Need the group 's help with this simple challenge.
The PO wired in a toggle switch which was non working when we got the car. I have NOS switch coming which has four prongs. Three of these appear to plug into throw three wire harness on the top left side of the heater box. There is a "key on" wire from the ignition switch without a home and we assume this goes to the fourth prong on the NOS switch. This is a non A/C unit.

Also, need to know vacuum line routing.

Schematics would be helpful if anyone has them.