I converted my system about month ago ro r134a I wish I would know about freeze 12. My car had nothing in thewhen I converted the hose from the comprosser was off and the valve was broken. After I fixed those I just added r134a. IT took one can to get the compresser to run. Actual it still wouldn't run after that so II pulled the battery cable let it sit for 5 minutes. Then put the cable back on the battery and the compressor started to move. Make sure the air is on max when you start adding. the 1st can I added went I really slow (the compressor wasn't running). Then added the second can r134a the temp of the vent was still only 75 when outside temp 87 and the hudmidty was 70%. Then I added I dye tracer to the system so I would know where it was leaking which also had stop leak in it(I think most people on this site will agree that only covers up the problem,but alll the dye tracer had stop leak in them that I could find. Then I added anotheir can of r134a. then the system got down to 58. which for a converted system at that temp I heard is good. The other the might help is to buy a converted system that had gauge to measure what is in the system, I was lucking in my car because usually air instde the line will ruin the the evapotar core. But my system has been running for month no dye coming out or nothing. Still get down to 54-58 depending outside enviorment.
2007 Dodge Caliber v4 5714 miles(cvt) tranny)
2002 Malibu 3100 117000 miles