I converted my 87' 300E to 134A two years ago. I live in Vancouver B.C. and it became illegal to charge with R12. The climate control works great except when the temp. is above 28C and stuck in traffic. I have made some inquiries here and suspect the condensor isn't efficient enough. Every spring I perform an evacuation and re-charge on the system and have not noticed a significant loss of refrigerant.
'87 300E 338,000 km