Have 2016 Z06 for 3 years Never heard sound but on extended trip a fan would go on and off while driving and somewhat loud. Don’t think it’s the cooling fan. Any idea what it is?

 

Welcome to the forum, You could try shutting down the HVAC system when you hear the fan noise to see if it stops. If it does then that's probably a indication that it's the blower motor. The only other thing I could think there might be is one for a cooling system for the radio but not sure.

 

Check the fan blade for any damage because that may cause a different sound and if it's proper keep your engine in idle for 30 minutes and if the fan doesn't switch 'on' there's a problem with the fan check it out immediately.(if it is cooling fan)