only the hevac to get working

calling all electronic guru,s,i,ve done the heater matrix o-rings,fixed a starting problem and today changed the front air-bags,all only with the help of you beautifull people.but the last jobs doin my head in,,the blowers don,t work at all.they did but intermitantly,now nothing.i,ve read somewhere about the fuse box overheating and burning the relays out-mine shows no sign of that,i,ve also read about bypassing the relays due to a bad earth from the becm?how would i go about that?i have a volmeter but have,nt a clue what terminals to check in the fusebox.i,ve taken the cover off a relay to see if the contacts are mating and theres nothing so i presume theres a bad earth/feed.any ideas much appreciated