HELP A/C heater switch

So in one drawing both blower and clutch coil power is supplied by a single fuse and wire ( smells of circuit overload to me ). The other drawing shows power supplied by 2 seperate circuits.
As for the temperature control switch.. If the compressor runs without the blower running at least at low speed the vaporater coil would ice over in a hurry.
That's also why the 73 and later systems fan switch doesn't have an off position. Selecting any form of climate control results in minimum low speed fan on.
I'll have to study this a bit to determine what exactly caused the change.