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I went through several old threads on the subject but would like current opinions.
I have most of the used parts for a/c install on my 70 cutlass convertible.
I am wondering if it make sense/cost-effective to get appropriate parts tested and update the connectors to use r134 (radiator guy said he can test).
The other option I was looking at was not cheap. https://www.originalair.com/68-72-cu...t-134a-stage-3
Thoughts?
Might depend upon where you live. In a very hot area such as here in Phoenix my recommendation would be the original R-12. If you’re somewhere that isn’t as hot, a conversion to R-134a may work well enough.
Another option is the Vintage Air kit - presume you've read threads about it but the under-dash AC box is electronic, so no dependency on vacuum or mechanical cable controls. Also eliminates the under-hood evap core assembly from the mix, so the right side of your motor is completely opened up for top-side access.
The Sanden-style compressor is more efficient and takes up less room than the OEM unit. Also, my '72 is a factory AC car and the brackets that mount it are less cumbersome than the OEM pieces, increasing the frontal access to other right-side components.
If you're not maintaining authenticity, it's a great option to contemplate for the money
Not sure what year your car is, I have a 72 Cutlass S with factory A/C. It has an accumulator (or dryer) and manifold line from a mid 80s cutlass with a fixed orafice tube with the factory adjustable pressure cycling switch. This setup allows you to run 134 and you can adjust the cut out pressure on the switch via the adjustment screw. I also added a 16” electric pusher fan on the front of the condenser(that only runs when the a/c is on) to help control the high side pressure and help it stay cooler in traffic. It works just fine with the factory compressor and clutch. This eliminates the expansion valve and POA valve and turns it into a more modern system. Has been working good for me. see pic below.
R-12 isn't astronomically expensive like it was years ago. You should be able to find some. Plus, your AC system isn't going to cool as well with R134A. If you want to run R134A then get an aftermarket system.
I bought Original Air's Series I set up for my 1979 Blue Calais, the Sanden Compressor is a huge improvement over the original factory compressors, less HP drain on my 105 hp motor. I sprung for the extra $75 for the black powder-coated unit so it wouldn't look like I have 2 Alternators under the hood. The entire right side of the engine is now more easily accessible as the brackets are smaller. If you are going R-134 this is a decent alternative.
Last edited by BlueCalais79; Jun 7, 2023 at 05:10 AM.
Here's a summary of the information you need to make the R-12/R-134a decision.
R-12 cools better in our classics, hands down. The reasons are that the R-134a does not condense completely in our OEM condensers (that were, naturally, designed for R-12) and the evaporation pressure of the two is different. Physical changes are required to make the most of the R-134a capacity.
You will need to adjust the POA valve to account for the different pressure range of R-134a (if you want to pursue this, I'll give you more details).
Then purchase "Air Conditioning Clean and Flush" at your local parts store. Run it through everything, let it soak, and blow it out with compressed air. Don't skip the compressor--there's lots of oil in there that needs to be removed.
Change all the O-rings to the green ones.
The old hoses are OK because over decades they develop an interior varnish that keeps R-134a from penetrating.
Last, add R-134a oil and refrigerant.
You will then have a stock-appearing system that will cool as well with R-134a as it did with R-12.
With the foregoing in mind, you can make your R-12/R-134a decision.
And we all would understand if you chose to stay with R-12!
The two most important things when converting from R12 to R134a is to recalibrate the POA valve and to install a parallel flow condenser. 134a boils at a different pressure which is why the POA valve needs to be recalibrated and 134a is less efficient than R12 so the condenser needs more surface area to fully expel the heat. Classic Auto Air sells a bolt-in parallel flow condenser or you can build your own brackets and install a universal fit part: the universal part is much less expensive but you'll have more time invested to get it to fit.
FWIW, I had a 90 Buick Estate Wagon years ago I converted from R12 to R134a. As others said, it takes more than just slapping on fitting adapters and charging the system. My Buick never cooled well with R134a.
I used the Original Air compressor conversion package on my 67 Delta. I was impressed with the design of their bracket, which has a lot of adjustability to accommodate different belt and pulley offsets. I retained the original evaporator and condenser, but converted to a CCOT system using their POA valve replacement kit.
