SULLAIR-MAIN-MOTOR-OVERLOAD critical Sullair WS Controller

Main Motor Overload — Relay Tripped

The SULLAIR-MAIN-MOTOR-OVERLOAD (Sullair WS Controller) diesel fault code means: Main Motor Overload — Relay Tripped. This is a critical severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
moderate
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Common Symptoms

  • WS display shows Main Motor Overload; machine faults and stays down

Probable Causes (Ranked by Likelihood)

  • Main motor overload relay tripped High
  • Load pressure set above the compressor's limit Moderate
  • Low line voltage Moderate
  • Incorrect compressor configuration Low

Step-by-Step Diagnostic Procedure

  1. The WS Controller is fitted to Sullair STATIONARY electric shop compressors. Portable towable Sullair units (185-class and similar) use different engine-driven controls and a different fault system — this page does not apply to them.

  2. Reset the overload only after the heater element cools down.

  3. Check that the compressor is properly configured and the load pressure is set below the machine's limit.

  4. Check line voltage — if low, the factory's advice is to consult the power company.

  5. Per the factory manual: after resolving a fault condition, press the STOP pad to clear the FAULTED state. If the problem persists after the recommended checks, consult your Sullair distributor or factory service.

Frequently Asked Questions

Can I just keep resetting it?

No — the overload exists to protect the motor. Repeated trips mean the motor is genuinely overloaded (pressure set too high, low voltage, or a mechanical drag) and resetting past it risks the motor itself.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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