Most likely you have 1 of 2 problems.
- Your flow meter is not sending a signal to the controller or the signal is being blocked for some reason. A bad wire or wire connection from the flow meter to the controller. The controller knows you are not reaching your application rate (it says zero), so the control valve continues to open more and more until it is all the way open. The control valve is opening in an attempt to reach your programmed application rate.
- The other most likely reason is that there is a programming error in your rate controller. If you enter an incorrect speed calibration, flow calibration, or width calibration. For example, if you entered 4500 in as your applicator width when it was supposed to be 450 (easy common error). The controller would think the applicator was 375 ft wide instead of 32.5 ft. The system could never flow enough product to reach even 1 pound of NH3 to the acre with a 375 ft. wide applicator. It would however try and this would give high rates with no application rate displayed.