Sullair LS Series Error Code S005

Sullair Compressor Major Pressure

Model: LS Series | Code: S005

Applicable Systems
LS Series

Symptoms

Inlet valve (load/unload valve) is not responding to the controller command. The compressor either cannot load or cannot unload, causing continuous run or failure to build pressure.

Possible Causes

  • Inlet valve solenoid coil burned out or not receiving 24V DC control signal
  • Inlet valve pneumatic actuator diaphragm ruptured or piston seals worn
  • Inlet valve control air line kinked, blocked, or leaking
  • Inlet valve mechanical binding from carbon buildup on the valve plate

Troubleshooting Steps

  1. Step 1: Listen for the solenoid click when toggling load/unload from the controller test menu
    If no click, measure 24V DC at the solenoid terminals during a load command. Replace solenoid if voltage is present but no click
  2. Step 2: Remove the air line to the inlet valve actuator and apply 6 bar shop air directly
    The valve should snap fully open. If movement is slow or incomplete, rebuild or replace the actuator
  3. Step 3: Inspect the control air filter/regulator - drain moisture and verify output pressure is 5-6 bar
    Replace the filter element if saturated; adjust regulator to 5.5 bar if out of spec
  4. Step 4: Remove the inlet valve assembly from the intake pipe and inspect the valve plate and seat
    Clean carbon deposits with solvent; replace the valve plate if wear exceeds 0.5 mm

How to Reset

Reset: After repairing the inlet valve, perform a load/unload test cycle from the controller. The alarm clears when the controller confirms valve position feedback matches the command.

Common Replacement Parts

  • 2500-4100-00: Inlet valve solenoid, 24V DC (Direct-acting, 1/4 NPT, 10W coil)
  • 2500-4101-00: Inlet valve actuator rebuild kit (Diaphragm, piston seals, springs)
  • 2500-4102-00: Inlet valve plate and seat (Cast aluminum, Viton seal)

Frequently Asked Questions

  • Q: Can the compressor run with the inlet valve stuck open?

    Yes, but it will run continuously loaded, wasting energy and causing excessive wear. Do not operate for extended periods in this state.

  • Q: What pressure does the actuator need to open the valve?

    Typically 4.5-6.0 bar of clean control air. The solenoid vents this air to close the valve during unload.

Related Sullair Fault Codes

Source: Sullair LS Series Operation and Maintenance Manual, 02250141-841

Category: Compressor