Lower fan speed on Arris C4c?

Hi!

A customer has a couple of C4c's and in two places, the noise is a bit overwhelming. We do have the following in the config:

fan speed-control no shutdown

I have also issued the following:

configure fan monitor 0 no shutdown
configure fan monitor 1 no shutdown
configure fan monitor 2 no shutdown

I assume there is not much else to do, but perhaps someone out there has a special trick for lowering the fan speed. We just need a notch lower noise to please the occupants of the surrounding localities. Sound proofing the cabinet is another option. Worst case we'll have to "adjust" the fan modules electronically...

The rooms where these units are located are properly cooled to some 20 degrees celsius.

Thanks!

/Fredrik