neatolds

i have a 1980 olds cutlass calais and the blower fan works if i power it directly but not with the switch. the master selecft switch has three wires on it, a brown one,lt grn one and another brown one. one of the brown wires is suppose to power the fan speed switch,the other brown one goes to the ac fuse and resisters,and the green one goes to the ac pressure switch. my problem is one of my brown wires has been cut and i have heard of an in line fuse where is that fuse what i need is a wiring diagram for the ac blower system. any help would be appriciated thanks.