Hunter Pro-C system zone issue

[madkiwi]

Went to start up and test our sprinklers and ran into an odd problem.

On zone 4 the water started but after two minutes it shut off. I thought that was odd and went back to the Hunter Pro-C controller, was surprised to see the zone was still showing active with 20 minutes left to run. I turned it off, then ran that zone again. Went out and observed the sprinklers were running, went to valve box and noticed a loud buzzing. After 2 minutes, yes, it shut off again and the buzzing stopped.

So I figured the solenoid was bad. Replaced it today, started the zone and no more buzzing. Yay! But guess what? After two minutes the water shut off again!

Went to the panel and tested voltage on the active zone to common, 26 volts AC even though the water is not flowing. Now I am stumped.

Anyone know what to look at next?

 

[Slomoola]

Isn't 26 volts AC sent to open each zone solenoid when it calls for water? Has to be as the solenoids are opened with magnetic force.

Went to the panel and tested voltage on the active zone to common, 26 volts AC even though the water is not flowing. Now I am stumped.

If the zone is active, you should have 26 VAC at the solenoid. Zone off should be 0 volts at the solenoid.

 

[Sponsor]

 

[ttthhh]

It might be the wiring at the solenoid. My old house had 13 zones. The company that installed it basically nicked at least one wire in every valve box. This didn't show up for years. As I recall, one year, after more than a decade, I had weird symptoms and finally tracked it down to a wire that had been nicked and was corroding and shorting to the ground itself. This happened because the installer used a tool to strip the multi-wire cable, but this also cut into many of the wires in the bundle. Once I fixed the problem zone, I went to every zone and found many that had the same issue, but had not started malfunctioning. I stripped back all the cut wires past the cuts and corrosion and used new outdoor rated wire nuts.