I think FAU means Forced Air Unit, but a different one says AC. Why would there be both?

There are also two separate ones that say W.A. What is that?

From top to bottom they say:

A.C. (two connected; each with number 40); 
DISH & DISP (two connected; each with number 20); 
WASH (20); 
F.A.U. (20); 
W.A. (20); 
MAIN (two connected; each with number 100); 
W.A. (20); 
PLUGS & LIGHTS (one label for next last 5, separate, labeled '15'); 
and two more, connected with no label each with number 50