Auto A/C retrofit from R12 to R134a needs work, what else can I do to make the system function properly?

R134a Retro fit procedures. I have replaced the Expansion Valve, and the Receiver on my R12 system. The A/C blows cooler, but not cold. What do I need to do to make it cooler? I am thinking of taking the Evaporator(underdash board) out again to blow serious air pressure through to clear it out. It may have sludge some articles state. But, I am not convinece that is the only thing. The pressure is not even on the High, and Low side, when charaged. I replaced the components, vaccumed the system, and charged it, and all I get is a 5 degree change. What will it take to make my retrofit work properly? Sorry, for being redundant.

Auto A/C retrofit from R12 to R134a needs work, what else can I do to make the system function properly?
replaced the oriface tube. the orifaces also come in different sizes. the smaller the colder. thats what makes the difference in how cold you want your ac. just like air.... lots of air forced through a small hole and the colder it comes out on the other side.
Reply:You have to pull a vacume down past 0 this takes about an hour sometimes and then if it holds at this for awhile then it is safe to put in the r134a.without opening the system,and check to see how much your a/c system holds before you start and dont over-fill it.most a/c systems dont have as much trouble as you have said you do,i have a 91 camry also and it is a great car.Good luck.
Reply:Did you replace the compressor? Did you flush the mineral oil out of all components and hoses? Did you change the O-rings on the fittings? Did you replace the cycling switch with one set up for R134a? Did you charge it back with the correct amount of R134a and the correct oil? A lot of unanswered questions there for me. A/C work, and especially a retrofit, is not something the normal DIY'er can do succesfully. You best take it to a professional for that job.
Reply:try calling Car talk
Reply:when using low temp refrigerants you must make sure all moisture is removed from the system or it will freeze at the expansion device. using a vacuum pump without a micron guage is no help.your guage reading of -15 means the unit is doing what we call pumping down or restricted but without high -side reading it could be undercharged.
Reply:should have changed o rings and seals also.and used a quality flushing agent available at auto supply.all r12 contamanated parts have to be replaced.as long as evaperator is flushed and not leaking should be usable.good luck
Reply:How did you vacuum the system? What type of vacuum pump and for how long did you vacuum? Also did you use a gauge set that allowed you to read low and high pressure during A/C operation? If so, what were the pressures?