I have a rc8.2e. Does the fan only kick on when its hot or does it always run?

Only comes on if it gets over a certain temp. Like 120 or so.

It will flick on when you initially turn on the ESC then only come back on if you creep up to 140. IMO if your running the "Right" gearing and aren't a HAM fisted driver you really dont need a Fan on the ESC. Ive ran my RX8's for Years without fans.