Originally Posted By: Hokiefyd
Both of our 134 systems blow air colder than we can stand it, both have well over 100,000 miles, and neither have been opened up. The MDX even has a separate system for the rear area, so it's got a huge cabin to cool. I've also put auxiliary PS and ATF coolers in front of the condenser (the Ridgeline has them, too, but they're factory installed).
I think 134 conversions were sketchy, but a properly-designed system should work very well.
The key is properly designed systems.
R12 systems were optimized for the working thermodynamics of that fluid, which was different, and when the 134a was put in, in addition to having different pressure-temperature behaviors, it also was only filled like 75 or 80% (IIRC) as much as R134a. That makes a big difference on a hot day!
Some systems worked well. Others can be made to work well, especially if a parallel flow condensor, and a full flush and refill with the right oil, etc is done. I didnt do the parallel flow condensor on my 91 318i, but it worked really well until you got to the 95+ days in traffic on the asphalt.
My w123 Mercedes just dont have enough condensor area to do the job stock, plus they only have an R4 compressor. Put in a parallel flow condenser, a Sanden compressor, and some new barrier lines, and they can work OK... But by the time you go through all that, why not just make the system tight and run R-12, especially since it has come down in price. When I run out of R12, Ill do propane/isobutane.
Originally Posted By: Jarlaxle
Or just do an R-134a conversion correctly, and have div>
As mentioned above, its not necessarily just about temperature... You need mass flow across the evaporator, and R134 has less mass to begin with, before you even start on the basis of P-T behavior.
