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 R134a conversion, '73 Firebird
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Lee
Sitting Bull

126 Posts

Posted - 21 Dec 2017 :  12:53:43 AM  Show Profile  Visit Lee's Homepage  Reply with Quote
Per Phil's request for more info on my conversion.

GM's A/C systems changed and evolved every few years, through the 70's. As such, what worked on my '73 will not all be directly applicable to car a few years newer. Due diligence is needed, to determine what parts are required for your vehicle.

My conversion was greatly helped by Ron Mineo, at ClassicAutoAir.com ( ron@classicautoair.com )

When I got my '73 T/A clone a couple years ago, the original A/C was complete, but not working. Included with the car was a POA valve calibrated for R134a refrigerant. [NOTE: a few years later GM stopped using POA's, and started using orifice tubes]. I already had a Sanden compressor and Pontiac brackets, which I had obtained in a trade several years before but never used.

The Sanden compressor is what comes with most retrofit A/C kits. It is MUCH smaller and lighter than the original compressors, and uses less HP to operate. The brackets I have mount the Sanden so that the pulleys are in the same location as the original compressor. To make the compressor a bit less obvious, I painted it with low-glass black paint, along with the brackets.

cont.

CURRENT: '73 T/A clone, boring at the moment...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
www.LNLPD.com

Lee
Sitting Bull

126 Posts

Posted - 21 Dec 2017 :  01:15:00 AM  Show Profile  Visit Lee's Homepage  Reply with Quote
I contacted Ron, and he was quite helpful. He had a kit that had most everything I needed, actually it had more since I did not need the POA or the compressor/brackets. The POA I had was from a different company, but Ron was confident that it would work fine.

One thing he STRONGLY urged me to do, however, was to pull the original evaporator and have it pressure tested then flushed. I pulled it, along with the entire "suitcase" off of the firewall, which required me to loosen the fender and pull the fenderwell. I took the evaporator to a local radiator shop, and they actually pressure tested it for me for free! It was good to go.

There are some expensive "flush kits" you can buy for flushing the evaporator. But Ron gave me clear directions on how HE does it. It's been well over a year now, so do your own research - but I believe it was mineral spirits he told me to buy. I poured some in, sloshed it around, then blew it out with compressed air - repeating multiple times. This is to remove the oil used in the original system, which is TOTALLY incompatible with the R134a. The evaporator is the only original part of the refrigerant system that I reused.

I pulled the blower motor while I was in this far, and cleaned it up. It was working well, so I reused it. I had to go to a "hub" O'Reilleys to find it (most of their stores didn't know what the heck I was talking about) but bought "caulk rope" (black, sticky strips) to properly reseal the blower motor and the evaporator suitcase. If you don't do this, you'll be blowing cold air out all the seams, instead of into the car.

The original condenser is an "S" type, making multiple bends before heading to the evaporator. For R134a, a "parallel flow" condenser is recommended, and was supplied by Classic Auto Air, along with mounting brackets made specific for the Firebird. The condenser and brackets assembled nicely and installed with no issues. The new drier mounted with the condenser, with a hard line to connect it.

With the evaporator flushed, tested and reinstalled; the evaporator and drier installed; and the compressor and brackets installed; the next task was to connect them all. Ron provided me with the proper hoses and connectors, but with so many variables about the compressor location and such, the hoses only had one end crimped on. I had to test fit everything, in order to determine hose length and proper clocking of the fittings.

I used wide masking tape to wrap around the hoses and fittings, where the cuts and connections needed to be made. I marked cut lines on the hoses, then made a "clock" line on the hose with a corresponding line on the fitting. I then took the hoses to a local hose shop, where they cut the lines, matched up the clock marks, then professionally crimped the fittings to the hoses.

While at the shop, I also bought industrial high-temp high-pressure hose to use for my heater hoses. These should last for decades, and I think I paid maybe $40 for them.

cont.

CURRENT: '73 T/A clone, boring at the moment...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
www.LNLPD.com

Edited by - Lee on 21 Dec 2017 01:19:32 AM
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Lee
Sitting Bull

126 Posts

Posted - 21 Dec 2017 :  01:33:03 AM  Show Profile  Visit Lee's Homepage  Reply with Quote
You have to lubricate all the fitting O-rings, but the lubricant is included with the C.A.A. kit. Install all the lines, and you'll need some pretty big wrenches! I'm pretty sure I used a 1" wrench, and think I needed either a 1-1/16" or 1-1/8" as well, along with several smaller sizes. The connections need to be TIGHT and leak free, so you have to crank fairly hard on most of these.

Once it was all connected, I connected a vacuum pump and pulled vacuum. There are all sorts of websites with current info on pulling vacuum, and how to actually charge the system, so I won't bother with that. But you can get a decent vacuum pump and R134a gauges at Harbor Freight for a lot less than I expected!

Initially, I was not all that happy with my system. It just did not seem to blow as hard as I had expected (or as hard as some VintageAir systems I had installed). After some troubleshooting, however, I discovered the trap door for the "recirculation" (located in the cowl, passenger side) was not closing. Turned out that there is a vacuum diaphragm that closes the door, and mine was busted. I could not find that part new, but finally located a good used one. With that installed, the door closed properly and air flow increased dramatically!

I've also gone through and resealed much of the interior duct work, as most of it was poorly sealed after all these years. No, it is NOT as cold as my wife's Lexus. But I've been out on sunny Texas summer days where the temps were in the upper 90's, and I was comfortable in the car.

One added bonus is I have very good access to the #2 spark plug. The much shorter and smaller compressor does not cover it up like the old Frigidaire did.

CURRENT: '73 T/A clone, boring at the moment...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
www.LNLPD.com
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Bill Boyle
Horse Feathers (Charter Member)

USA
4869 Posts

Posted - 21 Dec 2017 :  04:49:30 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Invaluable information on the Classic Auto Air R134A conversion for the '73 Bird.

Bill

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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