Factory ac questions
 

So ive got a 69 lemans that was a non-ac car that im installing the factory ac system in and have a few questions. Ive got a few templates for cutting the firewall but still have a few questions. On the underdash box, there two holes and the top and bottom that have holes but no bolts. From the looks of it these holes would be inside of the firewall case so i cant imagine there should be bolts there. Maybe some kind of alignment pins? Anyone know what the holes are for? ( see the attached pic. Holes are circled.) Second question is can someone take a measurement before the top of the firewall box and the lip of the cowl so i know if my marks put the box in the right place (see the other attached pic of when i need the measurement. ) thanks for your help guys!

I'll try to get some measurements and pics tonight.

Thank you! I appreciate it.

Since you’re adding ac to a non ac car, I assume originality isn’t your first priority. (Assuming only, not judging)
I have a factory ac 71 firebird that I did a resto mod and painstakingly reconditioned the factory ac and it was the biggest mistake of my project. This spring, ripping it all out and putting in an aftermarket system. Not even a close decision.
My 2cents

Yea, i added a 72 AC system (complete. & working) into my 68 GTO non-AC 4- Speed car. Cut the firewall per 72 template, and hooked itall up nice.

Never charged it. Took the compressor off. Now Kinda looks like my 1st GTO underhood.

Definitely not worried about orgninalality. Its technically a lemans that will be cloned into a gto and ill be resto moding it. One of the big factors for going wirh the original system is i got a complete working system for 100 bucks. Hard to pass on that. I also worked at a classic car dealership for several years so ive delt with both the original system and even installed several aftermarket ones. I can say, if done right, with a few modifications/changes and charged with r12 the original systems will always blow colder then any aftermarket system ive ever delt with. They can definitely be a bit finicky compared to the new systems and the plan was to go aftermarket until i came across this set up and for the price, i couldn't pass it up. Out of curiosity, what didn't you like about the original system.

Big bulky, ugly. Ductwork fragile and leaky no matter how I tried to keep it together. Vacuum operated controls and mixing doors vs lower vacuum signal. Just a jenky system and on a good day worked like garbage. Imho just outdated technology that may have been cold, but distribution and mixing always sucked.

Here are a few pics from a project that I started back in 2011, 68 LeMans. Had the Evaporator flushed, acid washed, leak checked, Compressor rebuilt and installed new a Hearer Core and that's as far as it progressed.



it appears that the red circled holes in your pic are for larger sheet metal screws.
Let me know it you need any other details.




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Dave

I cut mine the simple way. I had to strip my fiber glass shell anyway so I put empty shell on firewall . Blower motor hole mounts perfect. Than mark &drill mounting holes . Slide in inside box . That gives you hole to cut & were to wield patches

Blower motors were too weak, and drew high Amps. I sought the most capable used blower motor and was pleased with defrost and floor, but vents were as-you-said weak.

95 Lincoln towncar vents/defrost/floor are fantastic and quiet. Give me an idea on grafting that blower motor.

Yeah, I’m sure for some it’s optimal but for me I spent a lot of money on new condenser, new evaporator, new blower, lines, compressor poa update and meh.
Like I said, all comes out this spring and starting new w vintage air.
Good luck either way!

Here are a few pics of an installed jacket. Space between the underside of the firewall lip and top of the jacket is 0.4”.

However, in your situation I would simply mount the jacket reusing the bolt holes around the blower portion of the firewall [tucked in to the fender area] and then placed the jacket on the firewall and tweak it so that it looks nice and level and then mark the holes you’ll need in the area behind the passenger cylinder head.

As for the Relative ability of a factory AC system all I can say is I’ve driven these cars for 40 years and a properly functioning factory 60s GM Air conditioning system filled with R12 keeps the car wonderfully cool in any weather. Most complaints about fan speed typically are actually a problem caused by 50 years worth of gunk blocking the heater core and or the evaporator Thereby restricting airflow.

Thank you dmorg1 and north for the pictures. Thats exactly what i was needling.

This is my firewall a 70 gto heater car it's not that complicated. Um going fac. A/c also . The heater hoses , its just a elongated hole

I did the conversion back in the 90’s to a judge I was daily driving. One issue is the air inlets on non AC cars that feed the upper dash vents. They interfere with the AC ducting to those dash vents. You’ll have to chop them off and seal the holes from the plenum well because that’s a high pressure zone so rain while driving will end up in car.

Good to know now .I'll save a little head scratching. Any other suprising thing to consider? Tks for tip.

Depending how thorough you want to be AC GTO’s had…

4 core rad instead of 3

7 blade clutch fan instead of 5 blade flex

Different crank and water pump pulleys

seals around the frame at the rad support

Air dam under rad support

55 amp alternator instead of 37

3.23 diff instead of 3.55

Ambient air sensor on passenger side top of rad support

Extra vacuum fitting of carb for AC control head

Jumper harness to bring power direct from alternator to compressor and high speed fan

Extra dash vent on center of pad

Cover plate and specific kick panel on left side

Fresh air intake valve and specific kick panel right side

Heater core is specific to AC

Firewall has specific hole for AC vacuum supply

Are you switching dash pads to have the center vent?

I concur.......the stock A/C on my 69 has been freezing me out of the car for 50 years

Tks I've been collecting parts for several years but ambient sensor on rad. ? I know about firewall one. I'll have to look at my reference books again. Um not going 100% stock but want the look (new rad, sniper fuel ,compressor ,its father & son project..tks so much

Sorry, I meant to say the one on the trop of the firewall near the jacket

Ok , feel better now, it's not to easy to find tks

Yeah your both right. Forget my original post. The ac is the best thing I ever added to my 71. To the op. Go for it. Spend 3000 bucks converting to old technology. Thanks for correcting my opinion.

AC still worked fine on my 68 GTO when I bought it in 1976 with 90k miles on it. Plan on refreshing the OEM system, will use R12 if I can, new blower motor, rebuilt compressor. Evaporator looks almost new, will have the condenser tested, vacuum tested all the diaphragms, cleaned all the switches ... so far so good.

My only complaint about the OEM system is the compressor ... seems a bit much, I'll look into something newer if there is anything compatible with the old system.

I would agree with your post.
For the record, it wasn’t directed at you I must have “quoted” the wrong guy. Kudos to all the guys with a car that came with factory ac and it’s so cold there are penguins in the globe box. Go you!!!! Yours didn’t come with ac and mine isn’t where I wanted it to be given the investment.
That said it was a dickish response nevertheless so just ignore it.

I added a complete factory A/C system to my '68 GTO nearly 30 years ago. I was able to use the firewall from the donor car. I cut out the necessary area and then welded it into my car after removing the non-A/C firewall piece.

With regards to the interior A/C box, the holes are for alignment pins. That box attaches under the dash and mates up with the heater-A/C box that houses the blend doors. There is a square gasket that is sandwiched between the box attached to the interior firewall and the color matched box that directs air to the A/C vents in the dash pad.

It is a very formidable job that will require making cuts in the metal part of the dash at the far ends of the dash on each side.

Not an easy job, but it can be done. Remember, R-12 is not available in the USA, but can be imported from our good friends in China at a very high cost. You may want to look into finding a compressor that works with R132a. It will not look original, but are you interested in what it looks like, or being cold in the summer?
Be prepared to see a drop in MPG, but going form 15 MPG to 12 or 10 is probably not that big of a deal. Good LucK!

Ambient sensor is supposed to go on the passenger side above the firewall. Never heard of it going near the radiator.

You apparently haven't looked very hard for R-12 lately. It's fairly readily available with all the cans that were hoarded back in the 90's and before. Check out ebay. I found lots of original cans there. Just make sure you don't buy "R12 replacement" or R12a or some other nonsense like that. Make sure it's genuine R12.
https://www.ebay.com/itm/125125587683
https://www.ebay.com/itm/325032281325

The original A6 will work fine for R-134a. You just have to drain out the mineral oil and replace with PAG150 or whatever the correct viscosity of PAG is for this compressor.

hgerhardt .... if a person buys a new A6 will it come with PAG type oil? I see them being sold brand new these days. Also rebuilt.

How critical is it to clean out every last drop of mineral oil from the various other components? I mean is like a teaspoon of mineral oil total going to cause harm?

While I've never actually done this mod (my '66 GTO is still R-12), I've read that a bit of residual mineral oil is no problem as it settles out in the lowest point and stays there. Mineral oil won't mix with R-134a.

And as for a new/rebuilt A6, I'm not sure what oil it comes with, so better to ask the manufacturer, but probably nowadays it would be PAG... which means if you are going to use a new/rebuilt A6 in an R-12 system, better drain it and replace with mineral oil.

Hoping to use R12, I know a guy with a horde :) But just wanted to know what the options are. Up in the air whether or not to try using the original A6 I have from a 56K mile car. Seems to be in pretty good shape, and not sure if I want to learn how to rebuild an AC compressor.