Probably replacing the drier and flushing the system wouldn't hurt things, but if it's working I wouldn't open it up to do either. I'm no AC expert, but I believe that usually the AC is spec'd to cool down to a delta of around 20 degrees, so if it's 71 deg or greater, then 51 at your vents sounds good. Maybe you can clean the fins on the condenser to make sure you get good air flow (prob doesn't matter sitting still at idle though). Once you open the sytem and flush it and replace the drier, then you have to evacuate it with a vacuum pump for several hours to remove moisture. Seems like a lot of work that may not improve things much. I've also heard that early R-134 systems just didn't cool very well compared to R-12.

It worked for my sisters '95 Runner. About 3 yrs ago she was having a hell of time getting it to cool down on hot days, it was only slightly cooler with the A/C on on a 100+ day then with the windows down, but definately not comfy, where as the summer before it had no problems. On visual inspection everything looked good and clean, and everything sounded good as well, the system pressure was also good. The shop recommended before replacing anythin(thus having to open the system), try replacing the old R134 with new(I am not sure if they recommended this just to get more mnoney, or actually new it worked). It seemed a little bogus to me since the A/C system is a closed system and nothing gets in, however changing it out seemed to do the trick. It might be worth a try before replacing expensive pieces. An A/C shop should be able to do all of the work for you, you definately want the to reclaim the R134, it is toxic in both long/short term exposure.

well i'm investing in my own Manifold gauges. so I can see pressure on the lo and hi side. Yeah.. i'm not to fond of opening up a system that is working fine. My guess is I'll buy the manifold gauges this week, play with that for a few days... figure out it's a tad low.. and add a little 134 and call it a day.

do Evaporators get nasty over time? debating seeing if I can gain access to it and clean the fins out on it.

How's the airflow through the vents? A clogged evaporator will reduce the airflow. However, you will probably have to evacuate the a/c, disconnect the lines and pull it out to clean it.

air flow is pretty good.