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Help converting factory A/C to R134


FBBO Gold Member
FBBO Gold Member
Local time
10:25 AM
Mar 29, 2021
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Transylvania, EU
I searched the forum (heck, the whole internet) for a guide on how to convert the factory R12 A/C to R134a, but only got the general bit.

I had a wonderfuly working R12 setup (I think I got the last R12 canister in Europe), but after I changed the radiator, the person who did it turned the A/C on, till sparks came flying out of the RV2. I guess air got in the system during the swap, and turning on the compressor sealed its fate.

I did the easy part: new compressor, and drier, and got an electric thermo-switch to replace the mechanical one. Trouble is that I am totaly lost on how to set it up - do I stick the probe thingy in the same location as the stock probe? Do I then tape it so that it stays? And where do I make the electrical connections? Any recommendations on a good match for our cars, and where to find one if mine is not good?

I can't even do a flush right now because every A/C guy I came across here has different filler ports for the gas, I need some sort of adapters. Is it a US vs EU thing, or a R12 vs R134 thing? Could somebody please provide a link to adapters that 100% work for my Charger?

Any issues with oil? I was told that the compressor was pre-filled with compatible oil when I bought it, but how do I check/fill without taking the whole thing apart?

Any guidance would be much welcome.
Also buy a parellel flow condensor
Flush the sysfem
Change ALL the rings to green nitrile
The service manual has the way to measure the oil
There is a pipe bolt on the left side of the clutch remove it and check it with the dipstick that the manual tells you to make see attached, I used an old oil dipstick
Vacuum it for an hour after complete install and before adding freon
Charge three cans of 12 oz 134a putting them In a hot water bath
Charge with 4th can till water runs out of condensation hole and the temp stops going down. Mine took 42 ozs of 134a.

Adapters Aupoko R12 R22 to R134A Conversion Adapter Kit, R12 to R134A Retrofit Valve Fitting Kit for A/C Pro Refrigerant - 2 Kits https://a.co/d/7e7xlq3

SmartSelect_20230522_165125_Adobe Acrobat.jpg
Thank you so much for the help, and the link. Hopefully it will arrive in Europe next week, and I will let everybody know how it goes.
When I converted my '84 Dodge pickup to 134 I took the easy way out and simply used the fittings and necessary small parts that could be easily sourced. It worked, but not great. Later I replaced everything from the firewall out, including the compressor and condenser, with 134 intended components. Now it works great!!
Replacing factory stuff with something from the aftermarket sure does simplify things, but for me it's important to keep everything as it came out on May 19th 1968.

Can anybody tell me how do I proceed with the electric thermostat switch? This is what I got: Google Image Result for https://m.media-amazon.com/images/I/71EeklvChbL._AC_UF894,1000_QL80_.jpg

UAC SW 6490C, it was recommended from the place I got my new rv2 compressor. I have 3 questions:

1. Do I disconnect the mechanical expansion valve that also has a long capped off hollow tube, because I am installing this electric thingy that also has the long capped off hollow tube? Or do I leave said expansion valve alone?

2. Where do I stick the long capped off hollow tube of the electric thermostat switch? Pics would be a godsend.

3. How do I wire this? Do I just cut the wire to the compressor clutch, and put each end to the two bases?
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