A/C notes

[padgett]

Finally got a digital thermometer out ($10 in kitchen supplies) and measured some real and subjective values on a couple of cars.<P>95 degree bright sunny day, 100 degree pavement temp, high (70%) humidity, coolant in 185-195 range. A/C set to max cool/auto/bilevel. Car retro'd to R-134A.<P>700 rpm Idle at stoplight: 62-64 degrees at outlet. Subjective: cooling but not enough. Note Suspect this is related to air flow, raising rpm further had little effect. Both fans on (HI). Noticed outlet temp would climb to 64-65 if engine fan was on LO.<P>1200 rpm 25-35 mph: 57-58 degrees at outlet. Comfortable.<P>1900 rpm 60-65 mph on freeway: 52-53 degrees at outlet. Definately cold air.<P>This correlates well with the R-12 charts in the 88 service manual. Note: in each case it took a couple of minutes for the temperature to stabilise.<P>Saw similar numbers in TranSport (single compressor, dual air) though was slower to pull down (much larger volume ?)<P>Note: hot soak in sun on T/S brought interior temp to 115F. Initial outlet temp at 84F, after five minutes 64F at 45 mph, slowly pulled down to same numbers as Reatta.