aux fan fuse box .mounted in eng compartment . behind main fuse box . question is I have a red wire from fmain fuse box hot all the time . and a blue wire .and a black one. in Mercedes wiring diagram from batt bus to one end of fuse box f20 . theres a bk /rd wire . tthen on other end of fuse box .theres a red and blu wire going to aux fan relay . this f20 box has 2 separate fuses and I only have 3 wires . and trhe wires are black . blue and this red coming fr fuse boxmain ? cant find the main fusebox in Mercedes electrical troubleshooting manual .trying to post diagrams and pictures