It's that time of year, AC ? on late W124

[wolf_walker]

I bought this pretty decent 94 E320 this past winter, I think it'd been sitting for a year or so when the PO got too old to drive. AC has worked, but not super well. I noticed on a genuinely warm (high 80'sF) day last week the AC was useless in town, and about ten minutes on the interstate had it working "ok".
I didn't have a thermometer with me, and it's my Very Significant Others daily, she's used to crappy AC the poor thing and didn't mention it.

Anyway, the PO had the compressor and some other stuff replaced not too long ago at an inde shop, I have the receipt somewhere. I verified the electric fans were not coming on with the AC, verified they did in fact work, took a wild guess and put a little R134 in it from one of those generic cans from the McParts store I had laying around, and the fans started to cycle.
For what little it's worth, it was in the low to mid 70's by then and by the little gauge on the bottle on the low side I finally got it up to where it was cycling between 26/36psi, fans were cycling, but it never managed a center vent temp on full cold, recirc, high blower, of lower than 62. I intend to try a 2nd thermostat as I swear it felt colder than that but I know "feel" isn't a good way to judge things.

So, the system seems to work, wasn't so low after a year or two that it wouldn't function on the highway, has a newish compressor(which I assume is from autozone or such), the compressor never cycles, the climate control seem to function correctly(after having the AC on a while and turning it off I don't detect any warmer than ambient air as if a blend door was leaking or such), it has had at least one of the dash pods serviced in the past and also the evaporator earlier in life by a dealer, the condenser is clean. My thought it to evacuate the system, vacuum it a while, and recharge it with the stated 2.2lbs or whatever it is and see what that gets me. My Father has a vacuum pump and manifold gauges and has a lot of experience with older R12 systems and will assist. Thoughts?