Heat versus AC/heat box interchange

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Neal Zimmerman

Neal Zimmerman

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When I got my 68 Cuda ( factory AC car) most of the AC stuff was long gone. And I have no interest in replacing it. BUT the heater/AC box that was in there was absolutely destroyed,
worst I have ever seen. So I just took it out. Currently I am heaterless.
I want to put a heat only box in there, and I wonder if there are any obstacles to doing
that? Do the heater core holes come out somewhere else on the firewall, for instance. How about the blower motor? Will an AC car blower motor work or were they different?
I know the dash bezel controls would be different but I have that covered. I found a non AC dash panel.
Neal
PS If anybody needs any of this AC stuff let me know. What I can't use, I am getting rid of.
Under dash Diffuser for instance, and pushbutton dash controls. In good shape, all nipples intact
 
The AC vs heat only use different firewall holes. Probably the firewall is a totally different part.

Heat only
Screenshot_20220710-193308.png


AC (fan motor is different, ac lines to right of heater lines)


Screenshot_20220710-194812.png


That's not to say that you couldn't fill holes and make new ones
 
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Yes the heater core is different, thus the firewall holes different. Box is different as well I believe. We have a 67 AC car, but I didnt want any of the underhood stuff in the way. AC box, controls and diffuser installed in car.
 
It appears to me from those two pics that the heater core outlets are in the same place.
When I swapped engines I filled in the holes for the AC lines .
 
My recolection is that the heater motor hole is different, can't say about the heater holes. 1/2 inch difference will make or brake things.
 
Wow? Yes that heat only blower is certainly smaller. It would be quite a project and one that looks like it would be easier to yank the motor to do it.
 
Neal Zimmerman said:
It would be quite a project and one that looks like it would be easier to yank the motor to do it
Click to expand...
You could make a filler plate and just sandwich it in the assy, using the AC motor holes and the heat only motor holes.

Kind of redneck but it could be done gracefully with a flat plate with rolled over edges and a couple of gaskets.
 
I went the other way, put factory ac in a non ac car. Firewall mounting hole are different, I had to cut out fan hole much larger, controls are different. It should be a lot easier going your way.
 
IMG_0018.jpg


I went Non Ac to Ac The Black outline it the fan motor hole for the ac box so you will have to make an adapter plate. The heater core comes out in the same place. You will have to plug the two holes top right where the ac lines come out
 
Even if you wanted to go aftermarket A/C, the factory A/C cars are a problem. The aftermarket companies only make units for non A/C cars. So filling holes will be required.
 
are the mounting studs in the two boxes even remotely the same? I don't think so... I have been running an A/C box with all the A/C stuff removed from the box and an A/C heater core in place in one of my cars for many years with no problems. The vacuum switches in the dash actuate heat and defrost, but there is no dehumidifier in the system for defrost like in an A/C car
 
As I recall from my swap, the mounting holes are all different. The ac firewall also has a hole for the drain that will need to be plugged.
 
Dana67Dart said:
The AC vs heat only use different firewall holes. Probably the firewall is a totally different part.
Click to expand...

It is: as I recall, all Mopar RWD cars from the 60s to M-bodies use a different stamping for A/C and non-A/C firewalls. (The exception may be late A/C-delete C bodies, I'm not sure.)

You could always...cut a piece from anon-A/C parts car and epoxy it over the stock firewall. :wtf: (Yes, I actually saw a Duster where someone did just that!)
 
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