Maintenance, Troubleshooting, and Repair
Diagnosis and repair
Troubleshoot from the source outward: supply pressure and flow, then backflow device, mainline, valve, lateral, head. Measure rather than guess - a pressure gauge at a hose bibb and an ohmmeter solve most service calls.
Common signatures: one dead zone among working ones points to a station wire, solenoid, or diaphragm. All zones dead points to the common wire, transformer, or controller. A geyser at the lowest head means a broken lateral or riser. A valve that will not close usually has debris on the diaphragm seat or a torn diaphragm; a valve that will not open has a failed solenoid or no 24 VAC at the coil. Solenoid coils typically measure 20–60 ohms; open or shorted readings mean replacement.
Water in the valve box, hunched heads, and dry spots often indicate low pressure or an upstream leak, not a bad nozzle. Watch for misting (pressure too high) and runoff or tunneling (application too fast for the soil).
Seasonal service: blow lines with air below the pipe rating (commonly ~50 psi for poly, and never through a backflow device), drain valves and pumps, and remove or protect sensors.
Worked example: a zone reads 45 psi static at the valve but far heads barely pop. That reading is meaningless without flow - check the valve strainer and lateral for partial blockage before replacing heads.