what is the cause of the noise and vibration? what do you think needs replaced or repaired. How much is the cost? is this something that's needs to be replaced if my son can withstand the noise or will it eventually get worse and quit working?
My car has 75000 miles.
My car has an automatic transmission.
It sounds like you either have damage to the fan assembly, making it out of balance, or you may have some sort of object like a dead rodent, that is making the fan shake like an unbalanced tire. This will always get worse with higher fan speeds. I suggest removing the fan assembly and inspecting it for damage, debris, or unwanted visitors. If you want to have this checked for you, a certified technician, like one from YourMechanic, will be able to inspect the noise and replace your fan assembly if needed.