R12 or R134 how to tell
 

hello

how can i tell what type refrigerant system is in my cars. last time i concerned myself was in the late 60's and early 70's. didn't need to know cause it was all r12 i'm sure.

Cars converted to R134A usually have a sticker under the hood somewhere stating so. Also, the Schrader (spelling?) valve on R134A cars tends to be blue, but on R12 cars it tends to be black. Your's may vary!

If they've been properly converted there will be different fittings on the access ports. They look a little like quick connect fittings found on shop air tools.

That said, this is still no conclusive evidence. There are so many people putting so much junk in a/c systems these days that the only way to know for sure is to go to an automotive a/c shop and have them connect their refrigerant identifier instrument.

By law a conversion is supposed to have the correct fittings and a conversion sticker under the hood. There are, however, many, MANY people illegally converting and putting about every gas known to mankind into these systems.

Good luck,

You can make a rough guess as to whether its R-12 or R 134a based on a temperature/pressure chart. If your pressure matches what R-134a should be at a given ambient temperature, that's probably what you have. The problems are 1. If your system can't hold refrigerant, obviously there won't be any pressure to check. 2. If your system has been cross contaminated (that is, has both R-12 and R-134a in it) your pressures will be higher than either one alone, and 3. As Larry said, some folk put in alternate refrigerant blends that are tough to get information on. Still, most people have R-134a or R-12, so this may help. A chart you can use is available here.

Good luck.

Larry
 

I expected you to say that R12 cools and R134a does not....especially in Indiana summers.