What causes FANUC alarm 603?

Excessive cutting load or feedrate causing high motor current. Inadequate or blocked cooling for the servo amplifier. Worn or damaged servo motor bearings causing increased friction.

How do I fix FANUC alarm 603?

1. Allow the servo amplifier to cool down by powering off the machine for at least 30 minutes. This will reset the overheat alarm. 2. Check the cooling fans and air filters on the servo amplifier and clean or replace as needed to ensure proper airflow. 3. Reduce the programmed feedrate or depth of cut to decrease the motor load and heat generation. 4. Inspect the servo motors for any signs of bearing wear or damage that could be causing increased friction and heat. 5. If the alarm persists, you may need to replace the servo amplifier or motor to resolve the overheating issue.

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FANUC Controller

Servo/Axis · Intermediate · 30-60 minutes

Alarm 603

Fanuc Alarm 603 - n AXIS: INV. IPM ALARM (OH)

Fanuc 603 INV. IPM ALARM (OH) indicates the Intelligent Power Module in the servo amplifier has detected an overheat condition and shut down to protect itself. This is typically caused by inadequate cooling airflow, excessive motor load, or amplifier internal failure. The alarm will not reset until the IPM temperature drops below the threshold.

FANUCServo/AxisIntermediate30-60 minutes

603

Fanuc Alarm 603 - n AXIS: INV. IPM ALARM (OH)

SYSTEM ALARM 603

Root Cause Summary

Fanuc 603 INV. IPM ALARM (OH) indicates the Intelligent Power Module in the servo amplifier has detected an overheat condition and shut down to protect itself. This is typically caused by inadequate cooling airflow, excessive motor load, or amplifier internal failure. The alarm will not reset until the IPM temperature drops below the threshold.

Causes and Fixes

1
Power down the machine and wait 30-60 minutes for the IPM to cool completely. Verify the alarm resets after cool-down by checking DIAGNOSIS screen > SERVO > ALARM HISTORY.
Do not repeatedly power cycle while amplifier is hot - this can damage the IPM permanently
2
Inspect all cooling fans on the amplifier cabinet (control and power side). Verify fans spin freely and check for proper rotation direction. Replace any failed fans immediately.
3
Clean all heat sinks and ventilation openings with compressed air. Check air intake filters and replace if clogged. Verify cabinet ambient temperature does not exceed 55°C (131°F).
4
Monitor amplifier temperature using DIAGNOSIS > SERVO > TEMP display after restart. Normal operating temperature should be below 70°C for most amplifier modules.

DIY Feasiblehigh confidence

Call a technician if:

·IPM insulation test fails
·Amplifier replacement required
·Persistent overheating after cooling system repair

Prevention

Regular cooling system maintenance
Monitor amplifier temperature trends
Avoid continuous high-load operation
Maintain proper cabinet ventilation

Common Mistakes

Ignoring gradual temperature increases
Operating with blocked air vents
Setting excessive servo gains
Not allowing cool-down time between high-demand cycles

Related Alarms

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