There are two electric cooling fans for our cars or a two speed single fan not sure one speed is for normall operations and then the other one kicks in when engine is very hot, which is much louder than the regular one, the second one should cycle on and off, when engine temp rises then goes back down to normal temp. If it is extreamly loud it could be off balance, check the blades for blades cracked/damaged, or if there is any kind of undercoating on it.