It's been a hot summer in Minnesota, routinely in the 90's with high humidity. I find myself driving our '85 Brat more because the AC is better than that in my Lexus. I recognize that the cabin is much smaller and therefore easier to cool but the Brat has over 100K on it and never has had the AC worked on. I'm thinking it might be because the refrigerant is the older R -14.  Of course performance is way down with the AC on, I can tell when the compressor cycles on/off.

Some of the old R-12 systems are pretty good.  Just a guess, maybe less worried about MPG back then, so rhe A/C might be sized more for cooling than efficiency. 

A/C is a few HP load, so it is noticable on a small engine. 

+1 Both compressors have roughly the same internal volume for moving freon, but the Lexus has a variable displacement compressor where the old school Brat compressor is a fixed displacement compressor so it's pumping full tilt all the time (unless the pressure switch shuts it off). The variable displacement may be mechanical or ECU controlled and is based off system pressures, flow and temp to yield acceptable cooling with minimal load on the engine to keep your MPGs up. Add to that, as you stated, the cabin size difference (Lexus being 2-3x the volume of a Brat) and the fact that R134 does not coll as well as R12 and there you have it. Your Lexus may also be having issues. Low charge, sticky temp door, plugged or stuck orifice/TXV or a cooling fan or condensor air flow issue. Give me old school AC any day.

Edited July 15, 20187 yr by skishop69

My 86 GL has a much more robust AC than my Ford Escape. The Escape's AC is wimpy even at optimal status. 

Also the cabin window angles. Brat front window is far less tilted than your Lexus, and your back is vertical. So less heat getting in to begin with, and the AC doesn't need to run as hard to maintain the termperature.

i still get R-12 from Mexico whenever i go visit family overthere to have extra in my garage, something about it makes an old compressor cool like it's on steroids, i heard ammonia cools better than R-12 and i could easily aquire that overthere, but im not risking a leak and dying over that stuff, anyways im sticking with R-12.

my 2004 Oddysey that has R134a takes so long to cool to increase it's terrible 22mpg highway and like 13mpg city, stupid tree huggers.