All my sprinklers worked about a month ago. However, now one of my six zones are not producing enough pressure; all the other zones work just fine. I checked the voltage for this problematic zone and it was around 25 VAC. The resistance is around 60 Ohms. So, it seems that the solenoid is just fine (please correct me if I am wrong). Question:
- Am I correct in my hunch/diagnostic that it is the zone-valve and not the solenoid or sprinkler head that are the problem?
- What is a good way (diagnostic) to find out which zone-valve is busted?
- What should be my next steps?
I want to make sure that I am reasonable accurate since the zone-valves have not been touched in the past 20+ years and hence have a lot of dirt/mud on them; besides, they are each in 10-inch diameter plastic canisters under the ground (making access rather difficult).