Looking for advice on A/C

I used a stock '64 Dart setup, with the exception of the filter-dryer (it has to be new, and the horizontal style was not available, so I used a vertical style unit). Compressor and brackets and under-dash unit were all '64 Dart items. The upper bracket for the '64 Dart underdash unit brings the unit right up against the bottom of the dashboard, which works fine in a '64, but in a '62 it prevents the glovebox being opened more than a couple of inches. The '62 upper mount bracket had about 2 inches of offset to it so the front of the unit was lower, thus allowing the glovebox to open all the way. It wouldn't be too hard to fabricate an offset top bracket from sheetmetal, but I never got around to it; I'm almost never in the glovebox anyhow. I did have to move the fusebox, which was not difficult.

There are aftermarket compressor mount/drive kits for the slant-6. These are poorly designed and problematic even on later cars with a relatively large amount of room under the hood -- much more problematic in our '62s with their cramped engine compartments. It is commonly but mistakenly believed that the later-type compressors take less power to turn than the old type. That's not correct. The later compressors (no mount for them exists for a car like ours, though one could probably be fabricated if you don't have power steering) weigh less than the old ones, and their input torque requirement is smoother/less peaky, but that's all. The original type compressor is heavy and its torque input requirement is peaky, but it's also extremely durable and reliable, not least because it has its own built-in oil pump.

I upgraded the radiator (see here and here and the radiator fan (see here, because that's very necessary, and had the windows tinted with an eye towards heat blocking, not so much towards darkening the glass (Llumar Air 80, almost invisible and cuts heat entry a LOT), because otherwise you're fighting a losing battle to keep a solar oven cool.

If you're wanting factory Chrysler-made parts, the '61-'63 under-dash units are almost impossible to find in any condition, let alone good condition. The '64-'68 type (like I have in my '62) is somewhat less difficult but still not at all common (I have a perfect new-old-stock '64 unit on my shelf; send me a PM if you're after it). The compressor won't be difficult. The correct compressor bracket won't be easy but won't be impossible. Condenser should be a new parallel-flow type, as large as you can fit, to maximize performance and minimize drag on the engine (don't believe me? See for yourself).

There are two and only two refrigerants you should consider using. R134a should be the first choice. It is readily and inexpensively available and any A/C service shop will work with an R134a system. All you have to do, aside from the parallel-flow condenser, is make sure the compressor has a new shaft seal in it, the new hoses are barrier type and the gaskets are R134a compatible (standard practice for 20+ years now) and the compressor is filled to the appropriate level with R134a-compatible oil.

R12 is the original pre-1994 refrigerant. It works well, and is compatible with lower-grade compressor shaft seals and older hose and gasket materials and compressor oils, but is a hassle to get hold of and many shops either won't work with it any longer or charge extra.

Do not(!) use any other refrigerant besides R134a or R12. There are hydrocarbon offerings ("HC-12a", "Redtek", "OZ-12", "Envirosafe", etc), these are isopropane/isobutane blends. They work, in that they are compatible with the old R12 materials and oils and they cool effectively. They're cheap. They are also illegal (except for loopholes) and hideously dangerous. Yes, you carry around a tank of gasoline with you...and even in 1962, that and the rest of the fuel system were specifically designed to carry and transport flammable liquid and vapor. The A/C system was not. Most shops will either order you to take your car and leave or will charge very hefty fines to get the torch fuel out of your system. It is utterly false economy and way beyond stupid to "misfuel" an A/C system in this manner. Just don't.

The other big upgrades have nothing to do with the workings of the A/C system itself: insulate the car! Find and seal all the holes in the firewall and floor pan (there are many), take down the headliner and put insulation up there before reinstalling the headliner, insulate the door panels. This will dramatically reduce the "solar oven" effect that defeats even the best-working A/C system.