are terms used when doing and ohms check on a NO/NC switch. If the heat icon is on check for 22amps around one of the heater wires with your amp probe on your multimeter. 22amps is proof the heater is heating. If the heater icon is on and the heater is heating you should not have a FLO msg and the switch should be in the closed position and you should have continuity at the leads. If you do not you could have a bad Flow switch. If all else fails contact our Service Support Desk to book a diagnostic and repair of your Sundance Spa.

  12. Glenn Asselstine


    I have checked the heater and it shows 23 amps. The temp is set at 39 this morning it was 35 and showing flow unhook the lead on flow switch and tub works, heats up to its desired temp. As soon as it hits 39 it will then show flo. It will also maintain heat for a while but no functions will work until I hook or unhook the flow control wires.

  13. Glenn Asselstine


    I started up my 1999 Altamar 850 a month back and had some minor issues. No problem all fixed except the flo appearing again. Filter is fine, circulation pump is working, and installed a new flow control switch that I purchased from Aqua tech. Tub set to 39 degrees tub is heating everything working well, reaches temperature and click a solid FLO jumped some wires from the board to flow control and un hook wires FLO goes away but temperature will drop. Attach wires heat performs to desired temp and click FLO appears. Stopped by your shop the other day and almost fell over at the cost of a service call. We have been back and forth on this issue since last year. I just cleared all error codes – nothing overly concerning. What else can it be? very frustrated hot tub owner.

    • Aqua-tech Support


      Glenn is the FLO msg solid as in it is locked in the panel and no other functions work when the msg is there ie pumps etc or is the FLO msg flashing ie FLO, temperature reading FLO and the pump functions still work?

  14. john


    solid flo temp 114 all pumps running,did continuity on flo switch checked ok

    • Nigel


      John, what make and model spa do you have? What was the year built of your spa? All of this info can be found on the serial number label located near the Sentry Control Box.

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