I converted my 1983 W123 to an R134 system. It was done as recommended by changing all components except the condenser. I now wish I hadn't done so. It has been about 5 years. The system cools fine while underway but just does not put out well at idle as you describe. I live about 25 miles from the closest town and if I park at work on a hot day even with my windshield covered the interior just starts to feel cool by the time I get home.

I am told that a good parallel flow condenser would cure my ills. I have been looking (not very hard) for one since. If I can find one at a reasonable cost I may install. I will also talk with my local ac expert irt R152 based on your experience.

Thanks for that. This is what this forum is for.