Is my A/C overcharged or undercharged?

Hello,

car: 93 Mazda MPV

I was seeing lots of bubbles in the sight glass last year, so I added a 12 oz can of R-12. I still saw more bubbles so, I added another can. It worked along just fine.

Recently I've noticed short cycling compressor on ocassion as well as cut outs when its warm outside. A/C blows ice cold air, but in warm/hot weather, it would cut out suddenly and will not come back on for a while.

Did I overcharge the system or did it lose charge over one year and became undercharged?

i'm no big expert on ac's, but i don't think that you can really overcharge those systems very easy...
chances are that you lost the charge from a faulty system.....
then again, in '93 they may have started to use r134a (i don't think they did though). Make sure you didn't put r12 in a r134a system by accident (if it's possible... but hey it happens).

if it has a slight glass chances are its a R12 system

the slight glass should not be used as a level inducatior. chances are you are overcharged. take it to techniction with a EPA 609 certifition for the proper charge.

Chances are you put the right stuff in if the fittings fit--they use different fittings so people don't mix them. You can buy a cheap pressure gage-- looks like a tire pressure one-- that will tell you the pressure. If you had a leak that required more charge, chances are that you still have that leak...