A/C fan under hood

2000 monte carlo v6
dual climate control
a/c charged
a/c switched to high/recirc
fan on high
radiator fans do not turn on until motor gets to middle of temp gauge then they shut back off when the motor is cool.
shouldnt they immediately turn on when I turn on a/c?
what tells the fans to turn on for the a/c?
it works normal to cool the engine but the a/c function isnt telling them to operate correctly
compressor is on and spinning
slightly cool air coming out of the vents
please help im in miami I am going to die in this heat