[KStark]

How well did the factory air conditioning systems really work compared to the performance chart in the shop manual? The 72 Pontiac shop manual shows duct temperatures in the 40-45 degree range, as ambient air temp climbs from 70 to 100 degrees. Low side pressure remains around 30-32. These are under what they called "arid" conditions. My 72 Firebird (after many a summer battling the A/C) has always only been able to achieve around a 35 deg temperature drop, compared to the 50-60 deg drop in the book. A 96 Honda under the same conditions drops the temp around 40 degrees. The Firebird is a stock system (a6/POA/R-12/etc.) Is this permormance acceptable?

[engineer]

looks like you answered it when you mentioned that the 96 honda only did a 40 degree drop vs. a 35 degree drop on a system that is 24 years older. So yes,it is acceptable based on your test. 96 r 134A, orifice tube, compact compressor. But Honda is more efficient.

[KStark]

Thanks, but what about when the Firebird was new (or at least the HVAC)? Were they really significantly better than the current sytems?

[judgethis]

A 35 degree temp drop is pretty good. It probably wasn't any cooler than that when new. New cars probably get cooler because hvac systems are now contained under the dash versus the old cars where the evap was outside the fire wall in the heat of the engine. But even new cars only get about a 40 degree drop. Also look at were the fans are placed in the system now compared to back in the day. Air has to travel less distance in the new cars. Id be happy with a 35 degree drop.

[HWYSTR455]

I don't know, think you may want to look at it, since mine I believe gets the 50-60 drop. There are times on the highway that there's no way you can keep it on high, will freeze you out! Mine's all factory too, (R12, POA, A6), though this year I believe the POA is starting to act up. I remember my dad's Olds 98 in the day would actually spit frost! You could see your breath in that car, and used to in mine, as recent as last year. I think it's possible to get BETTER than what the factory manual specs suggest.

When I had mine charged, I had the guy at the shop leave it in evac forever and suck it down as far as possible before charging. Maybe that made the difference....