Adding A-C to a non A-C Mustang

[RPM 1,107]

Hey guys, I'm wanting to add an original air conditioner to my non A-C car. I've all of the under dash parts, the compressor and its mount. 

 

My question is do I need the original a-c under dash harness, or can the wiring for the a-c be spiced and added to the stock non a-c harness. 

 

One of my issues with buying an original ac harness is the damn cost. Another is having to have the ac harness refurbished and modified for my application, which adds to the cost. 

 

Any advice that agrees with my thinking is appreciated, any advice that will cost me more money will not be appreciated :)

 

Thanks guys. 

[jjstang 49]

I would imagine you could wire it up without a factory harness. 

[Midlife 778]

One wire goes through the firewall grommet, which is a real PITA to add.  You can drill another hole and use a small grommet if needed.

[det0326 168]

I used a non A/C harness and converted to A/C also. As I remember it seems that the blower plug was more to passenger side but I just pulled it back to where I need it and rewrapped it, the old wrapping was not that  good and had to rewrap most of it anyway. The green wire that goes to compressor i used a firewall hole that had a plug in it and just punched a hole through it.  

[Mach1 Driver 502]

If you need a wire diagram its in How Tos, on page 2-E33 

Bob, here it is schematically (also in How Tos):

[RPM 1,107]

8 hours ago, Mach1 Driver said:

If you need a wire diagram its in How Tos, on page 2-E33 

Thanks guys, and especially Mach1 Driver. 

Terry, is it because of you that I've gone original with the air conditioner instead of Vintage Air et al. It's gonna send me to the poor house I tell ya. I'm sure the AC cost will match what I paid for the car in 1989  :)

[Mach1 Driver 502]

Wow! Well I'm happy to spend YOUR money, but how, pray tell, did I do that by just showing you how it hooks-up?

Look at it this way... you probably got a good deal on your car back in 89 because it didn't have AC and you live somewhere near Hades, in SoCal. I know because now I live near what I consider the North Pole in Atlanta. My wife calls me her little California sun beam whenever I complain about the cold.

I hear that a stock AC/heater box isn't cheap, but a Sanden compressor is a lot smoother and quieter than the originals. They have more cylinders and don't chug, chug so much. You can go original on the inside to make it look nice, but go modern up front. A discussion a few months ago on here about the belts and the idler pulley for the AC seemed to indicate that the old York compressors needed the idler pulley just to keep the belt from flapping and newer Sandens don't. That probably isn't an issue with you because you have serpentine now, I believe, but it illustrates the difference in compressors.

[RPM 1,107]

Hahaha... it wasn't this post that convinced  me to get back to using original Henry parts, but one maybe a year or two ago where someone was considering aftermarket air. And I thank you for that way of thinking. 

[aslanefe 310]

@Mach1 Driver Terry,

First a disclaimer, am not an EE guy. Your schematic shows an "AC Mode  Switch" and an A"C De-icing Switch" connected in series. Don't think that is correct.  There is only one SPST switch controlled by a cam on the control panel and it closes the circuit to send power to the compressor clutch either in "Max" or in Fresh" AC modes; so İ think your schematic should show those two switches as "Max A/C" and "Fresh A/C" switches and connected parallel, not series; am İ correct? See these photos for the switch and the cam on the control panel.

[Mach1 Driver 502]

aslanefe, my schematic is only as accurate as the Ford wire diagram that I used to backward engineered it. As I mentioned it is in down in How To's, on page 2-E33. If Henry wasn't right, then the schematic isn't either. It clearly shows a blower switch, AC mode and AC deicing switch. The wire diagram is 30+ pages and I have found obvious errors which I corrected for, but I didn't trace the circuits down component by component. My guess is that it is likely a cost saving revision and the wire diagram wasn't revised.

Looking at your middle picture, I would guess that the maroon two terminal switch is the mode switch, and since it is a single switch it should't be shown as two switches in parallel, but instead it should be more clearly marked as having operating modes of "AC fresh and max". Was there a deicing switch on some other component like the evaporator at one time- who knows? There are a couple of things here that aren't obvious to me- what makes the compressor clutch open and close with temperature? I seem to remember that it cycles with cabin temperature. What does the bottom temperature lever operate- isn't that all tied to vacuum lines? If so, I don't see how it could operate the compressor clutch. Also, modern cars have the AC on with the defroster, but the cam for the mode switch (that maroon guy again) seems to indicate that it is only on in AC max or fresh? When I get to the point where all of mine is working again, I'll have to investigate, unless you can offer some additional insight.

[det0326 168]

There are a couple of things here that aren't obvious to me- what makes the compressor clutch open and close with temperature? 

 

Terry there is a thermocouple tube that goes into the evaporator and it has a switch that is in series with the heater/ac  control lever switch. This is what cycles the compressor on and off with temperature change in the evaporator to keep it from freezing.  I think your drawing is correct. The de-icing switch is the thermocouple switch.  

[RPM 1,107]

Good stuff Dave, thank you. 

[Mach1 Driver 502]

1 hour ago, det0326 said:

Terry there is a thermocouple tube that goes into the evaporator and it has a switch that is in series with the heater/ac  control lever switch. This is what cycles the compressor on and off with temperature change in the evaporator to keep it from freezing.  I think your drawing is correct. The de-icing switch is the thermocouple switch.  

OK thanks Dave, I've been in there once, over ten years ago but don't recall the switch on the evap. Come to think of it, I didn't disconnect the evap as I was after a leaky heater core. Boy that assembly is a PITA. Its like they start with that and build the car around it.

Bob, there is a good video by WCCC you should watch: 

and this at 11:53 sure looks like a capillary tube and switch and just may be the de-icing thermostat/switch:

[aslanefe 310]

Yup, my bad, capillary thermo switch is in series so evaporator does not feeeze.

[aslanefe 310]

I think the AC is on only on 2 AC modes. It is off during  windshield defrost and de-fog modes. Top lever is tied to vacuum control valve (to direct air to floor, dash etc) and also activates the AC switch; bottom lever is tied to blend door cable which diverts air through AC evaporator or heater coil (or mix of both) to adjust the output air temp.

[RPM 1,107]

Thanks guys. Terry your not the first to think Ford built the Mustang around the heater box. I've watched a ton of WCCC videos because they're so well done, but didn't think to look there. I'll give them a watch. 

Thanks again. 

[RPM 1,107]

Is this hole the correct location in the toe board for the drain tube?

 

[aslanefe 310]

3 hours ago, RPM said:

Is this hole the correct location in the toe board for the drain tube?

 

 

Yes.

[RPM 1,107]

Thanks John. 

[det0326 168]

How is the drain nipple on the heater/ac box? Had to repair/make one for mine. Most are cracked if not broke off.

[RPM 1,107]

Ya, it's pretty close to a pristine box. 

[RPM 1,107]

On 2/2/2022 at 10:07 AM, Mach1 Driver said:

If you need a wire diagram its in How Tos, on page 2-E33 

Bob, here it is schematically (also in How Tos):

Hey Terry, for whatever reason, maybe loft, I'm not able to find the wire diagram on page 2-E33. Would you be so kind as to post it here please?

Thanks. 

[Mach1 Driver 502]

Its kinda hard to read, so included the link to the How To's section first: 

[RPM 1,107]

Thanks bro.

[stangs-R-me 109]

Before you install your "pristine case" in the car, you should add a brass tube support ferrule glued inside the fiberglass nipple as I did on mine.

The nipple on my original and spare case were both broken off and I was looking for a way to repair and came up with this idea and it worked great. 

The brass tube support ferrule O.D. is the I.D. of the fiberglass nipple and was about the same length.   Found at the hardware store ... IIRC its function is for use on soft tubing / hose inside a tube nut.

See pics