Hi all. I’m working on a 73 coupe with air conditioning and a small block engine. The AC /heater fan is powered by a wire from the AC / heater harness. There is a not connected orange wire in the ignition harness that is labeled as blower connection on the schematic.  

Would I be correct in assuming that this wire is only used to power the blower in a non AC car?  If that’s incorrect, how does it connect to the blower as there is only one hot connection and a ground. Trying to undo years of other people’s wiring changes. 

Thanks!

Not sure where this orange wire is on your car, but NON-AC cars have an orange wire from the fan switch that goes to both the fan resistor, and the blower motor.

NON A/C fan wiring

On A/C cars, you have an orange wire from the ign switch that runs thru the fusebox(25 amp), then it turns into a brown wire that goes to the A/C thumbwheel switch that powers the compressor, and the fan switch. You should also have an orange wire from the starter solenoid battery terminal to the junction box on the driver side fenderwell with a fuse-link that goes from the junction box to the high speed blower relay. Don't know if this helps, but....

I have the wiring diagrams on My Web Page

There is no diagram for the '73 A/C system, but the '74 diagram is the same.

Joel Adams
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Gotcha and thanks a heap for the information. This orange wire is in the ignition harness and was not connected to anything. The ac/heater harness makes all the connections to the blower, blower relay, thermal fuse, and compressor. There is no connection on the blower for this wire even though my schematic lists it as blower. At this point, Im pretty sure it only gets used with a non ac application.  Unless anyone has any other thoughts! Thanks again and I’ll download your schematics!