Cooling fan

Cooling fans move air through a string inverter to carry heat away, and their speed changes with load and temperature. Spare-part lists show these fans as 24 VDC four-wire units, with three fitted per inverter. When a fan fails, the inverter raises the ExtFanErr alarm. Likely causes are a blocked fan, a fan at the end of its service life, or a fan socket connector with poor contact. First wait 5 minutes to see if the alarm clears by itself. If it stays, check the fan blades for foreign objects, switch the external AC disconnect off and back on, and contact post-sales service if the alarm remains. A failed fan is one cause of inverter overheating and temperature derating. Dust blocking heat dissipation and poor installation are other causes. If the vent is clean but the inverter runs too hot inside or makes abnormal noise, the external fans may need to be replaced. To replace a fan, remove the fan tray screws, unplug the fan's waterproof cable connector, fix the new fan and its cable to the tray, and refit the tray. Tighten the fan screws to 0.8-1 N.m and the tray screws to 1.2 N.m.

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• sentence 1: support check: partial - Passages state variable-speed fans operating by load and temperature, but not explicitly that they move air to carry heat away (implied by 'cooling'). -->