Siemens alarm 3: Fan failure

What it means

Fan monitoring detected incorrect fan operation in the control housing. As with overtemperature, safe hardware function is no longer guaranteed and a contact on the CSB opens for external measures; machining continues in the short term, so the fan should be serviced promptly to avoid thermal shutdown or damage.

Likely causes

• Worn or seized cooling fan
• Fan cable unplugged
• Blocked ventilation slots/filters

Replacement parts

We supply the following units for this alarm — tested, warranty-backed:

• 840C housing fan per spare-part list

  fan · Check if others ruled out

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