Air Conditioning: Factory vs Aftermarket - Pontiac GTO Forum
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post #1 of 12 (permalink) Old 03-26-2016, 11:00 PM Thread Starter
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Air Conditioning: Factory vs Aftermarket

I have a 72 LeMans that I am working on making a daily driver and cruiser. It's a factory A/C car, but some years back I tossed the last pieces of the factory system that were under the hood thinking I was doing myself a favor (I installed an ac delete panel from OPGI). I now think this was a big mistake.

Since there is no direct conversion kit from any aftermarket company for this car, am I better trying to force an aftermarket unit, or trying to piece back together the factory stuff while converting to r134a? A look through eBay puts me around $1000-$1500 for parts to piece the factory system back together with the r134a upgrade. Which system will be likely to work the best?
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post #2 of 12 (permalink) Old 03-27-2016, 05:19 AM
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The aftermarket systems will "work" doubt there. The cost, if you do it yourself will probably be about the same either way. The question in my mind is how important is originality to you? I love the way my Vintage Air system performs in my 64 but I wish I had factory vents. You probably don't have that issue if your car came with AC.
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post #3 of 12 (permalink) Old 03-27-2016, 10:44 AM
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Originally Posted by Koppster View Post
The aftermarket systems will "work" doubt there.
My personal experience is different. The performance of my aftermarket system is vastly inferior to that of my original factory system. Even though I still have all the parts to my original system, I chose to go aftermarket for several reasons:
1) Through ignorance, when I removed my original system during disassembly, preparing to restore the car, I left all the components open to the atmosphere. Much later, I found out this was a no-no and probably ruined all the pieces - which would probably need to be replaced ($$$$) including the POA valve which is near impossible to find.
2) I built a fairly stout engine for the car and was concerned about having sufficient idle vacuum to operate the factory system.
3) I was concerned about being able to get R12 to charge the factory system, and research led me to the conclusion that converting an R12 system to R138a results in a much reduced cooling performance.

So, I went with an all-electric aftermarket system. No one made a plug-and-play system for my 69 GTO at the time (and perhaps still doesn't), so after completely striking out with Vintage (they were pretty dismissive and seemed to not even want to talk to me), I found a local supplier who was willing to try to help me assemble a custom system.

I was successful in that regard. My aftermarket system LOOKS factory, uses the factory vents, and the factory controls. I even managed to get 4-fan blower speeds out of it even though the system "really" only has 3 speeds, though some creative electronic hacking (I now have a "super" low speed that is below the unit's originally lowest speed.)

However, there are things about the aftermarket system that I didn't realize at the time, namely:
1) The unit operates in "recirculate" mode all the time. You lose both the 'vent' and 'outside air' modes of the factory system.
2) The air-movement capacity of the blower motor is just plain wimpy. Even on the highest speed, the volume of air it moves is roughly equivalent of "low-medium", maybe even "low" on the factory system. As a result, on a hot Texas day it can't keep the interior of the car cool. The best you can hope for is almost-but-not-quite tolerable. --- And this is even with the lap vents from the factory system not installed at all. I completely blocked off one of the air outlets on the aftermarket unit and am only driving air out of the three upper dash vents because I couldn't figure out a good way to connect the lap vents to the system - so you'd think this would cause it to push more air out of those three --- but it just doesn't.

So... one of these days when I get my new shop all fixed up and have the time to do it, I'm going to be pulling the motor to re-do the rear main anyway. At that time it's going to be tempting to revisit my a/c decision. Something's got to give - either I've got to find another blower motor with enough butt to move some air, find the as-of-yet undiscovered reason it doesn't, or give serious consideration to repairing and re-installing my original R12 system. I've since learned it's POSSIBLE to get R12 still, you just have to jump through a lot of hoops (exams, certification) to be able to buy it and it's very expensive.

As usual, your mileage may vary - everyone should make their own decisions, past results are not an indication of future performance, void where prohibited by law, etc.

This has just been my personal experience.


Springtown, TEXAS
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post #4 of 12 (permalink) Old 03-27-2016, 08:31 PM Thread Starter
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Bear and Koppster, thank you for your insights on this issue. Bear, I'd seen some of your thoughts on this in other posts, I appreciate the full write up of the issues you've had all in one place.

Much like you, I tossed the box and evaporator thinking I would be going aftermarket down the road. I made the decision partially because the fan didn't blow very strong even on high. I thought it was a flaw of an older system as compared to modern cars. I found the inlet side of the evap covered in dust, hair, leaves, etc which is the most likely culprit for the weak blower since it blows fine now without the a/c parts on the car. But between lack of a direct aftermarket solution and recirc only on all aftermarket options, I think tossing what was left was a mistake.

Looks like I can find a used replacement box and evap for ~$200, or refurbished ~$500. And the compressor, condenser and hoses for $600-800. So the total price will be in the ballpark of an aftermarket unit. I don't care about originality much at all, but I am very concerned with functionality and want to use r134a for cost and convenience. The controls and the inside portion of the hvac stuff is still there, so I think I'll have to go through that portion of it as well as restore the wiring. I've got electric fans and an aluminum radiator that keep the car very cool even on a hot summer day, so I'm not worried about the added heat load of a/c on the radiator either.

From other research I've done it looks like having an upgraded condenser and Sanden compressor will make the r134a work fine with the stock evap. This isn't much of an issue because I'd need the condenser and compressor anyways. They were already gone when I bought the car, along with the hoses.
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post #5 of 12 (permalink) Old 03-27-2016, 08:56 PM
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I am in Ca. and can get R12 through a source codename for R12 is hot paint.
The hardest part of my A/C restore was sourcing another plenum, some hack took tin snips to the core support so he could remove the heater core from the inside.

Both of the fiberglass plenums were brittle from age and I had to fabricate the broken ears for the doors and use fiberglass cloth and resin to re glass it to make it structurally sound since nobody remakes this part.
I also had to rebuild the control and I used a vacuum pump to bench test it and get the hoses marked and in the proper spots.
The vac can on the engine side was a single port someone along the line moused in and I was able to get the proper dual port from Ames.
The way the hoses were when I bought it none of the doors worked properly and the heater was blowing at the same time the A/C was on so even though it was recharged and working I had no cold air.
It works great now, I have to shut it off idling in traffic or coming up the mountain but no problems with it at highway speeds.
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post #6 of 12 (permalink) Old 03-29-2016, 05:05 PM
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From what I've seen, and friends I know who have '64 and '65's, the Vintage Air system outperforms the original AC in their cars. One original owner said his '65 originally cooled ok up to about a 90-95 degree day, but not if it was 100 degrees or hotter out. He said the Vintage Air keeps him comfy even when it's 110 out, and in Fresno, that is a reality during the summer. Another friend has it in his '65 Chevelle, and it will flat freeze you out of the car. That said, not sure about the newer A body cars, like yours and Bears, that have no dedicated aftermarket system available. I have personally done a few R-134 conversions to these type of vehicles with the old fashioned R12 systems and the big GM compressors, and have had no issues with any of them. I did not change hoses or any of that nonsense.....just a new receiver/dryer, pull vacuum, add oil, and fill with a 75% charge of 134. These systems worked very well converted, and have held up over time. If I had a factory air '68-'72 A-body, I would probably run the OEM system with 134 in it. Sorry to hear about your lackluster results, Bear, after all the hard work and $$$ you put into it. Neither of my GTO's ever came with air, but I have been toying with a Vintage Air system in my '67 ragtop for awhile gets HOT where I live!
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post #7 of 12 (permalink) Old 04-01-2016, 09:20 AM
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Vintage Air makes a system for the 67 GTO...I put one in works very well...I THINK, custom air or perhaps VintageAir now has a system for 69 GTO....
What BEAR says is TRUE...the system only works on recirculated air....which is all I ever used anyway....equal to the "MAX" setting on most cars....

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post #8 of 12 (permalink) Old 11-19-2017, 11:15 PM Thread Starter
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Been a while since I revisited this thread, but I did decide to go factory based largely on the feedback here.

I found a restored box with POA valve calibrated for R134 online, it's sitting in my basement now waiting for me to piece the rest together and then install it.

The only unknown for me right now is whether the controls in the car will work properly. I'm pretty confident in needing to remove the dash to get this working, so I may have to wait a while longer.
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post #9 of 12 (permalink) Old 11-20-2017, 09:13 AM
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A stock factory '68-72 A-body/ 69-72 GP AC system will freeze you out. I've had several that all that was needed was a new drier & recharge. Have always used r12, have a good supply, & never had problem getting more. My experiences with 134 conversions has not been as good, but most of those vehicles were early SUV's & GM pickups with a lot of window exposure with minimal UV & heat rejection. Have reinstalled, as well as shipped out dozens of clean original AC control heads with cables attached, most from 100-150K mile parts cars, & just have not ran across feedback of problems with them. Compressor mtg parts wise, most of the 71 & 72 AC bracket pieces interchange with same parts from traditional Pontiac engines installed up through the late '70's.
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post #10 of 12 (permalink) Old 11-20-2017, 01:44 PM Thread Starter
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The only pieces still with the car when I bought it were the evaporator and fiberglass box under the hood, everything else was missing. In my infinite wisdom, several years ago I tossed the box and evaporator thinking they were junk and I would use aftermarket AC.

Since I'm starting from essentially scratch, I figured I'd go with R134a for price and availability. Others on here and elsewhere have converted without issue, so I'm looking to do the same.
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