How do I tell if my A/C runs R-12 or R-134a?
 

I just bought an '83 300DT last week and need to add a can of refrigerant/stop leak. I bought a can of R-134a with stop leak but I've read on the internet that my car might take R-12 refrigerant if it hasn't been converted to R-134a? How do I tell which one my car takes? Thanks

And also, the air isn't blowing as well. Does this mean the compressor isn't working or will a can of refrigerant/stop leak fix this? Forgive me, I'm a total beginner with this stuff...

Here we go, that time of year.
If it has been converted it will have fittings for r-134a. You need to look at the "inner" section of the compressor pulley to see if it is turning when the engine is running and the center button is pressed on the climate control unit and the dial is in the coldest position.

I'm a learner myself, but I can tell you the experts say not to use stop leak in your a/c system.

There is a sticky at the top of the page... a good place to start your AC education......
You can easily be in worse shape after using a stop leak than before....
consider finding the cause of the leak... which might just involve tightening a junction using two wrenches... after locating it with soapy water.. . if you can not find it that way you might have a shop just find the leak using an electronic leak detector... needed if the leak is in the evaporator under your dash..... do a little reading and then you will know more about what direction you can and want to take...then tell us and we will try to steer you to cold air as cheaply as possible.....

is there a sticky or somewhere i can find out how to do the soapy water trick? how much do you think it would cost to get a shop to find the leak? i want to learn to do all of this myself but im seriously starting from square 1 so bear with me. ill start educating myself with the AC sticky, thanks

check your pm's....

also start reading at Aircondition.com

You can look for a label stuck to the radiator support. If it was converted properly someone should have stuck the label on there.

You can also look at the fittings on the A/C manifolds. Do a google search for images of 134a connectors.

Paying a shop to do a leak test before you've done some basic inspecting is a quick way to get into an expensive repair. Do a little research on the components, look around for leaking bright green oil on the A/C components (bright green flourescent dye to help ID leaks).

Do a little electrical troubleshooting to learn how to jumper your compressor and the aux fan. That way you can start figuring out if the individual components work before attacking the whole system.

Welcome to the forum!
and feel free to ask Leathermang, or myself any and all a/c questions you might have.