Fanuc Parts Specialists

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Cause: This is a control system fault in which the FANS on the CNC control system are problematic. This can be the fans stopping, or not rotating properly or the power to the fans are a problem depending on the CNC control on your machine.

In most cases the fanuc motors are fitted in the top sections of the control system. With each fan being fitted with a sensor circuit which allows the Fanuc CNC to detect any problems with the fan and issuing both the 701 alarm and in other controls the ‘FAN’ tag on the bottom of the CRT or LCD display.

Certainly as a first action, identifying the fan is important. Please note there is a Fanuc part number for the fan (this is the better part number) and the fan manufacturers part number which only details the fan itself without connector necessary for Fanuc control.

  • 16/18/20/21 A/B/C controls use either dual slot fans or single slot fan
  • 16i/18i/21i and other earlier 0i/3xi controls use smaller fans that clip in above the control system
  • Later 0i and 3xi controls use cartridge fan systems.

Solution: Normally changing the fan (please read about identifying above). However we have come across problems causing the fan alarm that was not the fan faulting out, but its power circuit.

Note: Some information on various forums and self help video’s guides while well intended in most cases about alarms can be utter rubbish; leading to spending hours chasing bad advice – please be careful. If you feel your out of your depth either electrically, mechanically, electronically or with the application sides of the CNC control, drives, I/O and the machine itself; please consult and employ the services of a trained CNC service engineer!

Fanuc Parts Specialist:

If your Fanuc control system displays a 701 alarm then we can help by assiting with diagnosis and the supply of parts or repair of drives, motors and control systems. Further we can supply fans if required.

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