Atlas Copco Y1 load solenoid valve

Elektronikon-driven pilot solenoid on GA/GX screw units. Energise Y1 = load, de-energise = unload plus blowdown.

Also called: Y1 · loading valve GA · solenoid valve 1089 series

Energised to load. Elektronikon logs 'Load solenoid' output state — compare the logged output against measured coil voltage.

How it works

Elektronikon energises Y1 when net pressure drops to the loading setpoint. Control air from the sump passes to the unloader/inlet-valve piston, forcing the throttle disc open. On unload Y1 drops out, the piston vents and the blowdown port dumps sump pressure to about 30 PSIG through the vent.

Coil resistance (typical, cold DC)

Typical values for the stated wattage class. Always compare against the coil tag. Open circuit = burnt winding; near 0 Ω = shorted turns.

Specifications

Typical part family

1089 0577 xx / 1089 9576 xx solenoid + coil

Connector

DIN 43650-A, 3-pin with earth

Control air

Sump pressure, filtered through a 20 µm pilot strainer

Parts you can order

• Atlas Copco (OEM)

  Y1 loading solenoid valve

  Serial-specific (1089 0577 xx / 1089 0621 xx families)

  $150 – $480

Field test procedure

1. Read the Elektronikon digital output state first — if the controller says LOAD and there is no 24 V at Y1, the fault is upstream (output board, fuse F, wiring).
2. Ohm the 24 VDC coil: 30 – 55 Ω typical. Open or shorted = replace coil.
3. Check the pilot strainer in the control air line — varnish blocks it long before the valve fails.

Symptoms & probable causes

• Runs unloaded only, pressure never builds
  Y1 not energised, coil open, or inlet valve stuck shut.
• Will not unload at setpoint, safety valve lifts
  Y1 stuck passing, or the blowdown solenoid/orifice is blocked.