Fan failure means the inverter's cooling fan has stopped working properly. Common causes are a blocked fan, a fan at the end of its service life, or poor contact at the fan socket connector. The inverter shows a fan alarm on its display: ExtFanErr on CPS units or Fan Fail on Solis units. Without working fans the inverter is not cooled properly, which can lead to temperature derating. First, wait about 5 minutes to see if the alarm clears by itself. Then check the fan blades for foreign objects and reboot the inverter using the external AC disconnect. If the alarm stays on while the fan is spinning, the sensing circuit is faulty and the inverter should be replaced. If the fan is not spinning, measure the voltage between the red and black wire pins at the fan connector. Below 6 VDC means the inverter should be replaced. Above 6 V means the fan should be replaced. Before you clean or replace a fan, switch off the grid, the AC power and the DC switch, then wait at least 15 minutes before removing the fan assembly. If none of these steps clears the fault, contact the manufacturer's after-sales service.
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affectsc1 verified · fact Cooling fan
tbl=38.r2 h=0fce0901dc0ctbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=33.r7 h=d0b0f2d02d90tbl=57.r3 h=432cb92c3d99verified by: review-workflowverified on: 2026-10-20
sec=7.2 h=08034ea4d7bftbl=33.r3 h=e1cf6ecb59decaused_byc3 verified · fact Fan obstruction
The fan is blocked, for example by foreign objects on the blades.
tbl=38.r2 h=0fce0901dc0ctbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99tbl=33.r8 h=e319683e4bbbverified by: review-workflowverified on: 2026-10-20
c4 drafted · lead Component aging
The fan has reached the end of its service life.
tbl=38.r2 h=0fce0901dc0ctbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99tbl=33.r8 h=e319683e4bbbc5 verified · fact Poor connector contact
Poor contact at the fan socket connector.
tbl=38.r2 h=0fce0901dc0ctbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99tbl=33.r8 h=e319683e4bbbverified by: review-workflowverified on: 2026-10-20
leads_toc6 verified · fact Inverter Overheating
Without working fans the inverter is not cooled properly, and it can derate because of temperature.
sec=7.2 h=08034ea4d7bftbl=33.r3 h=e1cf6ecb59deverified by: review-workflowverified on: 2026-10-20
presents_asc7 drafted · lead Fan fault alarm
Shown as ExtFanErr on CPS inverters and as Fan Fail on Solis inverters.
tbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99tbl=2.r1 h=2884c89a5021sec=7.2 h=08034ea4d7bfdetected_byc8 verified · fact Visual inspection
Check whether the fan is spinning and whether foreign objects are on the blades.
tbl=38.r2 h=0fce0901dc0ctbl=33.r3 h=432cb92c3d99tbl=2.r1 h=2884c89a5021verified by: review-workflowverified on: 2026-10-20review note: support check: partial - u1 mentions 'by visual check', u2 says to check for foreign objects on the blades, and u9 says to check whether the fan is spinning. The passages do not explicitly describe visual inspection as a detection method.
c9 drafted · lead Inverter display check
tbl=2.r1 h=2884c89a5021sec=7.2 h=08034ea4d7bfc10 drafted · lead Fan supply voltage measurement
Measure across the red and black wire pins at the fan connector while the fan is not spinning.
tbl=2.r1 h=2884c89a5021tbl=31.r1 h=2884c89a5021tbl=55.r1 h=2884c89a5021distinguished_fromc11 drafted · lead Internal power supply fault — told apart by Fan supply voltage measurement
If the fan is stopped and its supply voltage is below 6 VDC, the fault is inside the inverter and the inverter should be replaced. If the voltage is above 6 V, the fan is at fault and should be replaced. If the fan spins but the alarm stays on, the sensing circuit is faulty.
tbl=2.r1 h=2884c89a5021tbl=31.r1 h=2884c89a5021tbl=55.r1 h=2884c89a5021review note: support check: partial - The voltage thresholds and the sensing circuit case are stated. The passages do not mention an 'internal power supply fault' concept, only replacing the inverter when the voltage is low.
mitigated_byc12 drafted · lead Clear ventilation blockage
Remove foreign objects from the fan blades or clean the fan.
tbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99sec=7.2 h=08034ea4d7bfc13 drafted · lead Inverter restart
Turn the external AC disconnect off and back on to reboot the system.
tbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99c14 verified · fact Fan replacement
tbl=2.r1 h=2884c89a5021tbl=31.r1 h=2884c89a5021tbl=55.r1 h=2884c89a5021sec=7.2 h=08034ea4d7bfverified by: review-workflowverified on: 2026-10-20
c15 verified · fact Inverter replacement
Applies when the fan supply voltage is low or the sensing circuit is faulty.
tbl=2.r1 h=2884c89a5021tbl=31.r1 h=2884c89a5021tbl=55.r1 h=2884c89a5021verified by: review-workflowverified on: 2026-10-20
c16 verified · fact Contact manufacturer service
tbl=33.r3 h=432cb92c3d99tbl=4.r3 h=432cb92c3d99tbl=57.r3 h=432cb92c3d99verified by: review-workflowverified on: 2026-10-20
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