Ice Cold?

R12 is a rarity nowadays, and those who retain the system install the readily available R134.  I have installed this refrigerant in numerous cars, my own included, with marginal results.  Interesting that ads I see for similar cars always say ice cold A/C.  What the hell is wrong?  But then again it’s craigslist, it’s all lies.  I’ve even tried varying amounts refrigerant, using the high tech shop equipment, but never can obtain the results I require.  The usual rule of thumb is about –30 deg from ambient temp.  I usually end with approximately –10 deg.   Not bad but not great.  One solution is to change to a larger condenser and/or change out the expansion valve suitable for R134.  But I like stock, so the only other option is to look for a more suitable refrigerant that will work with the current system.  So that’s will be the hunt for this summer.  Hopefully summer won’t be over before I find a solution.