hey newbie here have 2 questions concering my 2004 trx quad

well was curious today was riding my quad which is 2004 honda 450trx and it got pretty hot temp outside was like 90 and i noticed for the first time the fan was coming on but turning very slow very slow is that normal or is it suppose to spin fast ? the quad runs great !! and how often are you guys changing the coolant fluid in these ? and what do you guess reccamend to put back in the raditor / thanx for your time ........