wipers won't work--HELP
 

I have my Dad's 1986 F150 Lariat w/5.0 V8. Two days ago when I switched the wipers on, nothing. The washer control is on the same switch (push-in), and washer works perfect but when I turn the wiper switch, either intermitant or slow/fast, I can here clicking in a small box lacated near the fuse box but the blades will not move. My Haynes manual does not show a fuse or relay for the wipers.Is there a fuse or relay for the wipers or should I be looking at the wiper motor or maybe even the switch? Thanks