fuse burning problem!

hey guys, well my 94 4.3 lt1 caprice classic runs perfect! it has 208,656 miles!!just one little problem 1:it burns 2 fuses one that controlsthe pwr mirrors and locks and the other that controls the 2nd fans,it is on the passanger side fire wall a 40 amp.I changed them once and they blew within an hour.any comments would help thanks guys this is my first caprice and hopefully not my last.

Do they blow while they're in use or at any random time (about an hour) while the cars running?

first fuse power mirrors: this doesent seem to me to be a "High Load" device so you may be experiencing a short, try to locate the wiring for the mirrors and see if there is a portion grounding out or touching another wire.

second fuse: your blower motor? or your radiator fans?
if its your blower motor you may have a burnt out resistor pack.
if its your radiator fan make sure it too is not grounding out, also make sure the wire supplying power before and after the fuse block is of sufficient gauge to handle the load. if you have a relay attached to this system (i would hope) you may have a bad relay that just grounds out.
if you do not have a relay i would suggest getting one to handle the power going to the fan... this can save headaches from having to replace burnt out fuses and switches

thanks alot dude ill try the relays and see what happens!!!