Try this :

to get fan speed for card 0
export DISPLAY=:0.0; aticonfig --pplib-cmd "get fanspeed 0"

to get fan speed for card 1
export DISPLAY=:0.1; aticonfig --pplib-cmd "get fanspeed 0"

to set fan speed for card 0 to 50%
export DISPLAY=:0.0; aticonfig --pplib-cmd "set fanspeed 0 50"