S2 AC relay wiring

I’m reinstalling a factory AC system that was removed from my early 69 FHC many years ago by a PO. I have a questions regarding the power lead that goes to the C3 terminal of the AC relay. The wiring diagram show a brown/white (NW) wire starting at the B+ terminal of the Alternator and ending at the C3 terminal of the relay. That wire is missing from my car and even if it was there it is connected to the brown (N) wire from the Terminal post so would be hot all the time and not protected by any fuse.

Would there be any reason why I couldn’t run a wire from the fused terminal on Fuse No. 4 to the C3 terminal of the AC relay?

BTW I bought an AC wiring loom from Rhode Island wiring so have everything else I need, I just want to confirm the hot wire to the relay.

Thanks Andy

shouldn’t be a problem running supply from any fused source after ignition on, then you’re assure of no current draw when motor off…keep in mind that #4 supplies hazard flash can.

There are several relays used with A/C. Two are used for the fan:

The only power source for the fans is the green wire, which comes off Fuse 6.

The other relay is the main A/C relay. It’s powered directly from the B+ post on the alternator because it controls the fan clutch, which draws a ton of current. It’s not unprotected: when the relay engages, it’s protected by the inline fuse located behind the underdash unit. It’s a crappy design, but it works well enough.


I think this fuse was moved to the C3 side of the circuit when they redesigned for the S3, but I don’t have that schematic handy at the moment.

Thanks for your input guys.