Help! Converting an AC car to non AC wiring question

[Danco]

I am converting an AC car to non AC car. The question I have is, The section of the wiring harness that connected to the old heater box and control panel is not the same as my current heater box and panel. What do I need to do As far as getting the wiring corrected? Is the section of the harness I need available? Do I need to replace complete under dash harness?
Vehicle 74 duster was /6 AC and now is a 318 non AC car.
Any help or direction would be greatly appreciated.
Thanks
Dan

 

[ACME SS]

I am converting an AC car to non AC car. The question I have is, The section of the wiring harness that connected to the old heater box and control panel is not the same as my current heater box and panel. What do I need to do As far as getting the wiring corrected? Is the section of the harness I need available? Do I need to replace complete under dash harness?
Vehicle 74 duster was /6 AC and now is a 318 non AC car.
Any help or direction would be greatly appreciated.
Thanks
Dan

I see nobody has answered you so I will take a stab at this. My 71 was born with AC but someone converted it to heat only and I recently converted it back to classic auto air AC/heat. When they converted it to heat only, they changed out the heater core box (removed the evaporator box and replaced it with a heat only unit from a junker). There were some wire plugs (still are) that were not being used under my dash that I think were from the AC days. I guess what I'm saying is that you will probably only need the connector that goes to the fan switch and the one that goes to the fan motor. I believe the non AC fan is smaller in diameter and the hole in the firewall is smaller. I say that because the previous person had a goofy adapter plate inside behind the fan motor and when I went to install the classic auto air block off panel, it was too small and I had to fabricate my own. Oh, the fan plug for the heat only had 3 wires. A light green, dark green and a brown. I have that switch and the 6" harness if you need it, I can send it to you for free.

So to answer your question, I don't think you need a different harness but I could be wrong. I have several different schematics that I found online and none show a different version so probably just going to have an extra plug or two. Hope this helps. I wouldn't have even answered if someone else had but I'm feelin your pain.
Jerry

 

[ACME SS]

Well this is a screen shot of my 71 schematic but they are probably similar. It does not show a compressor clutch so I'm a little confused but perhaps they kept the colors the same and this might help you out hopefully.

 

[67Dart273]

Well this is a screen shot of my 71 schematic but they are probably similar. It does not show a compressor clutch so I'm a little confused but perhaps they kept the colors the same and this might help you out hopefully.
View attachment 1715917094

The 71 wiring is vastly different from 74, and even 73 is different from 74

Danco, I sent you a PM "conversation"

 

[Danco]

Hi ACME SS
Thank you for responding. Here is what i found out in a nut shell. AC system has its own dedicated harness. Easily removed. In my 74 duster at least the fan switch plug was already in factory harness but not used because the AC harness had its own plug. And I used the existing wires that went to heater box resistor. I have not tried it yet but see no reason it would not work. The 1 remaing thing i need is to
install a fuse on circiut #3 or #4 don't remember which at the moment.
Thanks Dan

 

[Danco]

I also modified the firewall to properly fit the new heater box and fan motor. I am relatively confident that I am allset with the wiring.
Thanks to you guys for chiming in and helping out.
Dan