Hi CL members like I was mention about the fan noise behind my NAV unit, so today I took some time to remove the NAV unit and discovered on our NAV radio unit has 2 cooling fans the top side one is for the LCD cooler fan and the one on the bottom is for the whole unit cooling fan, so it not happan to everyone? but it was happen on me, anyway when my car is parked in the hot wheather or after the radio play for a little while and the cooling fan kick in when the unit is hot and that fan is rubbing the fan frame that is where the noise came from so all I did is loose two crews that hold the fan in the unit a little and it fix that noise problem it is not happen to any of the CL member yet, but it happen to me here is some pics that I took while the unit is out.

 

Thats awesome you found your problem