The real bottleneck in the ac system is the small evaporator they put in these cars. That said, I agree that among the things you have control over, getting air across the evaporator is most critical. that is why when i rebuilt mine (converted to 134) I re-wired the aux fan to go on with the compressor does...I do realize that there are times when I am tooling down the highway going 80 when the aux fan comes on with the compressor, and does essentially nothing. that is a trade off I am willing to make.

I did make a few other modifications to the system.....I put in a generic "parrallel flow condensor" to even further enhance the condensing function...to get low side pressures as low as possible. The system works well....center vent temps of 37-38 deg when outdoor temp. is 95 to a hundred (dry humidity). When its very humid though, center vent temps go up.

I dont quite understand why R12 is so much better than R134....after my conversion to R134, the system worked fine. The system cuts out when the thermal switch near at the expansion valve cuts out....this tells me that refrigerant temperatures are getting to the requisite temperature (somewhere just above freezing). the system would cut out at this temp. whether you have R12 or R134. What I find the main problem is, as I said earlier, the small size of the evaporator......it is just not big enough to cool and remove moisture from large volumes of humid air.

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)