Cooling fan failure

Cooling fan failure means the inverter's external cooling fan no longer works properly. Inverter manuals give three possible causes: the fan is blocked, it has reached the end of its service life, or its socket connector makes poor contact. The fan runs at variable speed according to inverter load and temperature, so a failed fan reduces cooling just when heat output is high. Fan failure is one of the listed causes of inverter overheating, which leads the inverter to derate its output because of temperature. Fan problems such as a blocked fan, a worn-out fan or a poor fan connector are also listed as causes of an inverter over-temperature protection event. Signs in the field are a high internal inverter temperature or unusual fan noise. If the air vent is clear and clean, the external fans may need to be replaced. When the fan alarm appears, wait 5 minutes to see if it clears on its own, then check the fan blades for foreign objects. If it is still active, reboot the inverter by switching the external AC disconnect off and back on, and call post-sales service if that does not fix it. To reduce the risk of overheating, inspect the ventilation units regularly, use adequate cooling technology and monitor inverter temperature.

<!-- review notes

• sentence 2: support check: partial - The passage says the fan operates on load and temperature with variable speed, but the consequence that failure reduces cooling when heat is high is an inference not stated.
• sentence 5: support check: partial - Passages say high internal temperature or abnormal noise with a clear air vent may require replacing external fans, but they don't call these 'signs of a fan problem' beyond that; abnormal noise is not specifically 'fan noise'—minor, core is stated. -->