SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Here's the deal...whenever I turn the sprinkled system on either manually or electronically one of my control valves has a loud "hum" the entire time its running. The additional issues are that the timer box doesn't shut this zone of automatically which requires me to be around whenever the system is running and to subsequently shut the water off completely (after water main) in order to eliminate "hum". I am fairly new to the irrigation game and this irrigation system had been installed 10 yrs prior to my family moving into the house. That said...the valvesnare made by Nelson (no idea which series) and the solenoid has the following info stamped on it: 24 VAC 50/60 Hrz Inrush .50 amp. Holding .23 amp. Any assistance would be greatly appreciated! Thanks in advance