"The most important thing about putting air conditioning in a car is preparation," Chisenhall explains. "You've got to have room to install all the components, the car should run cool, and a good fan is vital. In fact, you should try to accommodate the biggest fan you can fit between the engine and the radiator, because that can affect the entire system. In the initial planning stages of your project, leave yourself plenty of room for cooling options."
Moving motor mounts and changing the engine setback is a lot easier in a custom-built street rod than it is in a factory application, but most Detroit iron has plenty of room up front for a large-diameter fan anyway. Chisenhall is running an 18-inch clutch fan on his small-block-Chevy-powered '39 Ford and a 19-inch clutch fan on his F-100 pickup. The climate control guru also warns against using a factory radiator from a car that didn't originally come with A/C, as it probably won't be up to the task of keeping things cool once you throw slap a big condenser in front. There are several aftermarket radiator companies offering a wide range of products more aptly suited to an A/C application, and whether you choose copper/brass or aluminum, either will do an adequate job with sufficient airflow.
"The way to remove heat from refrigerant or coolant is either to increase the face area of the heat exchanger (radiator or condenser) or to move more air through it," Chisenhall says. "Since the face area is fixed by the grille shell size in most hot rods, your only other alternative is to move more air. That's why planning for a big fan beforehand is vital."
Cool-hand Jack goes on to explain that when Vintage Air was faced with changing environmental legislation, forcing a switch from the standard R12 refrigerant to the more environmentally friendly R134a, he saw an opportunity to improve the efficiency of the entire system. "When R134a first came out, people didn't think it worked very well, but that's only because they were putting it in systems designed for R12, which works about as well as running alcohol in a motor set up for gasoline. R134 carries more heat than R12, so you have to get rid of more heat too. The combination of a bigger condenser and R134 works great, but you can't get a standard tube and fin condenser efficient enough to handle an R134 system to fit into the grille of a pre-WWII hot rod. That's why we made the switch to the newer serpentine-style condenser, which flows the refrigerant through oval tubes rather than round tubes, providing more surface area for the refrigerant to touch and thereby increasing heat transfer. Unfortunately, the oval tubes had these small passages, which individually were restrictive to the refrigerant flow when you tried to circulate it through one tube at a time, so the pressure of the system would skyrocket. The solution was to put tanks on both ends of the condenser like a radiator, rather than having the refrigerant snake back and forth through a series of S-curves. Thus the Superflow condenser was born. An added benefit to all this is that when condenser capacity increases, more heat is dissipated, pressure drops, and the compressor becomes easier to turn. This, in turn, means that your engine doesn't have to work so hard, and you get a boost in usable horsepower."
ConclusionUnlike the big, heavy A/C systems of the '50s and '60s, today's climate control setups have benefited from advances in condenser and compressor technology that make installation a breeze. A little forethought and planning will allow you to cruise in comfort with a minimal sacrifice in weight, engine operating temperature, or parasitic power loss. Whether you order an A/C system from an aftermarket vendor or piece together your own, a thorough understanding of the technology at hand as well as an effort to properly prepare your car beforehand will pay off in spades. Now, what are you standing there sweating for? Get to work!