Adding Ac


Mustang Master
Mar 29, 2020
Idle hands can be dangerous to the old checking account. I have some free time so I am plotting my next step.

I am going to install ac into Christine. I have some other issues to contend with first but wanted to get started on the parts as well as info collection process. My intent is for it to appear stock on the inside. Under hood I do not care about stock. I want the best performance from the system for my dollars.

I have a 76 cobra as a part car but all the under hood items are long gone. The ambient temp sensor is even missing. The heater box and controls are still there and will be cleaned up, refurbished and installed into Christine. I am going from a 76 to a 78 so some wiring will need changed.

Since I am starting fresh under the hood I am thinking of using a sanden compressor. They are lighter and more compact vs the old york. The downsides are the performance at idle is not nearly as good as the york and mounting it may become a pain in the ass. Looks like I will be making brackets as the ones I have found so far, use an adapter along with the heavy york brackets, have the compressor sitting way too high or not compatible with power steering. The ones that claim to work are $800 to $1500 for a kit. I will not pay that kind of insane markup for some brackets and pulleys.

I did find the ac heater core at Rock auto as well as a blower motor so I just ordered them. Looks like the heater core is no longer in production. Everyone but Rock listed them as out of stock.

I found a company called auto ac solutions who make an evaporator for 77/78's. The connections at the firewall appear different for 74/76. Since I am starting new I will need lines made up anyway. So it's not an issue. I am hoping the rest of the evaporator is the same between the years.

So far the only piece of unobtainium I have found is the blower motor resistor. I will test the one there and hope it works. They are fairly easy to replace once installed anyway. If it needs replaced I will get measurements and see whats closest in size and make it fit. Other then a connector it should be fairly easy to make an adapter plate for just about any 4 speed resistor.

I also found a new condensor for II's on ebay. Once I get further along I will order it.

It will probably take me until next spring to get it operational. So any input is appreciated.
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Does anyone have a II equipped with ac and rear defrost? Can I get a picture of the control unit?

I have one labeled D6ZH-18532-AA. It looks the same dimensions wise but has red and blue markings, a lot of chrome trim and a shiny surface. All the II panels I have seen are just matte black with white lettering. Searching this part number brings up several iterations. Looks like Ford used the chassis of the assembly and never updated the part numbers for the different faces or configurations. I have not found an ac with rear defrost from a II yet.
I used to have a car with both AC and rear defrost. It looked just like the other models without rear defrost, it just had the defrost switch to the right. It was an identical setup to my current control panel in my car without AC and with rear defrost. I can't help with any pics of the connections or anything though.... :shrug:
This is identical to the one in my car now, pic courtesy Ebay :


Imagine the one below with a rear defrost switch just like the pic above - that's what it looked like. Unfortunately I can't find a pic of one anywhere. :shrug:

Of the parts cars sitting here none have both ac and defrost. I grabbed this off ebay a few years ago but never looked closely at it. According to the part number it's for a 76 mustang hvac. Searching this number brings up trucks, lincolns and granadas as recipients. yet they are all different. Some have switches on the bottom. Some have ac, some defrost. I cannot find one yet that has ac and defrost as well as looking correct. Ford used this number for several years and models yet kept even the suffix the same.

I have a non ac rear defrost panel in the car now. Just like that ebay one. I have an ac one without defrost. Or this one which looks like it will fit but won't look right. Maybe it will look okay. I wanted the interior to appear stock. It's a minor thing but....

I am going to keep an eye out for the correct one but will use this one for now. That way I can just swap in the correct one once located.
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I'd say if you can get that one to work there wouldn't be many people wise to the difference. Honestly, I think it might look better than an original piece.
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I forgot to check the Mach I. It is the correct piece. Defrost and ac. I wont steal from it though.

Looking at the car it started as a base model and was sparse inside. I have added the ac dash pieces and clock. The console. The stereo has more chrome then I would have liked but pairing it with this control panel may actually look good. So thats the current plan. Run with it and see what it looks like. As you say it may look better then the original piece and mesh well with the other things I have added.

Now to figure out pulleys. What a pain. Ford used several different setups there as well.
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I am very interested in all this, as I want to make the ac work in our Cobra.
Was eyeballing the retro kit for the early Broncos but spendy and would need different lines.
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I talked with the local shop. He is going to make the lines once I get as much as i can get done. Lines shouldn't really be a problem for any good shop. The caveat here is 77/78 have standard evap fittings where the 76 and earlier uses the funky manifold at the firewall. The replacement evap is the 77/78 style and I believe fits in the 76 and earlier case. We will soon find out.

Ebay has a condensor for us. Cooling will be another issue for me but we can cross that bridge when we get to it. Currently running a 16' electric fan and an oem radiator of unsure vintage.

One problem I am having is deciding what compressor and how to mount it. I have a york setup in the parts bin. It's heavy. It's power hungry. Loud. Doesn't like high rpm. But it produces well at idle. It will need rebuilt or replaced but I have the huge brackets.

On the other hand. The a/c system will be new and r12 is expensive. R134 makes the most sense for future proofing. So do I go with the more efficient and more importantly much lighter sanden setup. The peanut is small enough to fit in stock location. It puts out almost half the York at idle though. Considering my evap is stock will it work well at idle? Does it flow enough to function at idle?
I don't know if I'm an expert, but I've seen a good number of pulleys and had to go through a process to find what worked for my car. It's not all that difficult with V belts really, just have to make sure they're in line. The same would hold true for a serpentine belt - which leads me to this question: if you go with a newer style compressor, will you be going with some kind of serpentine setup? I'd think that that would make finding a newer compressor much easier if you decided to go that route.
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First time with power in a few days. We were hit with a tornado and it tore half the roof off my barn/workshop. I have...well had a huge maple next to the barn which decided to shed the majority of itself onto the barn. It damaged the rest of the roof and crushed the back corner of it. Alot of my tools and my toolboxes are soaked. I had interior parts stored in the loft that were soaked. The cars are fine except my sons II had the hood torn off and flew about 50 feet. My car was drenched and had water inside as the t top seals are not really seals anymore. The 5.0 I was going to put in the coupe is filled with water. Be a while before I get back to car stuff I would think. My pool, chicken coupe, and house siding all have damage. Barn took most of it though. I have multiple large trees that are down. My favorite tree was a big cedar and it uprooted.

On the plus side we are all safe and our town only has a couple injuries. No fatalities.

I have a new blower motor and heater core on my kitchen table. Evap core should be here in a couple days. Before the storm hit I jumped the old blower resistor and it works as it should. The blower works but makes a lot of noise. Amazing to me a 1976 with 110,000 miles and it works. My 03 Durango went through them like I do coffee. I replaced the wiring and connector a couple times as well.

I am still trying to decide on belt/pulley options. The Sanden compressors are readily available with a v belt clutch setup as well as the serpentine belt. All the aftermarket brackets I have found require the stock ac platform/bracket or a different power steering pump. None fit the plastic/aluminum pump the 78's have. I am trying to keep weight down so I want to avoid the stock bracket is possible.

My Coupe has a 1989 grand marquis 5.0 including the front dress. It fits well in the coupe. Only a couple issues. One is the ac lines come out the top of the factory grand marquis compressor and they wont fit. The compressor clears but the lines would hit the hood if they are installed. Other is the water pump has a larger lower hose outlet. I just used a grand marquis lower hose and cut it to fit the II radiator. Kinda jankey but I can find the right water pump. May be able to reuse the current one. It also moves the compressor to the passenger side and alternator to drivers side. Not a big deal for me as I am not worried about stock under the hood. I am using a 1 wire alternator and will need ac lines made so location is not really important if everything fits on my build.

Finding another 89 marquis front dress would be the best option in my mind currently. This would give me a serpentine system and maintain the clockwise water pump. From my understanding all the other serpentine system require reverse rotation water pump. They should have a different timing cover which is hard to find with a mechanical fuel pump setup. Using a Sanden peanut compressor would fix the clearance issue as you can rotate them almost 90 degrees. The downside is I am not sure the factory evap will work well at idle with the lower output of the peanut. It should be fine at higher rpm's though.
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Good to hear everyone is ok! Sorry about the property though. Hopefully insurance will help take care of the majority - if not all - of the property damage. Water damage, on the other hand, sucks! I hope nothing of value was ruined.
Progress is basically at a stand still. Has taken over a month but we finally received the insurance check. Now I can order the materials as soon as the check is cleared. Then get a roof back on the barn. Then I can go back to playing cars.

I cheated while the boss was away and pulled the heater box out of the old cobra. I did not have to pull the whole dash. I pulled the right side loose and the bar in the center. I removed the ducting and radio. That was enough room to get the box out. It was tight and probably would have broken some plastic on a cold day. On a warm day there was just enough flex to get it out. I will have to have help or take more of the dash loose to reinstall it into Christine. I didn't care if something broke on the old cobra but do not want to break Christine.

My god this thing is heavy as well as huge. It's gotta be the 3rd biggest item on the car. Engine, trans. heater box. I have done this before but I swear it was lighter 30 years ago. So either my memory is fading or my body is failing. Hmmm. Prolly both. If I had the money I would seriously consider getting a new heater box from vintage air or the like. They would be hard to mount but if one fits it would be smaller and has to weigh less.

Tested the vacuum actuators and they perform as intended. I will probably regret it but I am not replacing them. Someone had this box out previously and broke some pieces of it. The blower had 3 different sized bolts in it and has about 1/4 of the mounting surface broken off. The metal piece that connects the fresh air plastic duct to the heater box is half rotted away. I will treat the rust and get something that stays flexible that can stick to metal and plastic. I used to do heating and air rough-ins and we used thumb gum to seal the lines when they penetrated the house. I know it has other names, dum dum tape being one. Something like that is what I have in mind currently. I will get some type of epoxy to repair the broken bits. The pieces are there so it's a matter of picking something that sticks well to this fiberglass looking plastic the box is made of.

I received the condenser yesterday. It's still in the box but that's the last II specific piece I needed. Other then the correct blower motor. I ordered one but it's not the right one. That can be done at anytime though so not holding anything up. Next items are picking a compressor and deciding which front dress to use.
You should be definitely be looking for a good used HVAC case with factory A/C
Use whatever compressor that floats your boat
Do not use a kit with hose clamps on the hoses
Have your hoses custom built if you cannot find (or do not want) a York setup
You can convert all those old ones to R134a with ester oil
Buy the control on ebay
How the hell did you get a picture of my car from the future? What year do I finally get it painted? The king air damn does look awesome on it. Do you know when I was able to afford the blower? Nevermind. I don't wanna know. Some things are better left alone.
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