squeeling fan

i bought my '93 xj about a year and ahalf ago and noticed everytime I put the a/c on and then started to drive, i would hear a loud squeel from the fan belt section. It immediately stopped when i shut off the a/c.
Now i never really thought about this since the solution was to start driving then put the air on. sometimes i'll able to start driving then on its bad day it sqeeuls.
Anyone, know wat this is all about??

The belt tension is too loose.

The electric fan often comes on when the a/c compressor is engaged. Could it be that? It also could just be a bad pulley on the compressor.