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FANUC Controller
Overheat/Thermal · Intermediate · 30-60 minutes
Fanuc Alarm 700 - System Overheat Warning
Fanuc Alarm 700 OVERHEAT: CONTROL UNIT indicates the internal temperature sensor within the CNC control unit has exceeded the allowable threshold, typically 55°C internal ambient. This triggers thermal protection to prevent damage to CPU boards, power supply modules, or I/O circuits. The alarm is generated by the internal thermal monitoring circuit on the main CPU board or power supply unit.
700
Fanuc Alarm 700 - System Overheat Warning
Overheating
Thermal protection alarm activated. The overheating has exceeded safe operating temperature and requires immediate attention to prevent component damage.
Root Cause Summary
Fanuc Alarm 700 OVERHEAT: CONTROL UNIT indicates the internal temperature sensor within the CNC control unit has exceeded the allowable threshold, typically 55°C internal ambient. This triggers thermal protection to prevent damage to CPU boards, power supply modules, or I/O circuits. The alarm is generated by the internal thermal monitoring circuit on the main CPU board or power supply unit.
Safety
- Allow cooling before continuing
- Check for fire hazards
Causes and Fixes
- 1
Check control cabinet cooling fan operation. Verify main cooling fan on control unit is rotating at full speed. Listen for abnormal bearing noise or reduced airflow.
- 2
Inspect and clean all air intake filters on cabinet doors and control unit. Replace disposable filters if clogged with dust, coolant mist, or debris. Clean washable filters with compressed air or water.
- 3
Verify cabinet air conditioning unit (if equipped) is functioning. Check set point is 35-40°C. Measure actual cabinet internal temperature using diagnostic thermometer.
- 4
Check exhaust vents are not blocked. Ensure minimum 150mm clearance around control unit for proper air circulation per Fanuc installation manual specifications.
Call a technician if:
- ·Internal component replacement required
- ·Thermal imaging shows multiple hot spots
- ·Alarm persists after all cooling system checks
Prevention
- Replace air filters every 3-6 months
- Maintain ambient temperature below 40°C
- Clean control cabinet annually
- Monitor cooling fan operation during daily checks
Common Mistakes
- Ignoring gradual temperature rise before alarm
- Using incorrect replacement fan specifications
- Blocking cabinet ventilation with stored materials
- Operating with damaged or missing air filters
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