KRC0118

Common Causes

• Blocked or obstructed cooling fan intake/exhaust vents on the KRC4 cabinet preventing adequate airflow through the power section
• Failed or degraded cooling fan in the power module section, running at reduced RPM or completely stopped due to bearing failure or electrical fault
• Excessive ambient temperature in the cell exceeding 45 degrees Celsius or inadequate facility HVAC cooling around the control cabinet
• High continuous axis loading or rapid duty cycles causing sustained high current draw through power modules without adequate cooling periods
• Accumulated dust, dirt, or debris buildup on heat sink fins and internal cabinet surfaces reducing thermal transfer efficiency

Troubleshooting Steps

1. 1Step 1: Acknowledge alarm and allow 15-20 minutes cool-down period while monitoring ambient temperature around cabinet, ensure it is below 40 degrees Celsius
2. 2Step 2: Open KRC4 cabinet and verify all cooling fans are operational by visual inspection during power-up, check fan connectors X701-X704 on KPP for secure connections
3. 3Step 3: Inspect heat sink surfaces and cooling air pathways for dust accumulation, clean with compressed air and vacuum if necessary, paying attention to finned surfaces
4. 4Step 4: Access Service menu and check KCP System Info to review thermal history and actual temperature readings from diagnostic variables $heat_sink_temp or monitor analog inputs
5. 5Step 5: Review program for excessive acceleration values, short cycle times, or continuous high-speed operation that may be thermally overloading specific axes without dwell time
6. 6Step 6: If alarm persists after cleaning and verification, measure fan voltage at connectors (should be 24VDC), replace defective fans, or contact KUKA service if power module thermal sensor or KPP hardware fault is suspected