I just bought a '91 with 83K and a sticker indicating a R134a conversion was completed. While conducting a PPI with the car sitting inside a service bay (i.e. in the shade in a conditioned space) I measured the temperature drop with an IR thermometer with the A/C running to be 30 degrees less than ambient at the center vents. I was told the HVAC unit had the electronics repaired, and it didn't seem to malfunction in any way. However, upon driving the car home in record MN heat (91F on Tuesday!), with the engine adding to the cabin heat load, as well as the solar gain of the black roof, the HVAC couldn't keep up at all. I was sweating and dehydrated while driving. My Honda engineer friend said R-12 is a better refrigerant, so the NSX system designed around R-12 may just be undersized running R134a. What say you? Is this normal performance or is my system ailing?