[Goldfinger]

Black there is a such thing on our vehicles for running a/c while stopped it's called an idle compensator it raises the idle allowing the engine to run properly. I had low air pressure through my vents. i crawled under the dash to find 25 years had harmed my vents with some duct tape around the seals it remedied the problem. For max cooling i added insulation around my lines to prevent thermal loss. Also my a/c has an adapter to allow use of 134 with the existing oil and r12. also check for leaks.