1991 LeSabre Rear Defroster problem

It dosnt work. I see no cracks in the conductors on the window,no burnt wires that i can see,fuse is good. Does it have a relay and if so where would i find it in the car?? My GM book dosnt seem to cover it except the conductors,and the wire diagrams really confuse me. Thanx
Dave

Did you check the switch? If it is ok then, Start at the Load ( Window) and work you way back with a test light. Find where the power is being interrupted.

I did check the switch and it seems fine,are those two grey boxes by the airbox the relays??