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Installing Classic Auto Air in a '70 Charger

Kern Dog

Life is full of turns. Build your car to handle.
FBBO Gold Member
Local time
10:06 AM
Apr 13, 2012
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Granite Bay CA
I've had this car since March of 2000 and none of the heating nor A/C has ever worked in it. The car was originally an XP model Charger 500 with a 318 2 barrel, 904 automatic, 8 1/4" axle with 2.71 gears and 4 wheel 10" drum brakes. I had plans for a 440 so I kept the 318 totally intact and sold it a few weeks after the 440 was in and running. The car has not had an A/C compressor under the hood since 2001.
I always thought...Air Conditioning is for wimps....Hot rods don't need it.
After a few more birthdays, a few rides in other classics with A/C and several years of driving late model cars in DRY SHIRT comfort in 100 degree weather, I am convinced that A/C makes sense for me.
Some had suggested a rebuild of my stock under dash unit. I don't know much about these except that they are a mix of vacuum and electric in function and weigh a bunch. I had everything under the dash intact...ducts, hoses for the defroster, wiring uncut, everything was there but the vacuum controls worried me a bit. Leaks, low vacuum from a performance cam and the complexity drove me away from sticking with the stock stuff. I knew that I wanted a less cluttered underhood appearance than the original A/C cars had so I looked around at the vendors. Dennis H suggested Classic Auto Air so I checked them out.
I was impressed with the many options they offered for my car. They can build a kit to restore it to completely stock specs for an original A/C car, they can retrofit a "heater only" car to A/C....OR custom fit a series of parts to do a mix of the two.
I ordered the kit in February 2018. Yeah...It has been on the back burner for quite awhile.
One of the things that I wanted at first was to avoid the cluttered look of the stock 4 belt arrangement on the front of the engine. I worked to try to get a 3 belt setup to work, eliminating the idler pulley that the factory used.
This is the way the factory did it in 1970 on big block engines:
AC 6.jpg

For the longest time, this just looked way too busy for me. I started working on the 3 belt arrangement. The main problem I had with that was that I could not find the right single groove water pump pulley. I wasn't alone in that. The other pictures I found online also had the 2 groove WP pulley:

A C pulley 1.jpg

The inner groove would have worked but the outer groove would have just been along for the ride. I tried looking for a WP pulley the right depth and diameter. Mancini, Bouchillon and others that sell pulleys refused to tell me the specific measurements when I told them what I had planned. They only told me the original applications for the pulleys they sell and said they were not interested in selling pulleys that are guaranteed to come back for a refund when they don't fit. Great....What ever happened to hot rodding?
I started looking through my stash of pulleys. I've amassed about 40 or more WP, Crank and idler pulleys so I figured that something out there should be able to work.
I took one apart to see if I could modify it.

A C pulley 6.jpg

Figured I could use the discs to the right as spacers....
It lined up great, but...

A C pulley 4.jpg

There was not enough of the nose on the water pump snout to secure the fan.

A C pulley 5.jpg
A member from Australia posted the following in my thread about my 3 groove pulley idea:

"Hi, I can confirm that the 4 belt is needed to stop belt slip on water pump pulley. I have an A/c car but when i purchased it not connected to a/c. it was running alternator on one groove third on crank pulley ( which works fine). original small front pulley single from crank to water pump to power steering. ( hardly any contact because of the large crank pulley then the positioning of the power steering pulley higher. All day long slips. even with the clutch fan removed and having it done up with so much tension it would almost crush bearings still slips bad. I contemplated a larger diameter pulley for the water pump but then once spaced forward reduces the clutch to radiator distance then you need a smaller ( chev) clutch length.

In my opinion go the tension pulley ( which i believe is only there to take up the belt length slack not aiding in slippage. But because it goes straight back to the crank it has enough surface contact not to slip. the power steer pump runs on the second groove. alternator on the third. and when you choose to install a/c the brackets all allready there you just get longer ac belts for pulley 3 and 4.

My boring opinion. ( your current setup it will be under load looking at the picture clockwise and lift from the water pump pulley. then the power steer will lift the water pump pulley again. causing all sorts of headaches and terrible sounds."

I looked around a bit more and found that this opinion was shared by a few others. I wanted to out-think the factory and make it look simpler, cleaner and lighter but in the end, I admitted that Ma Mopar may have used the 4 belt setup to ensure reliable performance. I went ahead and mocked up the compressor and everything on a spare 440 that sits just a few feet from my car. I sometimes need a mock up like this to wrap my brain around how something will fit.

Mock up 1.jpg
Mock up 2.jpg
This is how the kit shows the compressor to be mounted for a 440 4 barrel: The ports facing up at 11:00 and 1:00 positions. With the compressor sitting on a mock-up and not in the car, it looked to be fine. MORE on that later.
The car had a water pump housing from the mid 70s when they switched the lower hose nipple to the RH/Passenger side. The radiator I had was chosen years ago when A/C was not even a passing thought. The upper hose nipple was on the LH side. This meant replacing the WP housing and radiator.
I got an aluminum WP housing to save weight. A FBBO member made me a great deal on it. "IronBuilt" suggested a Flowkooler water pump so I bought one of those. Another FBBO member spoke highly of the radiators from ECP. I bought one... a 26" unit with 2 rows od 1 1/4" tubes in aluminum with brackets and provisions for a factory shroud.
440 water pump.jpg


I found a nice shroud in the shed...It bolted up with no modifications.
So now the cooling system was sorted out...Then I started a job 107 miles away and time in the shop seemed to stand still for many months. I tinkered a bit here and there but I knew that I needed free time in spades if I was going to dig deep and install this kit.
The job ended a couple of weeks ago and I finally had the time.
I had to take out the console and RH seat to get the massive original HVAC box out.

HVAC A.jpg

This thing is at least twice the size and weight of the Classic Auto Air replacement unit. This has 3 drains, is retained by 5 bolts and 2 straps, has several vacuum pods, lots of vacuum lines and a lot of dust! All the doors and pods move freely though. It probably is a good candidate to be restored. I may keep it for my other Charger I just bought!
The kit has instructions on how to "Bench Test" the HVAC unit prior to installation. You have to connect all of the color coded wire segments to their master ECU, then connect the other ends to their respective ports. Run two wires to a 12V battery and follow the instructions to test. It is all color coded and easy to do. You'd have to be blind or colorblind to make a mistake here. The point of this is to ensure that the air blows out of all the ports as it should. There are two ports for the defroster, two for the face and one for the center of the floor. Mine bench tested fine so the next step was to disconnect the wires from the ecu but leave them on the unit. The unit has the evaporator drain in a different place than the stock unit so a new hole has to be drilled in the firewall. They provide a paper template that is supposed to be placed against the firewall to position the new hole. MINE WAS WRONG ! I followed their template and the hole turned out to be TOO HIGH! This sucked because a hole that was a bit lower would have been okay, as gravity would have actually been a benefit. No...I had a hole 1 1/4" too high and to the side. I had to plug the hole with a bolt and washer after drilling the new hole.
My advice: Mount the HVAC unit and mark the position of the hole for yourself. Putting the unit in and taking it out only takes a couple of minutes. I did it by myself and it was not difficult. THIS will ensure that your drain hole is at least CLOSE to where it needs to be.
It looks pretty messy with wires everywhere.
HVAC B.jpg
HVAC C.jpg
HVAC D.jpg
Wiring is actually VERY simple. You change the fuse on the fuse panel to a 20 amp and run the power feed from the new harness to the HEATER A C spades on the back of the fuse panel. Again, each of the groups of wires are color coded so it all fits blue to blue, yellow to yellow, etc.
It does hang down a little more than the stock setup did.
HVAC F.jpg
Overall, so far it has been laborous but not diffucult. There have been a few snags. The instructions are not as clear as I would prefer. They had no clear location to mount the master junction ( ECU) where all the wires connect. It has two holes to secure it somewhere but you are limited by the length of the wiring. I mounted mine above the glovebox on the back side of the dash frame where the textured black applique is . I made a steel plate, attached the ECU to it, then used the speed nuts that retain the plastic applique to hold it in place. Sorry, I can't find a picture of that though I am sure I took one.
HVAC E.jpg
I left the glove box out in case there is an electrical problem to diagnose. All this time I've left the battery disconnected. I removed the stock ducts, the stock wiring for the heater & A/C, and tagged a few wires that I didn't know about...Key-in buzzer? Uhhh, I don't think so!
The instructions show the routing of all their replacement ducts. I ran them as shown. They replace the center vent with another that looks very close to the original but it has a tapered funnel type port to accomodate the round ducts in the kit. Connecting the ducts was the easiest part of the interior installation but I wished that they included a couple more zip ties since it was easy to pull them too tight if the duct wasn't on properly. If the duct slips off and you try again then the zip ties were not reuseable. I hooked the cigar lighter back up for the first time in several years!
Now onto the engine side.
Keeping in mind that I am new to A/C work, I wanted to mock up the compressor and lines to see if I had everything that I needed. I wanted to be ahead of a problem so that if I needed a different part, I could call them and get it ASAP.
The instructions state to install the condenser first BUT I skipped that to concentrate on the lines and fittings.
So far, their instructions were decent but not 100%. That got worse for the engine side of things. The pictures are drawings, not actual pictures of cars. The drawings are not to scale or accurate. The Compressor in the drawing shows the ports on the compressor in a totally different position and the lines are not depicted in a way that the parts would fit. If I followed the instructions, the ports on the compressor put the hard lines too high, sticking above the hood!
CAA 2.jpg
I may have forgotten to mention that while they DID include instructions in the kit, I LOST them somewhere in my house. I brought them in many months ago to study and prepare but misplaced them. They emailed a PDF but it lists the pages all out of order, many pages and details are missing and because of that, I have had to improvise.
The pictures show the compressor to be mounted upright with the fittings at 11:00 and 1:00 BUT it would not clear the hood......SO I clocked it 90 degrees and wow...The fittings seem to be designed to work this way instead.

CAA 3.jpg

It may be hard to see but the fitting above (With a blue cap on it) gets a hose that runs to the firewall and into the car. The U shaped fitting below runs into a hose that connects to the condenser near the radiator. Fittings are low and clear just fine as if THIS is the intended position. Maybe it is but the instructions that I got were different.
Thats it for tonight. I'm back to it tomorrow....
Nice job Kern. For me, it was a time consuming PITA to add A/C, but worth the effort and tinkering. I added it to my 70 Road Runner and customized the system since I wanted to (mostly) hide the compressor in my air grabber hood compartment. This meant custom hoses and routings.

Keep at the puzzle, and you'll get it eventually! Make sure once you are ready to have the lines crimped that you mark both the hose and the end with a crayon so they will not be twisted or bind. These A/C hoses are pretty stiff and only want to lay one way.

Best of luck!

Well done!! My coronet has Vintage Air and the only thing a car with no A/C can do for me, is take me to one that does. When you move, you'll find that driving in the heat and humidity there absolutely impossible if you don't want to look like you've been swimming with your close on. I've messed with all this before, but not on my coronet, I bought it done. Once you have it clocked and pumbed in, it's not to bad looking considering you added all that crap under the hood. I get the straight and simple look, but for a few horses and a more crowded look, it's worth it!!
Wow, this something I’m going to do this winter. If it’s ok, I’d like to swing by in October to get some pics.
Here is today's update:

The engine side of the installation is proving to have an obstacle at every turn. First up, the drier that is mounted just a few inches off of the firewall comes with a bracket to attach it to the RH fender apron. The trouble is, the hard line dictates the positioning of the drier. The bottom of the drier hits the ridge of the shock tower and the mounting bracket is still too far away from the apron to work:
HVAC N.jpg
HVAC O.jpg
HVAC P.jpg

If the hard line were 1 1/2" shorter, it may have been okay. I had to make a 3/4" spacer to allow the drier can to stand off of the apron and not hit anywhere.
HVAC Q.jpg
HVAC R.jpg
HVAC S.jpg

It is just mocked up here. I had to go out to get longer 1/4 X 1 3/4" bolts to mount it.

Dinner time now. I'll report more in an hour or so.
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One thing the instructions probably forgot to mention... The dryer is supposed to pull any moisture out of the system... Therefore it has a desiccant inside & will pull moisture out of the air... So when I'm doing an A/C I have the vacuum pump hooked up to the system before I uncap the dryer to connect the lines...

Your dryer is now useful for mock up work only... Throw it away and replace it before charging the system....

FWIW I keep a old dryer around so I can do my system mock up & I actually pull a vacuum with the old dryer before I install the new dryer & pull the final vacuum...
Throw it away? I have it capped on the core support end and the other end is connected through the evaporator unit. Do you think there is enough humidity in the air here to ruin it? If so, that is a pisser.
It is not a common size, it is about 2/3 the size of stock ones that I have seen. I can't just grab one at O'Rielley.
Yeah...They never mention anything about that anywhere. The instructions might as well be in Mandarin for as helpful as they are with many things. If a person only followed the instructions, they would have had to call their tech line multiple times, Every aspect so far has required some type of improvised solution.
I'm going to call them tomorrow and try to get a few things straight. This seems almost like a universal kit with a few Mopar-esque parts.

The car has had NON A/C pulleys and brackets on it so I had to switch several things over. The alternator bracket was in the way of the fuel line...so now I get to reroute that. I got the alternator mounted fine. The heater hose nipples I ordered last week: 1/2" and 5/8" turned out to be WRONG for this WP housing. The housing has only 5/8" threads and a 3/4" thread. The old hose nipples I had would have been ok to leave in place. Their instructions show to route one heater hose to the INTAKE MANIFOLD and the other to the water pump. Really? They don't know that a BB Mopar has no water going through the intake?
I pulled the 2 groove crank pulley and installed the 4 groove one. I had to remove the fan shroud to be able to see the bolts to the pulley.
THEN came the biggest obstacle of the day. The A/C pump will NOT fit. The bottom left corner of the compressor hits the thermostat housing.
HVAC W.jpg

The compressor will not go down any lower for the bolt to go through the bracket because the pump hits the thermostat housing bolt.
HVAC X.jpg
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It had me confused. It all fit fine on the other engine. Plenty of clearance there so why does it hit here?
Uhhh....Guess what I discovered.....

HVAC Y.jpg

The old engine has an original iron WP housing and the height from the top of the water pump flange to the thermostat base is just a fuzz over an inch. Call it 1 1/16".

The one in my car is an aluminum housing. Aftermarket. Check out the height difference:

HVAC Y.jpg
HVAC Z.jpg

Yeah....There is the problem. THIS one sits at almost 1 3/4". That is about 5/8" higher, just enough to pose a problem.

So I have a few ways that I can go.
* I can use the iron housing that I used to mock everything up but then I give up the 8 1/2 lb weight savings that this aluminum one provides.
* I could modify the brackets to allow the compressor to sit up enough to clear.
* Maybe someone else has been through this before and made brackets that bolt right in.

I am going to call them tomorrow anyway. I understand that there are always going to be a few small adjustments when working with aftermarket parts. I can't blame them for the compressor not fitting but there is no excuse for the poor instructions and the other problems.
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