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New Member


Thursday, July 28th 2016, 3:51pm

Hunter Pro-C - No Voltage to AC1, No Voltage to Any Zones, 25A to AC2


I'm having trouble with my Hunter Pro-C sprinkler system. The valve for zone 1 does not close, and its below-ground housing hole floods when main valve is manually opened. Took all valves apart and checked diaphragms. No issues, clogs, or debris. Used a volt ohm meter. No voltage going to any of the zones. Tested the GND, AC1, and AC2. 25 amps are going to AC2, none to AC1. Borrowed neighbor'ss AC adapter and attached. Same issue, voltage to AC2 but none to AC1. The control panel display remains on without a battery in the unit.

What does it mean if theres no voltage going from the AC adapter (with two tried) to AC1, and would that be the reason that voltage is going to the control display but not to the zonal outputs?

Can't find any information about the difference between AC1 and AC2. My assumption is AC1 is the circuit board for the zonal outputs and AC2 goes to the control panel display. Though, that's just my best guess.

Any thoughts on how to fix or is it best to replace the entire control panel?



Posts: 2,365

Location: USA


Friday, July 29th 2016, 3:34am

The flooding is probably from a cracked valve. Find the flood and fix it.

Try testing AC1 and AC2 together. Place the leads to AC1 and AC2 and nothing else. What reading do you get? In volts. That's where the transformer wires connect.

Taking out the battery alone wont make the display blank. You have to unplug it too. Sometimes it takes a couple of minutes to run down.


New Member


Friday, July 29th 2016, 7:08am

The troubleshooting manual says to test AC1 and AC2 with the GND connect, doing so reads 24 volts to AC2 and 0 volts AC1.I'll try AC1 and AC2 together, but I'm not sure how that would give me a reading to one versus the other. Is my suspicion correct, that AC1 powers the zone circuit board, hence the zonal outputs, and that AC2 powers the display panel? That would explain why the display works but there is no power going to the circuit board and/or the outputs. Tests of all outputs shows 0 volts.

Even if there was a cracked valve--the crack would have to be small enough that I can neither see nor feel it--the valve would shut if the solenoid were not getting power. Despite the crack, such a small crack would not cause the solenoid to keep from closing and therefore the system to not switch zones.

I may change the valve anyway, but I'm more interested in why theres no power going to the zonal outputs and whether AC1 controls the circuit board for the zones and AC2 controls the front panel. There is no battery in the system, but that would explain why without the battery, the display is getting power but the zonal outputs are not.


Supreme Member

Posts: 5,323

Location: Metro NYC


Friday, July 29th 2016, 8:23am

Forget the ground. Sprinkler controllers can work just fine without a ground wire. The transformer output is measured from AC1 to AC2 and that's it.

If you think you have electrical issues, you have to stop with the voltage readings and step up in class. Resistance readings of the field wiring (one test lead on the common wire, one on a zone wire {go ahead and disconnect the common wire from the controller before the testing}) are the next logical step, and AC current readings of the operating zones are the most revealing measurement.

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