R12 or 134A? How do I tell what I have?

[Dood1]

1980 C3, AC not working since I got the car, if I press the Schrader valve there is pressure, not sure how much or what's in there. How can I tell if the system may have been converted, how much pressure should I have, and how do I read the pressure? The valve looks like a tire valve but it's bigger, so none of my gauges will work.

 

[Tom73]

R12 and 134a use different types of shrader valves, so if it has been converted it should have a new valve on top of the original shraders. Also there should be a sticker staying it has been converted (Fed Law). But the only real way to find out is to take it to an A/C shop, they have the equipment to analize what is there and tell you what you have.

tom...

 

[Dood1]

Thanks for the info. I just hate to take my car to others, but I guess I'll have to for this one. There isn't a cheap pressure gauge that I can slap on there, like a tire gauge only bigger?

 

[Tom73]

Nope, A/C work takes special guages.

tom...