a few years ago I put a vintage air under dash unit in (different skylark) Even though the ac blew very cold the car never cooled off. I insulated the roof, that helped a lot the floor was insulted also. Anyone have cold ac on hot days? Cheers!
There are a lot of air leaks in these older cars, they may be small leaks, but they all add up. Window seals, door seals, body plugs, trunk to passenger compartment, firewall, floor, etc. In my wifes Tahoe with the AC on, I can tell when she has her window cracked just a half inch, it makes a BIG difference.
When i put the factory ac back on my black 67 i had 37 degrees out of the vents. But just like u it did not seem to overall cool as good as newer vehicles. I put mild tint on the windows. 35 pct. It made a considerable difference. The windows before acted like magnifying glasses on my arm from the sunlight and now that does not happen. For the record they are original softray windows in the car.
My white Skylark has nice cold AC. 39-40 degrees out of the vents using a pro-6ten compressor on R12. All the door/window seals are in very nice shape which I think is the key on these older cars. It cools plenty enough to be comfortable on an 85-90 degree day.
Also the doors themselves, they are sealed much tighter today than just a plastic vapor barrier like older cars.
My vents seem to blow pretty well, and regulate properly. I'm concerned about it not cooling well enough too, but I'm about to throw a ton of money at it anyway.
That is the only upside to electric fans in my opinion, moving enough air at idle across the condenser to keep the AC blowing cold. A painted steel roof will get a lot hotter than one with a vinyl top, I'd leave it on.
