I just bought a 1993 Impreza L 2 months ago with a bad A/C. I was going to convert it to R134A but I'm confused by what I found. It still has the R12 sticker but the connector seems to be R134A already.

 

This is a low side R134A connector right?

 

With a high side R12 connector?

 

So it's fairly likely that it was already running R134A but whoever did it didn't put a R134A sticker? Any way to be 100% sure other than taking it in?

 

Also from what I've read the compressor won't run if the gas is low to prevent it from running so assuming that the gas is low, I probably have a leak and not a bad compressor?

 

Bonus shot of the 93 L with my 2000 L (my girlfriend: "couldn't you have at least gotten a different color?":) )

Yes, that looks like an R-134 connector that has been screwed onto an existing R-12 fitting. Looks like previous owner already converted to R-134 refrigerant. My guess is that connector in your picture is actually screwed onto the low pressure side, not the high side. The fitting should have a blue color dust cap cover on the end of it. Blue cover cap denotes low pressure, red denotes high presure.

 

Yes, if the system is low on 134 refrigerant, the A/C compressor will not turn on. If you are handy, add a can or two of 134 to the system. However, be sure that you are adding to the low pressure side, not the high pressure side. Suggest taking the car to a Autozone or Advance Auto parts store. One of their counter guys will verify which port is the low side, and then sell you a 134 kit, or hose and 134 cans to recharge the system yourself. That is a whole lot cheaper then taking the car to a repair shop. If you have a small leak, one can of 134/year may be all that you need to keep your A/C system pumping out cold air. Good luck

Perhaps one day, the previous owner decided to top off the refrigerant and, since only R134A is available for doing it yourself, just screwed on a low-side fitting and proceeded happily to fill it up from a can. If there's no known repair history and you want a working AC, the system should be evacuated, flushed, and charged (after fixing the leaks) with refrigerant and oil. The receiver-drier will have to be replaced.

OTOH, just filling it up with R134A might not make it any worse right now, so you could try that. In that case, use one can that has added dye, and also add some ester oil to keep the compressor from seizing.