The "NO AC" or "Blank" display is a diagnostic message telling you that the controller has stopped receiving AC power. For the "NO AC" message, the controller is most likely running on the power supplied by the backup battery.
Check the power source by plugging a lamp or radio into the wall outlet to verify there is power at the outlet. If your controller is not plugged into a wall outlet, the power source is hardwired.
Caution: High voltage testing on the transformers primary power side should only be done by a professional electrician or irrigation contractor.
If you have power at the outlet, the next thing to check is the transformer output. Use a voltmeter to check the voltage either on the two transformer wires or at the two AC screw terminals on the controller. The transformer should have an output in the range of 24VAC to 28VAC.
If the wall outlet has 110VAC and the transformer has no voltage output, you need to replace the transformer.
If you have voltage at both the wall outlet and the transformer output and you still have a blank display, try cycling the power on the controller. To cycle the power on the controller:
- Remove the 9-volt battery.
- Remove power by unplugging the transformer from the wall outlet or by turning off the circuit at the breaker box.
- Wait 4-5 minutes.
- Plug the controller transformer back into the electrical receptacle, or turn the breaker panel switch back on.
If this doesn’t restore the display, the controller will need to be replaced. If front panel will not light up with a 9V battery, then just the panel needs to be replaced.
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