NAS 2000S I need to replace going bad fan...

[David Tigerino]

I have a NAS 2000S Storageworks unit. Lately we're getting error message of a bad fan. We purchace the new fan but we don't know how to find out wich fan is the one going bad,as they are not labelled inside the unit.
Could anyone tell me how to tell which fan is which? They all have green lights still. Is there is a PDF or any other file that could direct me in the proper way to do it. (if possible MOBO schematics).

I'd rather replace it now before it actually fails.

Thanks!