2000 mercery villager

i have a 2000 mercury villager with 170,000 miles on it runs great only problem is that i cannot get the blower to work so that i have heat or air. it was last week but 1,2,3 on the dial didnt work only on high. but so far i have checked fuses and relays that are under the dash and under the hood i have checked to see if it was getting power to switch but no luck all read 0volts so i have a problem from the fuse box to the switch i have heard that there are two circit boards behind where the radio is and i have not located them but i am out of things to check is there any thing i missed other than finding the two circit boards? any help is greatly appreciated i have a 1 year old that has to ride in the van so need answers asap thanks