During commisssioning OSN1500 subcontractor told, that fan doesn't work. Also OSN reported Fan_fail alarm. There was suggestion to change the fan.
If you found problem with fan, fist need to check are any foreign objects into the fan. If objects were found need to unplug it and after fan can work normally.
After unpluging the fan foreign object was found inside the fan. So subcontractor removed the foreign object and inserted fan into OSN. Fan started the work and alarm disappear.