A bit of a tangent, but worth noting.[snip]
One nice thing about the Esprit A/C is that it still included the Sight Glass at the RH front area of the front trunk. If that shows "bubbly" you are not fully charged, and the Esprit system contains a LOT of refrigerant.
My 88 had its R12 system professionally (?) converted to R134 by the PO.
When I bought the car, it was checked out (loose wire found) and pressure/leak tested, and topped off with the 'recommended' R134 level. It worked well in Northern California summers, but after 90 mins of operation in 90F weather, the mechanical relief valve would blow, venting R134 out (to protect the compressor due to high pressure).
There is a long thread I had on this. Bottom line was that the 'recommended' R134 (calculated from the original R12) level was simply too high. After the 3rd relief valve blow, I recharged myself to only 80% of the charge - never had a problem since, and it blows reasonably cold even for a San Jose 90F day. I also changed the drier - it's possible that action also got rid of some contaminant, but for now, I'll stick with this lower charge level (and yes, I do see some bubbling in the window).