Atlas Copco ZR & ZT Oil-Free Compressor Fault Codes: Troubleshooting Guide

troubleshootingGreg Aiken
Atlas Copco ZR & ZT Oil-Free Compressor Fault Codes: Troubleshooting Guide

Atlas Copco ZR/ZT Oil-Free Faults: What They Mean and How to Fix Them

Atlas Copco ZR/ZT oil-free rotary screw compressors are built for clean air and critical applications. When the Elektronikon throws a message, you need fast, safe steps to get production back online. Use this guide to decode common ZR/ZT faults, run first checks, and decide when to bring in a technician.

Applies To

  • ZR (oil-free, water-cooled and air-cooled variants)
  • ZT (oil-free, typically air-cooled)
  • Elektronikon controller generations commonly used on ZR/ZT units

Before You Start

  • Lock out and tag out power before opening panels.
  • Record the exact fault text or code and what the machine was doing when it occurred.
  • Do not clear service timers unless the maintenance has been performed.

Oil-Free Realities That Affect Faults

  • Cooling is everything: ZR water flow/temperature and ZT airflow make or break temperature stability.
  • No oil film as a buffer: Sensor accuracy and proper sealing are critical; small issues show up quickly as trips.
  • Instrumentation heavy: Parameter integrity and clean communications matter more than usual.

Most Common ZR/ZT Controller Messages

1) High Discharge Temperature / Element Temperature

  • Meaning: Compression temperatures exceeded limits.
  • First checks (ZR water-cooled): Verify adequate cooling water flow and pressure, confirm inlet water temperature, remove scale from heat exchangers, open isolation valves fully.
  • First checks (ZT air-cooled): Clean coolers and intake screens, verify all fans run and spin the correct direction, ensure ventilation is not recirculating hot air.
  • Also check: Thermistor wiring and connectors for damage or looseness.

2) Drive Not Healthy / VSD Trip (A017 or similar)

  • Meaning: The drive reports a fault or will not come ready.
  • First checks: Clean power cycle, inspect drive keypad LEDs, reseat interface board cables, confirm cabinet fans operate, check ambient conditions.
  • If it persists: Verify incoming power quality, look for parameter mismatches after board or drive swaps, review drive trip history.

3) Communication or Converter Timeout

  • Meaning: Lost communications between the Elektronikon and the drive or converter modules.
  • First checks: Reseat low-voltage comm cables, inspect for abrasion or corrosion, confirm the service switch position, perform a full power down so the controller and drive boot together.

4) Parameter Fail / Format Fail

  • Meaning: Parameter corruption or mismatch detected.
  • First checks: Confirm correct service/run position. If a component was replaced, reload the proper parameter set from a known good backup. Do not enter guessed values.

5) Motor or Inverter Overtemperature (F011, F006)

  • Meaning: Either the motor windings or the inverter heat sink is too hot.
  • First checks: For ZR, verify cooling water flow and heat exchanger cleanliness. For ZT, clean heat sinks, confirm fan operation, and ensure cabinet ventilation is clear.

6) Overcurrent / Overvoltage (F020, F023)

  • Overcurrent checks: Inspect for mechanical binding, check that the inlet valve actuates freely, verify no downstream restriction is forcing load spikes.
  • Overvoltage checks: Measure mains voltage, confirm utility stability, and verify braking resistor circuit on VSD units.

7) Run Enable Open / Interlock Open

  • Meaning: A permissive is not satisfied.
  • First checks: Emergency stop released, door switches closed, external run signal present, safety circuits intact. Trace the input through the I/O to find the open contact.

ZR Water-Cooled: Targeted Checks

  • Measure inlet and outlet water temperatures and pressure. Compare to spec.
  • Check strainers for debris and verify valves are fully open.
  • Inspect heat exchangers for scaling; clean or descale as required.
  • Confirm cooling tower or chiller setpoints provide adequate approach temperature.

ZT Air-Cooled: Targeted Checks

  • Clean condenser surfaces and cabinet filters.
  • Verify each fan runs at the expected speed and correct rotation.
  • Eliminate hot-air recirculation; redirect exhaust or add make-up air if needed.

Fast Checks That Solve Many Oil-Free Trips

  • Reseat low-voltage connectors on controller, I/O, sensors, and drive.
  • Verify accurate temperature and pressure readings by cross-checking with a known good gauge when possible.
  • Confirm interlocks and external run enable are satisfied.
  • Perform a clean power cycle and allow full boot before start.

Recommended Preventative Maintenance Parts

When To Call a Technician

  • Repeated drive trips or parameter errors after basic checks are complete.
  • Evidence of controller or board damage, arcing, or persistent sensor faults.
  • Cooling system limitations that require system changes (tower, chiller, ducting).

Related Reading

For repeat trips on stationary oil-free units, bring in a pro to verify parameters, cooling performance, and drive health.

Disclaimer: The information provided in this blog is intended for general troubleshooting guidance only and may not cover every situation or machine configuration. Always refer to your specific equipment’s manual and follow the manufacturer’s safety instructions. If you are unsure or uncomfortable performing any maintenance or repairs, consult a qualified technician. Air Compressor Services is not responsible for any injuries, damages, or losses resulting from the use of this information.