Well I tried fixing my nonexistant heat by first replacing the control unit with a newer looking one from the jy, didn't work, re soldered the old unit, didn't work, cleaned the fuse and terminals, that actually worked, for about 2 trips, I made sure it was really clean after that with no success. So I would like to fix it correctly but right now its really friggin cold driving this thing. Can I jump two prongs on the control unit plugs to get the blower to blow full blast? All I can find is a schematic from an 86 SDL and it says term 13 is hot, I dont have 13 terminals. Oh mine is an 81 sd.